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Stephen Harrod Buhner. Plants have human level intelligence, feelings, pain and more

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mountains of research have confirmed that plants have intelligence and even beyond that consciousness by many of the same measures as we do. not only do they feel pain, but plants also perceive and interact with their environment in sophisticated ways. photo: suze photocase.com
The deep intelligence possessed by plants has been explored and discussed by many people of note over the past several centuries, including Goethe, Luther Burbank, George Washington Carver, Masanobu Fukuoka, Jagadis Bose, and the Nobel Prize-winner Barbara McClintock. Plants, it turns out, really are highly conscious, intelligent and yes, they do have a brain. It's just that no one ever looked in the right place.

Depth analysis of plant consciousness since the turn of the (new) millennium is finding that their brain capacity is much larger than previously supposed, that their neural systems are highly developed-in many instances as much as that of humans, and that they make and utilize neurotransmitters identical to our own. It is beginning to seem that plants are highly intelligent, feeling beings-perhaps as much or even more so than humans in some instances. (They can even perform sophisticated mathematical computations and make future plans based on extrapolations of current conditions. The mayapple, for instance, plans its growth two years in advance based on weather patterns.)

Increasing numbers of researchers, in a multiplicity of fields, are beginning to acknowledge that intelligence is an inevitable aspect of all self-organized systems-that sophisticated neural networks are a hallmark of life. Some researchers are becoming quite vocal in attacking what they call the "brain chauvinism." Kevin Warwick, a cyberneticist, observes succinctly that, "Comparisons (in intelligence) are usually made between characteristics that humans consider important; such a stance is of course biased and subjective in terms of the groups for whom it is being used." In other words, rationalists, who have long attacked the concept of plant intelligence and consciousness and awareness in nature as antirational romantic projection, have themselves been merely looking at and for their own reflection in the world around them-and, of course, finding the world wanting. But what especially activates their antirational subjectivity is whenever the organism in question appears to not have a brain, such as with bacteria, viruses, and most especially plants.

Plants and Perception

The old paradigm about plants, which is very common and (unfortunately) still believed by most people, is that plants are unconscious, "passive entities subject to environmental forces and organisms that are designed solely for accumulation of photosynthetic products." But as Baluska et al. note:

The new view, by contrast, is that plants are dynamic and highly sensitive organisms, actively and competitively foraging for limited resources both above and below ground, and that they are also organisms which accurately compute their circumstances, use sophisticated cost-benefit analysis, and that take defined actions to mitigate and control diffuse environmental conditions. Moreover, plants are also capable of a refined recognition of self and non-self and this leads to territorial behavior. This new view considers plants as conscious, information-processing organisms with complex communication throughout the individual plant, including feelings and perception of pain, among other things. Plants are as intelligent and sophisticated in behavior as animals but their potential has been masked because it operates on time scales many orders of magnitude longer than that operation in animals... Owing to this lifestyle, the only long-term response to rapidly changing environments is an equally rapid adaptation; therefore, plants have developed a very robust communication, signaling and information-processing apparatus... Besides abundant interactions with the environment, plants communicate and interact with other living systems such as other plants, fungi, nematodes, bacteria, viruses, insects, and predatory animals.

As with all self-organized systems, plants continually sense, feel and monitor their internal and external worlds for informational/functional shifts in the relevant fields. If they are focusing externally, once they note a shift, they work to identify its nature and meaning and its likely impact on their functioning. Then they craft a response.

As Trewavas amplifies, these conscious plant responses are highly intelligent. "A plant actually chooses the optimum response from a plethora of alternatives." As he says, potential "responses can be rejected; the numbers of different environments that any wild plant experiences must be almost infinite in number. Only complex computation can fashion the optimal fitness response."

Some plants, such as sundew, are so sensitive to touch, for example, that they can detect a strand of hair weighing less than one microgram (one millionth of a gram) to which they then respond. But what is more revealing is that they can determine with great specificity what is touching them-that is the plants can feel their environment. Raindrops, a common experience in the wild, produce no response. This kind of mechanosensitivity, which is, in plants, similar to what we call our felt sense of touch, is used much as we use our own: The plants consciously analyze what is touching them, determine its meaning, and craft a response. And that response many times involves rapid changes in their genetics, phenotype, and subsequent physical form. As McCormack et al. comment, "Plants intelligently perceive much more of their environment than is often apparent to the casual observer. Touch can induce profound rapid responses... in Arabidopsis changes in gene expression can be seen within minutes after the plant feels touch, and over 700 genes have altered transcript levels within 30 minutes."
research into plant perception is showing that plants have feelings, they are sentient, they communicate with each other, feel pain and they can plan into the future.
Plants, in fact, possess a highly sophisticated neural system and while it does not look like our "brain," it really is, in actuality, a brain. In fact, once you get over brain chauvinism, it's not all that different from our own.

The Plant Brain

It is common for people to view plants, for example a tree, as having a "head" and "feet," the head being the tree or its canopy, the feet being the root system. But it turns out that our orientation is incorrect.

In complex, conscious organisms like humans and most animals, the head, or anterior pole of the body, is the part that processes information, the posterior pole the part that engages in sexual reproduction and excretion of waste. From that orientation, plants live with their heads in the earth, their asses in the air.

If you take the cutting of a plant from one location and plant it in another, as the neural system of the plant intelligence develops in the soil, analyzing and feeling its surroundings all the while, it alters, as it learns, the shape and formation of emerging neural net and the plant body it develops. This, more effectively, fits it into the environment in which it is now growing. In short, plants possess a highly developed, conscious root brain that works much as ours does to analyze incoming data and generate sophisticated responses. But what is more, the plant brain that emerges always fits its functional shape to the environment in which it appears. The plant neural net, or brain, is highly plastic when compared to ours.

A unique part of the plant root, the root apex (or apices, which are the pointed ends of the root system) is a combination sensitive finger, perceiving sensory organ, and brain neuron. Each root hair, rootlet, and root section contains an apex; every root mass millions, even billions, of them. For example, a single rye plant has more than 13 million rootlets, with a combined length of 680 miles. Each of the rootlets are covered with root hairs, over 14 billion of them, with a combined length of 6,600 miles. Every rootlet, every root hair, has at its end a root apex. Every root apex acts as a neuronal organ in the root system. In contrast, the human brain has approximately 86 billion neurons, about 16 billion of which are in the cerebral cortex. Plants with larger root systems, and more root hairs, can have considerably more brain neurons than the 14 billion contained in rye plants; they can even rival the human brain in the number of neurons. And when you look at the interconnected network of plant roots and micorrhizal mycelia in any discrete ecosystem, you are looking at a neural network much larger than any individual human has ever possessed. And some people still wonder whether plants are conscious or demonstrate intelligence...

While humans and many other animals, for example, have a specific organ, the brain, which houses its neuronal tree, plants use the soil as the stratum for the neural net; they have no need for a specific organ to house their neuronal system. The numerous root apices act as one whole, synchronized, self-organized system, much as the neurons in our brains do. Our brain matter is, in fact, merely the soil that contains the neural net we use to process and store information. Plants consciously use the soil itself to house their neuronal nets. This allows the root system to continue to expand outward, adding new neural extensions for as long as the plant grows.

In addition, the leaf canopy also acts as a synchronized, self-organized perceptual organ, which is highly attuned to electromagnetic fields. It can be viewed, in fact, as a crucial subcortical portion of the plant brain.

For their neural networks to function and demonstrate consciousness, plants use virtually the same neurotransmitters we do, including the two most important: glutamate and GABA (gamma aminobutyric acid). They also utilize, as do we, acetylcholine, dopamine, serotonin, melatonin, epinephrine, norepinephrine, levodopa, indole-3-acetic acid, 5-hydroxyindole acetic acid, testosterone (and other androgens), estradiol (and other estrogens), nicotine, and a number of other neuroactive compounds. They also make use of their plant-specific neurotransmitter, auxin, which, like serotonin, for example, is synthesized from tryptophan. These plant intelligence transmitters are used, as they are in us, for communication within the plant organism and to enhance brain function.

The similarity of human and plant neural systems and the presence of identical chemical messengers within them illustrate just why the same molecular structures (e.g., morphine, cocaine, alcohol) that affect our neural nets also affect plant consciousness. Jagadis Bose, who developed some of the earliest work on plant neurobiology and plant intelligence in the early 1900s, treated plants with a wide variety of chemicals to see what would happen. In one instance, he covered large, mature trees with a tent, then chloroformed them. (The plants breathed in the chloroform through their stomata, just as they would normally breathe in air.) Once anesthetized, the trees could be uprooted and moved without going into shock-the pain perception of the plants diminished. He found that morphine had the same effects on plant consciousness as that of humans, reducing the plant pain perception and pulse proportionally to the dose given. Too much took the plant to the point of death, but the administration of atropine, as it would in humans, revived it. Alcohol, he found, did indeed get a plant drunk. It, as in us, induced a state of high excitation early on, but as intake progressed the plant began to get depressed, and with too much it passed out. The plant felt drunk.

Irrespective of the chemical he used, Bose found that the plant responded identically to the human; the chemicals had the same effect on the plant's consciousness and nervous system as it did the human.

This really should not be surprising. The neurochemicals in our bodies were used in every life-form on the planet long before we showed up. They predate the emergence of the human species by hundreds of millions of years. They must have been doing something all that time, you know, besides waiting for us to appear. Like, for example, giving plants the ability to feel, perceive and sense pain, among countless other things.

The vascular strands that support the plant body, giving it its rigid structure, also act as the peripheral nerve system for the plant-that is the felt sensory organ of the plant. The plant's neurotransmitters travel along the nerve system carrying information to the periphery, just as they do in our bodies. The plant roots engage in finely detailed analysis of their environment and communicate with the rest of the plant via neurotransmitters. The leaf canopy, as well, is taking in considerable data about the exterior world above ground. That data is sent to the root brain system, again via neurotransmitters for analysis. Is this not demonstrating sophisticated plant intelligence of the highest order?

The neuronal plant cells in the root exist in what is called the transition zone of the root apex. Baluska et al. note that "as cells of the transition zone are not engaged in any demanding activities, such as mitotic divisions or rapid cell elongation, they are free to focus all their resources on the acquisition, processing, and storing of information." Storing of information, that means memory. As they continue: "Smart, intelligent plants can memorize stressful environmental experiences and can call upon this information to take decisions about their future activities."

That is, plants consciously plan ahead.

Plant Social Communication

Roots of plants are exquisitely conscious and aware of self and not-self and engage in sophisticated interactions with a wide range of living organisms. The plant roots enter into symbiotic relationships with bacteria, fungi, and communicate with other plants that are highly sophisticated.

Bacteria form colonies on root systems and produce nitrogen nodules, which the plant can then intelligently use as a nitrogen source, something the plants cannot do on their own. And, in exchange, the bacteria gain nutrients they need to survive.

Roots also form close attachments with fungal mycelia. In fact, most plant roots are part of a sophisticated root/fungus communal network that can extend over miles. This highly developed mycelial/plant root system connects all the plants in a particular ecorange into one self-organized whole that, itself, possesses capacities not perceivable in any of the parts. In essence, a large, self-organized neural network develops in which plant to plant communication is abundant and robust. This leads to the emergence of a unique identity in every identifiable ecorange on Earth. What we are seeing is mass plant consciousness in action.

The emergence of self-organized ecoranges generates the potential for highly adaptable responses to environmental perturbations that might affect that ecorange. Within that system, all the plants are consciously and continually communicating with each other, sending chemical communications along the mycelial network to other plants in the community. (Plants also speak using auditory signals through a complex sound-based language that is far more ancient than the human, though it exists in a much subtler sound spectrum than our own.)

If plants in the system detect that another plant in the mycelial network is ill, unique compounds are intelligently generated by the plants most able to do so and sent through the mycelial network to where they are needed. The medicinal compounds in plants have been consciously used for millennia to heal the individual plant, other plants in the ecorange network, and the insects and other animals that make that ecorange home. This kind of conscious plant cooperation, while irritating to kill-or-be-killed reductionists, produces an ecorange much more adaptable to environmental perturbations than would occur if each organism were constantly fighting each other (as neo-Darwinists would have us believe). The old lie that nature is red in tooth and claw, that life is a constant struggle for survival in an implacably hostile environment, just doesn't bear up under close examination, Life-forms die, yes, but they also help other members of their family, and other members of their species, and the members of other species off and on throughout their lifetimes. Just as we do, except they are conscious, intelligent plants.

Within ecoranges, there is a continual exchange of information that flows as volatile chemicals through the air. These chemical exchanges are in fact a highly complex form of plant communication, a language, that is taken in through plant stomata, analyzed, and responded to. There is also a highly complex communication that moves through the soil community, also quite often through the release of volatiles into the immediate rhizosphere surrounding the plant roots. And many chemicals are released into the mycelial network for travel throughout the ecorange. These interactions are highly intelligent and individually generated out of each self-organized plant entity. "The underground roots are," as Baluska et al. comment, "engaged in social activities that require self-awareness." Like bacteria, plants consciously form social communities that are tightly coupled together. And similarly to bacteria, plants show just the same sorts of complex and sophisticated behaviors that humans do, from language, to sentience, to intelligence, to the creation of cities, to cooperation in groups, to complex adaptation to their environment, to protection of offspring, to species memory that is consciously handed down through the generations of plants. And, if the definition of tool is extended, as it should be, to the creation of chemicals that are designed to produce specific impacts on environment, plants capacities include intelligent tool making.

Older plants intelligently send out volatiles to younger plants that contain within them information about chemical responses to predation. A bean plant, being fed upon by a spider mite, can analyze from its saliva just what type of spider mite is feeding on it. It then will craft a specific pheromone, releasing it from its leaf stomata as a volatile chemical into the air. That pheromone will call to the plant the exact predator that feeds on that particular spider mite. Older plants consciously store this information as a kind of cultural learning that is then passed on to younger generations. Old growth plants are repositories of the acquired learning of the species. Cultural learning and transmission is, in reality, common throughout the Gaian system. Chimpanzees teach their young to collect termites with a stick, and how to make the stick-which is harder than it sounds; the stick must be shaped exactly. Scientists who tried to do so, failed... continuously.

The world is made up of a series of highly conscious nested self-organized systems within other nested self-organized systems within other self-organized systems. They, together, make up the much larger system we know as Earth, the living, self-organized biological organism that James Lovelock named Gaia. And all of them are intelligent.
This article on plant consciousness and perception is excerpted from Plant Intelligence and the Imaginal Realm: Beyond the Doors of Perception into the Dreaming of Earth by Stephen Harrod Buhner with permission from the publisher Inner Traditions International. InnerTraditions.com

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Plant Intelligence: New Research Shows Plants Are Just as Smart as Humans

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mountains of research have confirmed that plants have intelligence and even beyond that consciousness by many of the same measures as we do. not only do they feel pain, but plants also perceive and interact with their environment in sophisticated ways.

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Revolutionary Archaeology: the myth of wilderness

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Revolutionary Archaeology: the myth of wilderness

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Humanity has always been part of its ecosystems

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Humanity's transition from hunting and gathering to agriculture is one of the most important developments in human and Earth history. Human societies, plant and animal populations, the makeup of the atmosphere, even the Earth's surface - all were irreversibly transformed.

When asked about this transition, some people might be able to name the Neolithic Revolution or point to the Fertile Crescent on a map. This widespread understanding is the product of years of toil by archaeologists, who diligently unearthed the sickles, grinding stones and storage vessels that spoke to the birth of new technologies for growing crops and domesticating animals. The story they constructed went something like this: beginning in the Near East some 11,000 years ago, humans discovered how to control the reproduction of wheat and barley, which precipitated a rapid switch to farming. Within 500 to 1,000 years, a scattering of small farming villages sprang up, each with several hundred inhabitants eating bread, chickpeas and lentils, soon also herding sheep and goats in the hills, some keeping cattle.

This sedentary lifestyle spread, as farmers migrated from the Fertile Crescent through Turkey and, from there, over the Bosporus and across the Mediterranean into Europe. They moved east from Iran into South Asia and the Indian subcontinent, and south from the Levant into eastern Africa. As farmers and herders populated new areas, they cleared forests to make fields and brought their animals with them, forever changing local environments. Over time, agricultural advances allowed ever larger and denser settlements to flourish, eventually giving rise to cities and civilisations, such as those in Mesopotamia, Egypt, the Indus and later others throughout the Mediterranean and elsewhere.

For many decades, the study of early agriculture centred on only a few other regions apart from the Fertile Crescent. In China, millet, rice and pigs gave rise to the first Chinese cities and dynasties. In southern Mexico, it was maize, squash and beans that were first cultivated and supported later civilisations such as the Olmecs or the Puebloans of the American Southwest. In Peru, native potato, quinoa and llamas were among species domesticated by 5,000 years ago that made later civilisations in the Andes possible. In each of these regions, the transition to agriculture set off trends of rising human populations and growing settlements that required increasing amounts of wood, clay and other raw materials from the surrounding environments.

Yet for all its sweep and influence, this picture of the spread of agriculture is incomplete. New technologies have changed how archaeology is practised, from the way we examine ancient food scraps at a molecular level, to the use of satellite photography to trace patterns of irrigation across entire landscapes. Recent discoveries are expanding our awareness of just how early, extensive and transformative humans' use of land has been. The rise of agriculture was not a 'point in time' revolution that occurred only in a few regions, but rather a pervasive, socioecological shifting back and forth across fuzzy thresholds in many locations.

Bringing together the collective knowledge of more than 250 archaeologists, the ArchaeoGLOBE project in which we participated is the first global, crowdsourced database of archaeological expertise on land use over the past 10,000 years. It tells a completely different story of Earth's transformation than is commonly acknowledged in the natural sciences. ArchaeoGLOBE reveals that human societies modified most of Earth's biosphere much earlier and more profoundly than we thought - an insight that has serious implications for how we understand humanity's relationship to nature and the planet as a whole.

Just as recent archaeological research has challenged old definitions of agriculture and blurred the lines between farmers and hunter-gatherers, it's also leading us to rethink what nature means and where it is. The deep roots of how humanity transformed the globe pose a challenge to the emerging Anthropocene paradigm, in which human-caused environmental change is typically seen as a 20th-century or industrial-era phenomenon. Instead, it's clearer than ever before that most places we think of as 'pristine' or 'untouched' have long relied on human societies to fill crucial ecological roles. As a consequence, trying to disentangle 'natural' ecosystems from those that people have managed for millennia is becoming less and less realistic, let alone desirable.

Our understanding of early agriculture derives mostly from the material remains of food - seeds, other plant remains and animal bones. Archaeologists traditionally document these finds from excavated sites and use them to track the dates and distribution of different people and practices. Over the past several decades, though, practitioners have become more skilled at spotting the earliest signatures of domestication, relying on cutting-edge advances in chemistry, biology, imaging and computer science.

Archaeologists have greatly improved their capacity to trace the evolution of crops, thanks to advances in our capacity to recover minute plant remains - from silica microfossils to attachment scars of cereals, where the seeds attach to the rest of the plant. Along with early crops, agricultural weeds and storage pests such as mice and weevils also appeared. Increasingly, we can identify a broader biotic community that emerged around the first villages and spread with agriculture. For example, weeds that originated in the Fertile Crescent alongside early wheat and barley crops also show up in the earliest agricultural communities in places such as Germany and Pakistan.

Collections of animal bones provide evidence of how herded creatures changed physically through the process of domestication. Butchering marks on bones can help reconstruct culling strategies. From the ages and sizes of animals, archaeologists can deduce the populations of herds in terms of age and sex ratios, all of which reveals how herding differed from hunting. Herding systems themselves also vary, with some focused only on producing meat, and others on milk and wool too.

The British Isles were transformed by imported crops, weeds and livestock from millennia earlier

Measurements of bones and seeds have made great strides with technologies such as geometric morphometrics - complex mathematical shape analysis that allows for a more nuanced understanding of how varieties evolved and moved between regions. Biomolecular methods have also multiplied. The recovery of amino acid profiles from fragmented animal bones, for example, has allowed us to discern which animals they came from, even when they're too degraded for visual identification. The increasingly sophisticated use and analysis of ancient DNA now allows researchers to track the development and distribution of domesticated animals and crops in great detail.

Archaeologists have also used mass spectrometry, a technique involving gas ions, to pinpoint which species were cooked together based on the presence of biomolecules such as lipids. Stable isotopes of carbon and nitrogen from animal bones and seeds give insight into where and how plants and animals were managed - allowing us to more fully sketch out ancient foodwebs from soil conditions to human consumption. Strontium isotopes in human and animal bones, meanwhile, allow us to identify migrations across a single organism's lifetime, revealing more and earlier long-distance interconnections than previously imagined. Radiocarbon dating was already possible in the 1950s - but recent improvements that have reduced sample sizes and error margins allow us to build fine-grained chronologies and directly date individual crops.

With all these fresh data, it's now possible to tell a much richer, more diverse story about the gradual evolutions and dispersals of early agriculture. By 6,000 years ago, the British Isles were being transformed by an imported collection of crops, weeds and livestock that had originated millennia earlier in the Near East. Similarly, millet, rice and pigs from central China had been spread as far as Thailand by 4,000 years ago, and began transforming much of the region's tropical woodland to agricultural fields. New stories are constantly emerging too - including that sorghum, a grain crop, was domesticated in the savannahs of eastern Sudan more than 5,000 years ago, before the arrival of domesticated sheep or goats in that area. Once combined with Near Eastern sheep, goats and cattle, agropastoralism spread rapidly throughout most of sub-Saharan Africa by 2,000 years ago.

Advances in the study of plant silica micro-fossils (phytoliths) have helped trace banana cultivation from the Island of New Guinea more than 7,000 years ago - from where it spread through Island Southeast Asia, and eventually across the Indian Ocean to Africa, more than a millennium before Vasco da Gama navigated from Africa to India. These techniques have also revealed unforeseen agricultural origins - such as the forgotten cereal, browntop millet. It was the first staple crop of South India, before it was largely replaced by crops such as sorghum that were translocated from Africa. Many people might be surprised to learn that the early farming tradition in the Mississippi basin relied on pitseed goosefoot, erect knotweed and marsh elder some 3,000-4,000 years ago, long before maize agriculture arrived in the American Midwest.

Archaeologists don't just study materials painstakingly uncovered in excavations. They also examine landscapes, patterns of settlement, and the built infrastructure of past societies to get a sense of the accumulated changes that humans have made to our environments. They have developed a repertoire of techniques that allow them to study the traces of ancient people on scales much larger than an individual site: from simply walking and documenting the density of broken pottery on the ground, to examining satellite imagery, using lidar (light and laser) and drones to build 3D models, even searching for subsurface magnetic anomalies to plot out the walls of buried cities.

There was usually a long continuum of exploitation, translocation and management of ecosystems

As a result, new revelations about our deep past are constantly emerging. Recent discoveries in southwestern Amazonia showed that people were cultivating squash and manioc more than 10,000 years ago, and maize only a few thousand years later. They did so living in an engineered landscape consisting of thousands of artificial forested islands, within a seasonally flooded savannah.

Some of the most stunning discoveries have come from the application of lidar around Maya cities, buried underneath the tropical canopy in Central America. Lasers can penetrate this canopy to define the shapes of mounds, plazas, ceremonial platforms and long causeways that were previously indistinguishable from the topography of the jungle. A recent example in Mexico pushed back the time period for monumental construction to what we used to consider the very beginning of Maya civilisation - 3,000 years ago - and suggests the monuments were more widespread than previously believed.

These transitions were not linear or absolute. It's now clear that there was usually a long continuum of exploitation, translocation and management of plants, animals, landforms and ecosystems well before (and often after) domestication occurred. This makes it harder to draw solid lines between hunter-gatherer and farmer societies, or between societies who practised different subsistence strategies. Over archaeological timescales spanning hundreds to thousands of years, land use can be thought of instead as a tapestry of ever-evolving anthroecosystems with higher or lower degrees of transformation - more or less human-shaped, or 'domesticated' environments.

In 2003, the climatologist William Ruddiman introduced the 'early anthropogenic hypothesis': the idea that agricultural land use began warming Earth's climate thousands of years ago. While some aspects of this early global climate change remain unsettled among scientists, there's strong consensus that land-use change was the greatest driver of global climate change until the 1950s, and remains a major driver of climate change today. As a result, global maps of historical changes in land use, and their effects on vegetation cover, soils and greenhouse gas emissions, are a critical component of all contemporary models for forecasting Earth's future climate.

Deforestation, tilling the land and other agricultural practices alter regional and global climate because they release greenhouse gases from vegetation and soils, as well as altering the exchange of heat and moisture across Earth. These effects reverse when land is abandoned and vegetation recovers or is restored. Early changes in agricultural land use therefore have major implications in understanding climate changes of the past, present and future.

The main global map of historical land use deployed in climate models is HYDE (the History Database of the Global Environment), combining contemporary and historical patterns of land use and population across the planet over the past 12,000 years. Despite this huge span of space and time, with notable exceptions, HYDE is based largely on historical census data that go back to 1960, mostly from Europe.

HYDE's creator, a collaborator in ArchaeoGLOBE, has long requested help from historians, scientists and archaeologists to build a stronger empirical basis for HYDE's global maps - especially for the deep past, where data are especially lacking. The data needed to improve the HYDE database exist, but reside in a format that's difficult to access - the expert knowledge of archaeologists working in sites and regions around the world. The problem is that no single archaeologist has the breadth or time-depth of knowledge required.

Archaeologists typically study individual regions and time periods, and have only background knowledge on wider areas. Research methods and terminology also aren't standardised worldwide, making syntheses difficult, rare and subjective. To construct a comprehensive global database of past land use, you need to gather information from hundreds of regional specialists and collate it, allowing this mosaic of individual studies to emerge as a single picture. This was exactly what we did for ArchaeoGLOBE.

Earth's terrestrial ecology was already largely transformed by hunter-gatherers, farmers and pastoralists

In 2018, we surveyed more than 1,300 archaeologists around the world, and synthesised their responses into ArchaeoGLOBE. The format of our questionnaire was based on 10 time-slices from history (from 10,000 years ago, roughly the beginning of agriculture, to 1850 CE, the industrial era in Europe); 146 geographic regions; four levels of land-use prevalence; and five land-use categories (foraging/hunting/gathering/fishing; pastoralism; extensive agriculture; intensive agriculture; urbanism).

We ended up receiving 711 regional assessments from 255 individual archaeologists - resulting in a globally complete, if uneven, map of archaeological knowledge. After synthesis and careful analysis, our results (along with 117 other co-authors) were published in 2019 in Science. We also made all our data and analysis available online, at every stage of the research process - even before we had finished collecting it - in an effort to stimulate the culture of open knowledge-sharing in archaeology as a discipline.

The resulting data-trove allows researchers to compare land-use systems over time and in different regions, as well as to aggregate their cumulative, global impacts at different points over the past 10,000 years. When we compared ArchaeoGLOBE results with HYDE, we found that archaeological assessments showed much earlier and more widespread agricultural land use than HYDE suggested - and, therefore, more intensive land use than had been factored into climate change assessments. Indeed, the beginnings of intensive agriculture in ArchaeoGLOBE were earlier than HYDE's across more than half of Earth's current agricultural regions, often by 1,000 years or more.

By 3,000 years ago, Earth's terrestrial ecology was already largely transformed by hunter-gatherers, farmers and pastoralists - with more than half of regions assessed engaged in significant levels of agriculture or pastoralism. For example, the Kopaic Basin in the Greek region of Boeotia was drained and converted from wetland to agricultural land in the 13th century BCE. This plain - roughly 1,500 hectares (15 sq km) in size - surrounded by steep limestone hills, had been a large, shallow lake since the end of the last Ice Age. Late Bronze Age residents of the area, members of what we call the Mycenaean culture, constructed a hydraulic infrastructural system on a massive scale to drain the wetland and claim it for agriculture. They channelised rivers, dug drainage canals, built long dikes and expanded natural sinkholes to direct the water off what would have been nutrient-rich soil. Eventually, when the Mycenaean civilisation collapsed at the end of the Bronze Age, the basin flooded again and returned to its previous wetland state. Legend has it that Heracles filled in the sinkholes as revenge against a local king. The area was not successfully drained again until the 20th century.

These examples highlight a general trend we found that agriculture and pastoralism gradually replaced foraging-hunting-gathering around the world. But the data also show that there were reversals and different subsistence economies, from foraging to farming, operating in parallel in some places. Moreover, agriculture and pastoralism are not the only practices that transform environments. Hunter-gatherer land use was already widespread across the globe (82 per cent of regions) by 10,000 years ago. Through the selective harvest and translocation of favoured species, hunting (sometimes to extinction) and the use of fire to dramatically alter landscapes, most of the terrestrial biosphere was already significantly influenced by human activities, even before the domestication of plants and animals.

ArchaeoGLOBE is both a cause and a consequence of a dramatic change in perspective about how early land use produced long-term global environmental change. Archaeological knowledge is increasingly becoming a crucial instrument for understanding humanity's cumulative effect on ecology and the Earth system, including global changes in climate and biodiversity. As a discipline, the mindset of archaeology stands in contrast to earlier perspectives grounded in the natural sciences, which have long emphasised a dichotomy between humans and nature.

In the 'pristine myth' paradigm from the natural sciences, as the geographer William Denevan called it, human societies are recent destroyers, or at the very least disturbers, of a mostly pristine natural world. Denevan was reacting against the portrayal of pre-1492 America as an untouched paradise, and he used the substantial evidence of indigenous landscape modification to argue that the human presence was perhaps more visible in 1492 than 1750. Recent popular conceptions of the Anthropocene risk making a similar mistake, drawing a thin bright line at 1950 and describing what comes after as a new, modern form of ecological disaster. Human changes to the environment are cumulative and were substantial at different scales throughout our history. The deep trajectory of land use revealed by ArchaeoGLOBE runs counter to the idea of pinpointing a single catalytic moment that fundamentally changed the relationship between humanity and the Earth system.

The pristine myth also accounts for why places without contemporary intensive land use are often dubbed 'wilderness' - such as areas of the Americas depopulated by the great post-Columbian die-off. Such interpretations, perpetuated by scientists, have long supported colonial narratives in which indigenous hunter-gatherer and even agricultural lands are portrayed as unused and ripe for productive use by colonial settlers.

The notion of a pristine Earth also pervaded the thinking of early conservationists in the United States such as John Muir. They were intent on preserving what they saw as the nobility of nature from a mob of lesser natural life, and also those eager to manage wilderness areas to maintain the trophy animals they enjoyed hunting. For example, the governor of California violently forced Indigenous peoples out of Yosemite Valley in the 19th century, making way for wilderness conservation. These ideas went hand-in-hand with a white supremacist view of humanity that cast immigrants and the poor as a type of invasive species. It was not a great leap of theorising to move from a notion of pristine nature to seeing much of humanity as the opposite - a contaminated, marring mass. In both realms, the human and the natural, the object was to exclude undesirable people to preserve bastions of the unspoilt world. These extreme expressions of a dichotomous view of nature and society are possible only by ignoring the growing evidence of long-term human changes to Earth's ecology - humans were, and are still, essential components of most 'natural' ecosystems.

A clear-eyed appreciation for the deep entanglement of the human and natural worlds is vital

Humans have continually altered biodiversity on many scales. We have changed the local mix of species, their ranges, habitats and niches for thousands of years. Long before agriculture, selective human predation of many non-domesticated species shaped their evolutionary course. Even the relatively small hunter-gatherer populations of the late Pleistocene were capable of negatively affecting animal populations - driving many megafauna and island species extinct or to the point of extinction. But there have also been widespread social and ecological adaptations to these changes: human management can even increase biodiversity of landscapes and can sustain these increases for thousands of years. For example, pastoralism might have helped defer climate-driven aridification of the Sahara, maintaining mixed forests and grassland ecosystems in the region for centuries.

This recognition should cause us to rethink what 'nature' and 'wilderness' really are. If by 'nature' we mean something divorced from or untouched by humans, there's almost nowhere on Earth where such conditions exist, or have existed for thousands of years. The same can be said of Earth's climate. If early agricultural land use began warming our climate thousands of years ago, as the early anthropogenic hypothesis suggests, it implies that no 'natural' climate has existed for millennia.

A clear-eyed appreciation for the deep entanglement of the human and natural worlds is vital if we are to grapple with the unprecedented ecological challenges of our times. Naively romanticising a pristine Earth, on the other hand, will hold us back. Grasping that nature is inextricably linked with human societies is fundamental to the worldview of many Indigenous cultures - but it remains a novel and often controversial perspective within the natural sciences. Thankfully, it's now gaining prominence within conservation circles, where it's shifting attitudes about how to enable sustainable and resilient stewardship of land and ecosystems.

Viewing humans and nature as entwined doesn't mean that we should shrug our shoulders at current climatic trends, unchecked deforestation, accelerating extinction rates or widespread industrial waste. Indeed, archaeology supplies numerous examples of societal and ecosystem collapse: a warning of what happens if we ignore the consequences of human-caused environmental change.

But ecological crises are not inevitable. Humans have long maintained sustainable environments by adapting and transforming their societies. As our work demonstrates, humans have shaped the ecology of this planet for thousands of years, and continue to shape it.

We live at a unique time in history, in which our awareness of our role in changing the planet is increasing at the precise moment when we're causing it to change at an alarming rate. It's ironic that technological advances are simultaneously accelerating both global environmental change and our ability to understand humans' role in shaping life on Earth. Ultimately, though, a deeper appreciation of how the Earth's environments are connected to human cultural values helps us make better decisions - and also places the responsibility for the planet's future squarely on our shoulders.

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Revolutionary archaeology reveals the deepest possible Anthropocene - Lucas Stephens, Erle Ellis & Dorian Fuller | Aeon Essays

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Humanity's transition from hunting and gathering to agriculture is one of the most important developments in human and Earth history. Human societies, plant and animal populations, the makeup of the atmosphere, even the Earth's surface - all were irreversibly transformed.

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Interdependency of plants and insects

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Trilliums, bloodroot, violets-many wildflowers of spring in eastern North America bloom thanks to ants. The tiny six-legged gardeners have partnered with those plants as well as about 11,000 others to disperse their seeds. The plants, in turn, "pay" for the service by attaching a calorie-laden appendage to each seed, much like fleshy fruits reward birds and mammals that discard seeds or poop them out. But there's more to the ant-seed relationship than that exchange, researchers reported last week at the annual meeting of the Ecological Society of America, which was held online.

Far from just transporting the seeds, the ants are active gardeners, preferring some seeds over others and possibly keeping their charges safe from disease. "It's becoming clear that it's not a simple two-way interaction," says Douglas Levey, an ecologist at the National Science Foundation.

The importance of this partnership is coming into focus as well. In forests disturbed by human activity, where ants can be scarce, seeds may not find their way to fertile ground, and ecosystems can suffer. "If ants are lost, then there's a real chance that we will lose plants, as well as the other species that depend upon ants and plants," says Judith Bronstein, an evolutionary ecologist at the University of Arizona.

Many ants eat seeds, but in deciduous forests in Europe and North America, Australian dry woodlands, and South African shrublands called fynbos, a few dozen ant species spare the seeds in favor of something better. Certain plants attach a nutritive glob called an elaiosome to their seed coats, which serves as lunch for the ants' young and gives ants a handle on seeds that can be bigger than their head. Until now, researchers assumed the ants simply carry the seeds to their nests, feed the elaiosome to their broods, and deposit the seed either outside or inside at the colony's "garbage dump," which provides a fertile environment for sprouting. But Charles Kwit, an ecologist at the University of Tennessee, Knoxville, thought ants might help seeds with more than just transportation.

The common seed-dispersing ants in the genus Aphaenogaster, like others, secrete antimicrobial chemicals to clean themselves and fellow ants. Kwit wondered how those disinfectants might affect the seeds' microbial communities-and their health. He and his graduate student Chloe Lash teamed up with Melissa Cregger of Oak Ridge National Laboratory to isolate and sequence DNA from microbes on the seed coats of three common ant-dependent plants: wild ginger, bloodroot, and twinleaf. To start, each species' seed had a complex and unique microbiome-its community of bacteria and fungi. But after an ant handled a seed, its microbiome shrank and became more similar to those of other handled seeds of different species, Lash reported at the meeting-apparently because of the antimicrobial treatment. Wild ginger and twinleaf also harbored fewer plant pathogens. The microbiome changes, Levey says, "could affect postdispersal seed predation, dormancy, seed viability, timing of germination, and health of the resulting seedlings."

Kwit's lab has also found that when it comes to seeds, ants have preferences that may influence the plants' success. In both the field and the lab, his student Chelsea Miller presented ants with seeds from various trillium species and found the ants were quick to pick up some species' seeds while leaving others to rot, Miller told the meeting. "So being less preferred really has consequences," Bronstein says.

To find out how ants make their choices, Miller and Susan Whitehead at the Virginia Polytechnic Institute and State University (Virginia Tech) used mass spectroscopy and other techniques to analyze the chemical makeup of elaiosomes. They found that ants pick seeds based on the specific combination and concentrations of oleic acid and other compounds made by the plant, 20 of which are unique to trilliums. The ants' tastes may affect plant species' distributions, says Kirsten Prior, an ecologist at Binghamton University: "Widespread trillium species [are] preferred by seed-dispersing ants compared to rare trillium species."

Human activities, too, can influence ant-seed partnerships. Many researchers assumed ants survive disruptions such as forest clearing and quickly move back into disturbed areas. But Katie Stuble, an ecologist at the Holden Arboretum in Kirtland, Ohio, found otherwise. "Land-use history impacts ant communities," she said at the meeting. Her arboretum covers 1416 hectares, much of it cleared for farmland at different times over the past century before the trees regrew.

Even in areas cleared decades ago, her team found higher concentrations of invasive earthworms and lower concentrations of seed-dispersing ants than in forests that were never cleared. Earthworms break down fallen leaves and organic debris, possibly leaving too little cover for ants. "This suggests that there are huge impacts of past land use that probably run deeper than we previously suspected," Stuble says. Those impacts could explain why secondary forests lack dense undergrowth, and why plants that rely on ants to disperse their seeds are scarce there.

At the meeting, Prior and her student Carmela Buono reported that a survey of 20 sites in northeastern North America showed a similar trend. Compared with never-cleared forests, secondary forests had fewer Aphaenogaster ants, which disperse up to 70% of seeds in a deciduous forest, Buono said. The secondary forests had less leaf litter and fewer decaying logs for ants to colonize. They also had more invasive slugs, which compete with ants by eating the elaiosomes-and leaving seeds behind, rather than dispersing them. The loss of seed-carrying ants "has major implications for forest communities and restoration," Prior says. "To restore understory plant communities, we might also need to think about having to restore this important species interaction." For example, it might help to ensure there are plenty of decaying logs and leaf litter for the ants to thrive in.

Bronstein notes that in the past, ecologists deciphered ants' role as gardeners through painstaking observations. Now, she says, "There are exciting testable hypotheses, well-designed experiments, serious phytochemical analyses, and sophisticated statistical approaches," as well as genome sequencing and fine-scale chemical analyses.

Melissa Burt, an ecologist at Virginia Tech, hopes these studies bring ants new respect. "Many people that I talk to about ants only know them as pests that are taking over their kitchens, but many ants perform important functions in ecosystems," she says. "Seed dispersal is just one of those."

doi:10.1126/science.abe2802

Liz is a senior correspondent covering many aspects of biology for Science.

More from News

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Don't crush that ant-it could plant a wildflower

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Trilliums, bloodroot, violets-many wildflowers of spring in eastern North America bloom thanks to ants. The tiny six-legged gardeners have partnered with those plants as well as about 11,000 others to disperse their seeds. The plants, in turn, "pay" for the service by attaching a calorie-laden appendage to each seed, much like fleshy fruits reward birds and mammals that discard seeds or poop them out.

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Does Consciousness Pervade the Universe?

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Does Consciousness Pervade the Universe?

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Philosopher Philip Goff answers questions about “panpsychism”

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One of science's most challenging problems is a question that can be stated easily: Where does consciousness come from? In his new book Galileo's Error: Foundations for a New Science of Consciousness, philosopher Philip Goff considers a radical perspective: What if consciousness is not something special that the brain does but is instead a quality inherent to all matter? It is a theory known as "panpsychism," and Goff guides readers through the history of the idea, answers common objections (such as "That's just crazy!") and explains why he believes panpsychism represents the best path forward. He answered questions from Mind Matters editor Gareth Cook.

[ An edited transcript of the interview follows.]
Can you explain, in simple terms, what you mean by panpsychism?
In our standard view of things, consciousness exists only in the brains of highly evolved organisms, and hence consciousness exists only in a tiny part of the universe and only in very recent history. According to panpsychism, in contrast, consciousness pervades the universe and is a fundamental feature of it. This doesn't mean that literally everything is conscious. The basic commitment is that the fundamental constituents of reality-perhaps electrons and quarks-have incredibly simple forms of experience. And the very complex experience of the human or animal brain is somehow derived from the experience of the brain's most basic parts.

It might be important to clarify what I mean by "consciousness," as that word is actually quite ambiguous. Some people use it to mean something quite sophisticated, such as self-awareness or the capacity to reflect on one's own existence. This is something we might be reluctant to ascribe to many nonhuman animals, never mind fundamental particles. But when I use the word consciousness, I simply mean experience: pleasure, pain, visual or auditory experience, et cetera.

Human beings have a very rich and complex experience; horses less so; mice less so again. As we move to simpler and simpler forms of life, we find simpler and simpler forms of experience. Perhaps, at some point, the light switches off, and consciousness disappears. But it's at least coherent to suppose that this continuum of consciousness fading while never quite turning off carries on into inorganic matter, with fundamental particles having almost unimaginably simple forms of experience to reflect their incredibly simple nature. That's what panpsychists believe.
You write that you come to this idea as a way of solving a problem in the way consciousness is studied. What, in your mind, is the problem?
Despite great progress in our scientific understanding of the brain, we still don't have even the beginnings of an explanation of how complex electrochemical signaling is somehow able to give rise to the inner subjective world of colors, sounds, smells and tastes that each of us knows in our own case. There is a deep mystery in understanding how what we know about ourselves from the inside fits together with what science tells us about matter from the outside.

While the problem is broadly acknowledged, many people think we just need to plug away at our standard methods of investigating the brain, and we'll eventually crack it. But in my new book, I argue that the problem of consciousness results from the way we designed science at the start of the scientific revolution.

A key moment in the scientific revolution was Galileo's declaration that mathematics was to be the language of the new science, that the new science was to have a purely quantitative vocabulary. But Galileo realized that you can't capture consciousness in these terms, as consciousness is an essentially quality-involving phenomenon. Think about the redness of a red experiences or the smell of flowers or the taste of mint. You can't capture these kinds of qualities in the purely quantitative vocabulary of physical science. So Galileo decided that we have to put consciousness outside of the domain of science; after we'd done that, everything else could be captured in mathematics.

This is really important, because although the problem of consciousness is taken seriously, most people assume our conventional scientific approach is capable of solving it. And they think this because they look at the great success of physical science in explaining more and more of our universe and conclude that this ought to give us confidence that physical science alone will one day explain consciousness. However, I believe that this reaction is rooted in a misunderstanding of the history of science. Yes, physical science has been incredibly successful. But it's been successful precisely because it was designed to exclude consciousness. If Galileo were to time travel to the present day and hear about this problem of explaining consciousness in the terms of physical science, he'd say, "Of course, you can't do that. I designed physical science to deal with quantities, not qualities."
How does panpsychism allow you to approach the problem differently?
The starting point of the panpsychist is that physical science doesn't actually tell us what matter is. That sounds like a bizarre claim at first; you read a physics textbook, you seem to learn all kinds of incredible things about the nature of space, time and matter. But what philosophers of science have realized is that physical science, for all its richness, is confined to telling us about the behavior of matter, what it does. Physics tells us, for example, that matter has mass and charge. These properties are completely defined in terms of behavior, things like attraction, repulsion, resistance to acceleration. Physics tells us absolutely nothing about what philosophers like to call the intrinsic nature of matter: what matter is, in and of itself.

So it turns out that there is a huge hole in our scientific story. The proposal of the panpsychist is to put consciousness in that hole. Consciousness, for the panpsychist, is the intrinsic nature of matter. There's just matter, on this view, nothing supernatural or spiritual. But matter can be described from two perspectives. Physical science describes matter "from the outside," in terms of its behavior. But matter "from the inside"-i.e., in terms of its intrinsic nature-is constituted of forms of consciousness.

What this offers us is a beautifully simple, elegant way of integrating consciousness into our scientific worldview, of marrying what we know about ourselves from the inside and what science tells us about matter from the outside.
What are the objections to this idea that you hear most frequently? And how do you respond?
Of course, the most common one is "That's just crazy!" But many of our best scientific theories are wildly counter to common sense, too-for example, Albert Einstein's theory that time slows down when you travel very fast or Charles Darwin's theory that our ancestors were apes. At the end of the day, you should judge a view not by its cultural associations but by its explanatory power. Panpsychism gives us a way of resolving the mystery of consciousness, a way that avoids the deep difficulties that plague more conventional options.
Do you foresee a scenario in which panpsychism can be tested?
There is a profound difficulty at the heart of the science of consciousness: consciousness is unobservable. You can't look inside an electron to see whether or not it is conscious. But nor can you look inside someone's head and see their feelings and experiences. We know that consciousness exists not from observation and experiment but by being conscious. The only way we can find out about the consciousness of others is by asking them: I can't directly perceive your experience, but I can ask you what you're feeling. And if I'm a neuroscientist, I can do this while I'm scanning your brain to see which bits light up as you tell me what you're feeling and experiencing. In this way, scientists are able correlate certain kinds of brain activity with certain kinds of experience. We now know which kinds of brain activity are associated with feelings of hunger, with visual experiences, with pleasure, pain, anxiety, et cetera.

This is really important information, but it's not itself a theory of consciousness. That's because what we ultimately want from a science of consciousness is an explanation of those correlations. Why is it that, say, a certain kind of activity in the hypothalamus is associated with the feeling of hunger? Why should that be so? As soon as you start to answer this question, you move beyond what can be, strictly speaking, tested, simply because consciousness is unobservable. We have to turn to philosophy.

The moral of the story is that we need both the science and the philosophy to get a theory of consciousness. The science gives us correlations between brain activity and experience. We then have to work out the best philosophical theory that explains those correlations. In my view, the only theory that holds up to scrutiny is panpsychism.
How did you become interested in this topic?
When I studied philosophy, we were taught that there were only two approaches to consciousness: either you think consciousness can be explained in conventional scientific terms, or you think consciousness is something magical and mysterious that science will never understand. I came to think that both of these views were pretty hopeless. I think we can have hope that we will one day have a science of consciousness, but we need to rethink what science is. Panpsychism offers us a way of doing this.

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Does Consciousness Pervade the Universe?

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One of science's most challenging problems is a question that can be stated easily: Where does consciousness come from? In his new book Galileo's Error : Foundations for a New Science of Consciousness , philosopher Philip Goff considers a radical perspective: What if consciousness is not something special that the brain does but is instead a quality inherent to all matter?

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Short succinct article on where the climate change narrative went wrong

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WHEN JIMMY CARTER ASKED scientist Charles Keeling for advice in 1978 on what the government should do about climate change, Keeling said that the problem was far too complicated for people to understand, so focus on greenhouse emissions. Since then, reducing greenhouse emissions has been the principal focus for those interested in reducing their environmental impact. While greenhouse emissions must be reduced, new science is showing us that expanding our focus to restoring natural ecosystems could ameliorate the effects of rising greenhouse gases on global temperature increases.

While greenhouse emissions do increase the planet's energy load, that energy does not need to cause temperature rise (sensible heat). When solar energy falls on moist surfaces or living plants, it produces evaporation or evapotranspiration (latent heat), increasing humidity, not temperature.

It is this hydrologic cooling that forests and other living plants create that prompted David Ellison and 22 other researchers to state, "Forests and trees must be recognized as prime regulators within the water, energy and carbon cycles...." They call for a "reversal of paradigms, from a carbon-centric (greenhouse) model to one that treats the hydrologic and climate-cooling effects of trees and forests as the first order of priority."

The earth's rotation creates a lateral circulation of moisture known as the "large water cycle." Evaporation from the oceans accounts for 86% of the atmospheric moisture, but 26% of that falls onto the land. Therefore, the land contributes 14% of the evaporation but receives nearly twice that much back as rain or snow. Thus, the world's rivers run to the sea, yet the sea level did not rise as it is rising now.

A "small water cycle," a vertical generator of mild, local weather, operates within each watershed. The critical term here is vertical. Small water cycles need to recycle water within the watershed in order to maintain the local ecology, as moist environments attract more moisture and dry environments repel it. Humans violate this law of nature by draining away "waste-water." Each turn in the affected water cycle slightly decreases the amount of water that cycles within it.

But unnatural drainage is not the only problem. Soil naturally holds water in relation to the amount of organic matter it contains. An increase of one percent of carbon in soil will increase the water-holding capacity by 20,000 gallons per acre. As industrial agriculture, with tillage and chemicals, degrades the soil we inherited to "dirt," water drains from the land, no longer able to hold it. Studies have documented whole countries drying out over decades due to this man-made manipulation.Besides holding-capacity, soil health also has dramatic impacts on percolation rates, determining how much rainwater soaks into the ground, affecting flooding and how quickly it runs off, causing erosion.

Desertification shifts rain patterns, decreasing rainfall on lower elevations and increasing it in higher elevations. This breaks the small water cycle and allows the more violent large water cycle to predominate, leading to more severe storms with flooding and associated damage, but blinds residents to the fact that their country is undergoing desertification.

The human settlements that date back to the dawn of the agricultural era, such as those in the Middle East, northern Africa, India, and China, are now largely deserts due to deforestation, agriculture and urbanization. Despite the evidence, we have not rethought our impact on climate systems. These common practices decrease evapotranspiration, which causes increased temperatures (sensible heat) and increased temperature divergence.

Human actions have created deserts, but we must look beyond greenhouse emissions to a systemic understanding of biological systems to begin the healing.

Brown, G, (2018). T he Farm as an Ecosystem. Worcester MA: Worcester State University:.

Ellison D, Morris C, Locatelli B et al. (2017). Trees, Forests and Water: Cool Insights for a Hot World. Global Environmental Change 43: 51-61.

Griffith, B, (2001). The Gardens of their Dreams: Desertification and Culture in World History. Halifax, Nova Scotia: Fernwood Publishing.

Jehne W, (2015). The Natural History of Water on Earth. Medford, MA: Tufts University:.

Kravcik M, Pokorny J, Kohutiar J et al. (2008) Water for the Recovery of the Climate: A New Water Paradigm. Typopress-publishing House.
Christopher Haines is QEW's Yearly Meeting Representative to New England Yearly Meeting.

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WHEN JIMMY CARTER ASKED scientist Charles Keeling for advice in 1978 on what the government should do about climate change, Keeling said that the problem was far too complicated for people to understand, so focus on greenhouse emissions. Since then, reducing greenhouse emissions has been the principal focus for those interested in reducing their environmental impact.

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The biotic pump

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There are a few different levels of understanding about the water cycle. There are the diagrams hung in elementary schools, showing water evaporating up from the ocean into clouds, then falling back down to the ground. A step beyond, there's a general understanding that takes into account evaporation from trees, wind patterns and the like.

Then, there are the highly technical approaches that look at a wild array of minutia and contingencies: nighttime sap flow, isoprene emissions, ice-nucleating particles released from decaying leaves, even the phases of the moon.

And yet, even with all of these details researched and logged and plugged into different models and algorithms, it's hard to trust a given morning's forecast. Cloud behavior and rainfall still remains a mystery - let alone how they will react with climate change.

"The models just don't do this," says Center for International Forestry Research (CIFOR) Associate Douglas Sheil, who also serves as faculty of environmental sciences and natural resource management at the Norwegian University of Life Sciences. "And the problem is that we're using these models to predict climate change, when they can't even predict current rainfall patterns correctly."

Taking progress on this matter into his own hands, Sheil has recently published a paper that seeks to show why such mysteries still exist and point out areas where research is needed in order to solve them. In simple, readable language, he summarizes the most prevalent water cycle theories and hypothesizes the enormous change that could happen, should we finally agree upon one that works - perhaps even his own.
PUMP UP
Like calculating numerical probabilities for dice rolled many times versus guessing the value of a single toss, climate patterns can be more consistently predicted than the weather. We know, more or less, that after winter comes spring; we don't know exactly how hot next weekend will be. However, when it comes to how rain fits in, Sheil is of the belief that there isn't an agreed-upon water cycle theory that helps predict either short- or long-term events - and he isn't alone.

The water cycle was a popular research topic in the early 1900s, with scientists already noticing how deforestation led to changes in rainfall and weather. A dip in interest occurred in the middle part of the century, led by coastal populations brushing off freak weather events as having simply blown in off the ocean.

However, as the weather has gotten more erratic and global social issues starker, the past 10-15 years have seen scientists revisit the water cycle in spades, recognizing it as something we must understand. Between 1992 and 2015, for instance, the world's freshwater resources divided by the global population declined by 25%, and reliable access has declined too - apparent in catastrophic events like the Ethiopian drought of 2015.

As the water cycle comes back into focus, it's bringing forests along with it this time. "Everyone knows forests are important for rainfall. That's not news," says Sheil. "But I think what is news is the extent to which they matter, and that the sharpness and clarity of those links are becoming so much better understood - just in the past few years.

Approximately 117,600 cubic kilometers of water falls to the earth as precipitation each year. Sixty-one percent of this comes from land, and more than half of that comes from plant transpiration. A different recent study found that land cover changes have already caused a 5-6% reduction in global atmospheric moisture. "The sum emission of water vapor from forests (transpiration and evaporation) typically surpasses that from other vegetation and open water," states Sheil's article.

A number of theories take into account the role of forests in the water cycle, beginning with the temperature-gradient theory, developed by Isaac Newton's contemporary Edmund Halley in 1686. Linking winds and global circulation to the temperature patterns of air cooling over sea and warming over land, this theory and others like it remain preeminent, and research continues on the effect of forests within this framework.

However, as Sheil explains in his paper, such a temperature-driven theory can't explain various features of the weather, such as abrupt shifts in monsoon climates, why rainfall is maintained in certain areas but not in others, and why places like the Amazon Basin and Indonesia attract so much rain.

In 2008, Sheil became interested in and joined the research endeavors around a novel approach to the water cycle that physicists Anastassia Makarieva and Victor Gorshkov had developed, named the 'biotic pump'. Rather than focusing on temperature alone, the pump takes into account how water condensation and evaporation influences air pressure, which creates rainfall patterns. When moisture condenses or freezes - forming clouds or rain drops - the air tends to rise and atmospheric pressure below it drops, drawing the surrounding air in and up so that the moisture in this air also tends to condense or freeze, fueling the process.

Through this approach, the biotic pump can better describe the role of forests in the water cycle. Emitting moisture as they do, trees initially raise air pressure in the atmosphere around them. This is reversed once rain starts to fall.

"A lot of people assume that a new theory is really radical and sophisticated, but the basic idea behind this is just school physics," he says. This caveat, though, might undermine the fact that the pump has since proven itself repeatedly by predicting various relationships in climate and weather.

"My colleagues and I conducted a study that we published as an article, predicting and showing that air pressure will often increase before rain in the Amazon. In the standard temperature theory you'd just expect low pressure prior to rain, but that is not what we see. The pump theory was able to make this unique prediction of a physical relationship. So, making predictions that others wouldn't predict and then showing that they work - that's science."
WET AS THE DESERT
Aside from giving guidance on when to carry an umbrella, a better understanding of the water cycle can potentially equip scientists with the ability to institute massive continental change.

This begins with understanding the water cycle fundamentals underpinning all the theories, that being: water is drawn up from the soil and elsewhere, emitted into the atmosphere, and falls back to earth as rain several times before it makes it out to sea.

"Trees re-emit water that then falls somewhere else," says Sheil. "A little patch of trees may use more water than the surrounding landscape, but the larger landscape overall will likely have higher rainfall. These things happen at different scales."

Zoom out, and this applies across regions as well, with rainfall losses in one place serving as gains in another.

"I highlight that farmers in China are very dependent on what land users in Europe and Africa are doing, because that's where most of their rainfall is coming from."

On a very generous scale of geography and time, this potentially means that with an understanding of the water cycle guiding strategic planting of trees, it could be possible to turn dry landscapes wet, and vice versa. Such a new understanding would inform where to plant forests that channel rainfall to dry areas, and then once those dry areas have enough natural irrigation, forests can be planted that will re-wet themselves.

"A potential way to re-green the Sahara... It sounds bizarre and crazy, but it could actually be practical if you get the resources and time to do it. That's pretty exciting. I think starting in coastal areas and then moving inland over the long-term, these things could be possible."

But the first step to doing so, he says, is to stop debating and start researching, to prove whether the biotic pump is true, or develop something else that is. The point of Sheil's research is to stoke the research world into finally landing upon an understanding of the water cycle that works, so that it can be used to bring water to the places that need it most.

"If the biotic pump is true, we shouldn't be arguing about it. We shouldn't be wasting another 10 years, while it actually tells us what's at risk and could bring solutions to people who are suffering from water shortages. This has scary aspects - like high-rainfall landscapes switching rapidly to dryland due to forest loss - but, amazingly positive aspects too."

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Figuring out the water cycle... still - CIFOR Forests News

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There are a few different levels of understanding about the water cycle. There are the diagrams hung in elementary schools, showing water evaporating up from the ocean into clouds, then falling back down to the ground. A step beyond, there's a general understanding that takes into account evaporation from trees, wind patterns and the like.

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Attenborough meets 'trees that care for each other'

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Attenborough meets 'trees that care for each other'

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The veteran broadcaster, 93, will front the landmark BBC One series, which will track 'remarkable new behaviour' and even 'emotional stories'

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Attenborough meets 'trees that care for each other'

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The veteran broadcaster, 93, will front the landmark BBC One series, which will track 'remarkable new behaviour' and even 'emotional stories'.

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Viktor Schauberger - Comprehend and Copy Nature

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Viktor Schauberger - Comprehend and Copy Nature

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Implosion technologies,  forest systems and hydrological cycles

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Viktor Schauberger - Comprehend and Copy Nature (Documentary of 2008)

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Nectar becomes sweeter when bees are heard

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Even on the quietest days, the world is full of sounds: birds chirping, wind rustling through trees, and insects humming about their business. The ears of both predator and prey are attuned to one another's presence.

Sound is so elemental to life and survival that it prompted Tel Aviv University researcher Lilach Hadany to ask: What if it wasn't just animals that could sense sound-what if plants could, too? The first experiments to test this hypothesis, published recently on the pre-print server bioRxiv, suggest that in at least one case, plants can hear, and it confers a real evolutionary advantage.

Hadany's team looked at evening primroses ( Oenothera drummondii) and found that within minutes of sensing vibrations from pollinators' wings, the plants temporarily increased the concentration of sugar in their flowers' nectar. In effect, the flowers themselves served as ears, picking up the specific frequencies of bees' wings while tuning out irrelevant sounds like wind.

As an evolutionary theoretician, Hadany says her question was prompted by the realization that sounds are a ubiquitous natural resource-one that plants would be wasting if they didn't take advantage of it as animals do. If plants had a way of hearing and responding to sound, she figured, it could help them survive and pass on their genetic legacy.

Since pollination is key to plant reproduction, her team started by investigating flowers. Evening primrose, which grows wild on the beaches and in parks around Tel Aviv, emerged as a good candidate, since it has a long bloom time and produces measurable quantities of nectar.

To test the primroses in the lab, Hadany's team exposed plants to five sound treatments: silence, recordings of a honeybee from four inches away, and computer-generated sounds in low, intermediate, and high frequencies. Plants given the silent treatment-placed under vibration-blocking glass jars-had no significant increase in nectar sugar concentration. The same went for plants exposed to high-frequency (158 to 160 kilohertz) and intermediate-frequency (34 to 35 kilohertz) sounds.

But for plants exposed to playbacks of bee sounds (0.2 to 0.5 kilohertz) and similarly low-frequency sounds (0.05 to 1 kilohertz), the final analysis revealed an unmistakable response. Within three minutes of exposure to these recordings, sugar concentration in the plants increased from between 12 and 17 percent to 20 percent.

A sweeter treat for pollinators, their theory goes, may draw in more insects, potentially increasing the chances of successful cross-pollination. Indeed, in field observations, researchers found that pollinators were more than nine times more common around plants another pollinator had visited within the previous six minutes.

"We were quite surprised when we found out that it actually worked," Hadany says. "But after repeating it in other situations, in different seasons, and with plants grown both indoors and outdoors, we feel very confident in the result."

As the team thought about how sound works, via the transmission and interpretation of vibrations, the role of the flowers became even more intriguing. Though blossoms vary widely in shape and size, a good many are concave or bowl-shaped. This makes them perfect for receiving and amplifying sound waves, much like a satellite dish.

To test the vibrational effects of each sound frequency test group, Hadany and her co-author Marine Veits, then a graduate student in Hadany's lab, put the evening primrose flowers under a machine called a laser vibrometer, which measures minute movements. The team then compared the flowers' vibrations with those from each of the sound treatments.

"This specific flower is bowl- shaped, so acoustically speaking, it makes sense that this kind of structure would vibrate and increase the vibration within itself," Veits says.

And indeed it did, at least for the pollinators' frequencies. Hadany says it was exciting to see the vibrations of the flower match up with the wavelengths of the bee recording.

"You immediately see that it works," she says.

To confirm that the flower was the responsible structure, the team also ran tests on flowers that had one or more petals removed. Those flowers failed to resonate with either of the low-frequency sounds.

What else plants can hear

Hadany acknowledges that there are many, many questions remaining about this newfound ability of plants to respond to sound. Are some "ears" better for certain frequencies than others? And why does the evening primrose make its nectar so much sweeter when bees are known to be able to detect changes in sugar concentration as small as 1 to 3 percent?

Also, could this ability confer other advantages beyond nectar production and pollination? Hadany posits that perhaps plants alert one another to the sound of herbivores mowing down their neighbors. Or maybe they can generate sounds that attract the animals involved in dispersing that plant's seeds.

"We have to take into account that flowers have evolved with pollinators for a very long time," Hadany says. "They are living entities, and they, too, need to survive in the world. It's important for them to be able to sense their environment-especially if they cannot go anywhere."

This single study has cracked open an entirely new field of scientific research, which Hadany calls phytoacoustics.

Veits wants to know more about the underlying mechanisms behind the phenomenon the research team observed. For instance, what molecular or mechanical processes are driving the vibration and nectar response? She also hopes the work will affirm the idea that it doesn't always take a traditional sense organ to perceive the world.

"Some people may think, How can [plants] hear or smell?" Veits says. "I'd like people to understand that hearing is not only for ears."

Richard Karban, an expert in interactions between plants and their pests at the University of California Davis, has questions of his own, in particular, about the evolutionary advantages of plants' responses to sound.

"It may be possible that plants are able to chemically sense their neighbors, and to evaluate whether or not other plants around them are fertilized," he says. "There's no evidence that things like that are going on, but [this study] has done the first step."

Editor's Note: This story has been updated to correct the percent increase in nectar's sugar concentration.

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Flowers can hear buzzing bees-and it makes their nectar sweeter

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Even on the quietest days, the world is full of sounds: birds chirping, wind rustling through trees, and insects humming about their business. The ears of both predator and prey are attuned to one another's presence.

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Researchers find nature's backup plan for converting nitrogen into plant nutrients

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Researchers find nature's backup plan for converting nitrogen into plant nutrients

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Discovery of vanadium-based nitrogenases

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Although nitrogen is essential for all living organisms -- it makes up 3% of the human body -- and comprises 78% of Earth's atmosphere, it's almost ironically difficult for plants and natural systems to access it.

Atmospheric nitrogen is not directly usable by most living things. In nature, specialized microbes in soils and bodies of water convert nitrogen into ammonia -- a crucial form of nitrogen that life can easily access -- through a process called nitrogen fixation. In agriculture, soybeans and other legumes that facilitate nitrogen fixation can be planted to restore soil fertility.

An additional obstacle in the process of making nitrogen available to the plants and ecosystems that rely on it is that microbial nitrogen "fixers" incorporate a complex protein called nitrogenase that contains a metal-rich core. Existing research has focused on nitrogenases containing a specific metal, molybdenum.

The extremely small amount of molybdenum found in soil, however, has raised concerns about the natural limits of nitrogen fixation on land. Scientists have wondered what restrictions the scarcity of molybdenum places on nature's capacity to restore ecosystem fertility in the wake of human-made disturbances, or as people increasingly search for arable land to feed a growing population.

Princeton University researchers have found evidence that other metals can facilitate nitrogen fixation when molybdenum is scarce, which suggests that the process may be more resilient than previously thought, according to a study published in the journal Proceedings of the National Academy of Sciences. Working in a 372 mile (600 kilometer) stretch of boreal forest in Canada, the researchers found that nitrogen fixation at an ecosystem scale can also be catalyzed by the metal vanadium, particularly in northern regions with limited natural nitrogen inputs.

"This work prompts a major revision of our understanding of how micronutrients control ecosystem nitrogen status and fertility," said senior author Xinning Zhang, assistant professor of geosciences and the Princeton Environmental Institute.

"We need to know more about how nitrogen fixation manifests in terms of nutrient budgets, cycling and biodiversity," she said. "One consequence of this finding is that current estimates of the amount of nitrogen input into boreal forests through fixation may be significantly underestimated. This is a major issue for our understanding of nutrient requirements for forest ecosystems, which currently function as an important sink for anthropogenic carbon."

First author Romain Darnajoux, a postdoctoral research associate in Zhang's research group, explained that the findings validate a long-held hypothesis in the scientific community that different metal variants of nitrogenase exist so that organisms can cope with changes in metal availability. The researchers found that vanadium-based nitrogen fixation was only substantive when environmental molybdenum levels were low.

"It would seem that nature evolved backup methods to sustain ecosystem fertility when the environment is variable," Darnajoux said. "Every nitrogen-cycle step involves an enzyme that requires particular trace metals to work. Molybdenum and iron are typically the focus of scientific study because they're considered to be essential in the nitrogen fixing enzyme nitrogenase. However, a vanadium-based nitrogenase also exists, but nitrogen input by this enzyme has been unfortunately largely ignored."

Darnajoux and Zhang worked with Nicolas Magain and Franc?ois Lutzoni at Duke University and Marie Renaudin and Jean-Philippe Bellenger at the University of Sherbrooke in Québec.

The researchers' results suggest that the current estimates of nitrogen input into boreal forests through fixation are woefully low, which would underestimate the nitrogen demand for robust plant growth, Darnajoux said. Boreal forests help mitigate climate change by acting as a sink for anthropogenic carbon. Though these northern forests do not see as many human visitors as even the most lightly populated metropolis, human activities can still have major impacts on forest fertility through the atmospheric transport of air pollution loaded with nitrogen and metals such as molybdenum and vanadium.

"Human activities that substantially change air quality can have a far reaching influence on how even remote ecosystems function," Zhang said. "The findings highlight the importance of air pollution in altering micronutrient and macronutrient dynamics. Because air is a global commons, the connection between metals and nitrogen cycling and air pollution has some interesting policy and management dimensions."

The researchers findings could help in the development of more accurate climate models, which do not explicitly contain information on molybdenum or vanadium in simulations of the global flow of nitrogen through the land, ocean and atmosphere.

The importance of vanadium-driven nitrogen fixation extends to other high latitude regions, and most likely to temperate and tropical systems, Darnajoux and Zhang said. The threshold for the amount of molybdenum an ecosystem needs to activate or deactivate vanadium nitrogen fixation that they found in their study was remarkably similar to the molybdenum requirements of nitrogen fixation found for samples spanning diverse biomes.

The researchers will continue the search for vanadium-based nitrogen fixation in the northern latitudes. They've also turned their eyes toward areas closer to home, initiating studies of micro- and macronutrient dynamics in temperate forests in New Jersey, and they plan to expand their work to tropical systems.

###

The paper, "Molybdenum threshold for ecosystem-scale alternative vanadium nitrogenase activity in boreal forests," was published by the Proceedings of the National Academy of Sciences online in-advance of print on Nov. 11. This work was supported by a Life Sciences Postdoctoral Fellowship from the Simons Foundation, the Natural Sciences and Engineering Research Council of Canada (grant RGPIN-2016-03660), the Canadian Research Chair in Boreal Biogeochemistry (CRC-950-230570), and a National Science Foundation Geobiology and Low-Temperature Geochemistry award (EAR-1631814), a Dimensions of Biodiversity award (DEB-1046065), and a Phylogenetic Systematics award (DEB-1556995).

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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Researchers find nature's backup plan for converting nitrogen into plant nutrients

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Princeton University researchers have found that nature has developed a backup method for converting atmospheric nitrogen into the nutrient form critical to plant growth and soil fertility. The researchers report that the process known as nitrogen fixation can be carried out by the metal vanadium in ecosystems where the primary catalyst molybdenum is scarce.

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Mushrooms as Rainmakers: How Spores Act as Nuclei for Raindrops

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Mushrooms as Rainmakers: How Spores Act as Nuclei for Raindrops

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Millions of tons of fungal spores are dispersed in the atmosphere every year. These living cells, along with plant spores and pollen grains, may act as nuclei for condensation of water in clouds

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Maribeth O. Hassett,

Mark W. F. Fischer,

Nicholas P. Money

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Abstract

Millions of tons of fungal spores are dispersed in the atmosphere every year. These living cells, along with plant spores and pollen grains, may act as nuclei for condensation of water in clouds. Basidiospores released by mushrooms form a significant proportion of these aerosols, particularly above tropical forests. Mushroom spores are discharged from gills by the rapid displacement of a droplet of fluid on the cell surface. This droplet is formed by the condensation of water on the spore surface stimulated by the secretion of mannitol and other hygroscopic sugars. This fluid is carried with the spore during discharge, but evaporates once the spore is airborne. Using environmental electron microscopy, we have demonstrated that droplets reform on spores in humid air. The kinetics of this process suggest that basidiospores are especially effective as nuclei for the formation of large water drops in clouds. Through this mechanism, mushroom spores may promote rainfall in ecosystems that support large populations of ectomycorrhizal and saprotrophic basidiomycetes. Our research heightens interest in the global significance of the fungi and raises additional concerns about the sustainability of forests that depend on heavy precipitation.

Citation: Hassett MO, Fischer MWF, Money NP (2015) Mushrooms as Rainmakers: How Spores Act as Nuclei for Raindrops. PLoS ONE 10(10): e0140407. https://doi.org/10.1371/journal.pone.0140407

Editor: Amy S. Gladfelter, Dartmouth College, UNITED STATES

Received: July 16, 2015; Accepted: September 24, 2015; Published: October 28, 2015

Copyright: © 2015 Hassett et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Data Availability: All relevant data are within the paper and its Supporting Information files.

Funding: The authors received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Million of tons of fungal spores are dispersed in the atmosphere every year [ 1]. An individual gilled mushroom can release 30,000 basidiospores every second, corresponding to a daily output of billions of microscopic particles [ 2]. Basidiospores are discharged from the gill surfaces by a catapult mechanism powered by the rapid movement of a drop of fluid over the spore surface ( Fig 1). This fluid is called Buller's drop in tribute to "the Einstein of Mycology," A. H. R. Buller (1874-1944). Buller's drop is formed by the condensation of water on the spore surface that is stimulated by the secretion of mannitol and other hygroscopic sugars [ 3, 4]. Water also condenses on a spot on the adjacent spore surface. The merger of Buller's drop with this second volume of fluid (the adaxial drop) causes a rapid displacement of the center of mass of the spore. This fluid motion, driven by surface tension, imparts momentum to the spore and it is launched at an initial velocity of up to 1.8 m s-1 [ 5]. This mechanism was proposed in some detail in the 1980s [ 6], and verified later by high-speed video recordings [ 7].

Buller's drop and the adaxial drop form via condensation of water on the spore surface and their coalescence causes a rapid shift in the center of mass of the spore that is responsible for the launch.

Discharged spores fall in the narrow spaces between the gills and are dispersed in airflow around the mushroom cap. The same discharge mechanism operates in poroid mushrooms, with fertile tubes rather than gills, in mushrooms with spines, and from the great diversity of fruit bodies that form spores on exposed surfaces. Fluid is carried with basidiospores after discharge, but evaporates once the spore is airborne. Mushroom spores are a primary source of mannitol detected in air samples above tropical forests [ 1]. Using mannitol as a biotracer, Elbert et al. (2007) estimated that 50 million tonnes of spores are dispersed in the atmosphere every year. This biomass is carried by an Avogadroian number of spores, corresponding to an average of 1,000 spores for every square millimeter of Earth's surface. Other biogenic aerosols include plant spores and pollen grains. These "primary biological aerosol particles" appear to be particularly important in the Amazon Basin, and other densely forested locations, where they may serve as nuclei for cloud formation and precipitation [ 8]. Details of the hygroscopic behavior of mushroom spores have not been studied previously.

Environmental scanning electron microscopy (ESEM) has been used in a number of experiments to study the condensation of water on pollen and other particles that become aerosolized [ 9- 13]. This technique allows investigators to study the properties of untreated biological samples to preserve natural surface chemistry and to visualize the condensation of water in real time. In the present study, we report ESEM experiments showing that the extraordinary mechanism of spore discharge in mushrooms has a specific effect on water condensation after spores are dispersed in the atmosphere. This suggests that mushroom spores are particularly powerful catalysts for raindrop formation in clouds and contribute to rainfall. This may be an important phenomenon in ecosystems that support large populations of ectomycorrhizal and saprotrophic basidiomycetes. Our research heightens interest in the global significance of the fungi and raises additional concerns about the sustainability of forests that depend on heavy rainfall.

Materials and Methods

Fungal specimens

Fresh specimens of basidiomycete fruit bodies were collected from the Miami University Natural Areas in Oxford, Ohio ( Fig 2). Permits are not required for collecting specimens from these woodlands and none of the fungi are listed as protected or endangered species. These species included gilled and poroid mushrooms whose spores are discharged via the drop mechanism (species of Lactarius, Russula, and Suillus), and a puffball ( Lycoperdon pyriforme) and earth-star ( Geastrum saccatum) whose spores are expelled from the fruit body by the impact of raindrops. Gilled and poroid mushrooms were positioned above ESEM aluminum stubs to allow a fine deposit of spores to accumulate for 1-4 h. The puffball and earth-star spores were deposited on the ESEM stubs by gentle squeezing of the fruit bodies to cause puffing. The spores were not treated with any chemicals prior to imaging.

Environmental Scanning Electron Microscopy (ESEM)

Samples were analyzed using an environmental scanning electron microscope (FEI Quanta 200 ESEM, Hillsboro, OR). Non-coated stubs carrying the spore deposits were mounted on a Peltier cooling stage inside the microscope and the temperature was stabilized at 3 C. The relative humidity inside the sample chamber was controlled by maintaining a constant temperature and altering the vapor pressure (Hiranuma et al. 2008). This provides conditions of supersaturation inside the specimen chamber according to the Clausius-Clapyron equation [ 14]:

RH = relative humidity

P = pressure in torr

P S = saturated vapor pressure at 273.15°C = 4.58 torr

L V = latent heat of vaporization of water = 2.26 x 10 6 J kg-1

R V = Gas constant for water vapor = 461.5 J/(kg K)

T C = temperature in °C

For the analysis of hygroscopic behavior, each spore deposit of each species was subjected to 2-4 repetitions of identical changes relative humidity.

Results

Dynamics of drop formation

Spores with prominent hilar appendices from gilled and poroid mushrooms were studied under conditions of increasing relative humidity (RH) using the ESEM. Water droplets developed on the hilar appendix ( Fig 3) and on the adaxial surface ( Fig 4) of these spores between relative humidities of 101% and 102%. Image sequences were captured showing the spore surface prior to droplet initiation, formation of the initial droplets, and subsequent expansion of droplets (Figs 3 and 4, S1 Video and S2 Video). These experiments show that Buller's drop and the adaxial drop can reform on the spore after discharge.

(A, D) Spore prior to droplet formation with hilar appendix appearing as rounded protruberance from the base of the spore. (B, E) Droplet beginning to form, and (C, F) continuing to expand. Scale = 2 μm.

(A-C) Lactarius hygrophoroides, (D-F) Russula pulchra. The spores in this figure are viewed in profile with the hilar appendix protruding from the base and the adaxial surface above (arrows). (A-C) 103% RH; (D) 98% RH; (E,F) 102% RH. Scale = 5 μm.

The sensitivity to drop expansion on the hilar appendix and adaxial surface of the spores was demonstrated by controlling the RH inside the sample chamber by increasing or decreasing the water vapor pressure within the sample chamber of the microscope ( Fig 5). Water condensing on the spore forms large droplets when RH is increased to 102% RH, and shrinks when it is dropped below 100% RH, appearing as a thin film on the spore surface before complete evaporation. New drops were generated on the same spores after multiple rounds of dehydration and rehydration.

Several factors dictate the maximum size of Buller's drop and the adaxial drop during spore discharge. Buller's drop is constrained by spore size and geometry, hydrophobicity of spore surface, and the growth of the adaxial drop with which it fuses [ 5, 15]. In the ESEM experiments, droplets were observed growing from the hilar appendix, and from the adaxial surface, but not from both parts of the same spore surface simultaneously. The maximum size of droplets growing from the hilar appendix of spores is comparable to those predicted from spore dimensions [ 5, 15] and associated with normal spore discharge ( Fig 3). Droplets growing from the adaxial surface of spores became much larger, with the diameter of droplets often exceeding the diameter of the spore ( Fig 6). The largest drops associated with single spores expanded to a diameter of 13 μm and 27 μm drops surrounded clusters of three spores.

(A-D) Spores are orientated with adaxial surface facing away from surface of the specimen stub, allowing observation of droplets growing from this hygroscopic region of the spore. Note merger of droplets in second and third panels. Scale = 5 μm.

Behavior of non-ballistosporic basidiospores

There were significant differences in the pattern of water condensation on the surface of non-ballistosporic basidiospores of Lycoperdon pyriforme and Geastrum saccatum. As the vapor pressure in the ESEM specimen chamber was increased to boost the RH from 100% to 102%, liquid water began to accumulate on the spores, but formed a thin shell around the entire spore rather than expanding as discrete droplets. This accumulation of water was visible as a thin halo around each spore ( Fig 7). This behavior contrasts with the expansion of droplets on the surface of ballistospores that often exceeded the size of the spores.

(A) Spore prior to condensation of water at 100% RH and (B) with halo of water surrounding the spore at 101% RH. Scale = 2 μm.

Discussion

Drop growth

Drop expansion on the hilar appendix of spores in the ESEM resembles the process that creates the Buller's drop in the seconds before spore discharge from mushroom gills ( Fig 3). The regrowth of this discrete drop is only visible in spores that are oriented with the hilar appendix pointing away from the surface of the stub on which the spores are deposited. Drop formation in the ESEM on the adjacent spore surface is more common ( Fig 4). This may be explained by the coalescence of the two droplets on the spore at the moment of spore discharge ( Fig 1). When this occurs, mannitol secreted on the hilar appendix and adjacent surface is mixed in the combined volume of water ( Fig 1). When water evaporates from the spore surface, the mannitol is spread over a larger portion of the spore surface. This would explain why the water that condenses on the spores grows as a single drop rather than two separate drops. Because the spores in the ESEM do not move, water vapor continues to condense on their surfaces creating drops that are significantly larger than those that form during the discharge process.

Significance in clouds

The dispersal of vast numbers of hygroscopic basidiospores into the atmosphere above forests may have a significant role in the condensation of water in clouds and the formation of raindrops. Previous studies have suggested that fungal spores may operate as ice-nucleating agents at low temperatures [ 16]. We propose a different role for basidiospores in the dynamics of cloud formation and rainfall in the present study. Supersaturation is a transient and dynamic state in clouds in which the moisture levels exceed a RH of 100%. Typical levels of supersaturation in clouds boost RH values to 102% [ 17] and rarely exceeds 110% RH [ 18]. Droplet formation on spores in the ESEM observed at RH values ranging from 100% to 102% RH match the environmental conditions found in clouds.

Coarse aerosolized particles with a diameter exceeding 2 μm play an important role within clouds as seeds for the formation of water droplets. When water condenses on the surface of these particles, they operate as giant cloud condensation nuclei (GCCN) that form larger droplets by coalescing with smaller droplets and merging with one another [ 19]. Raindrop formation occurs via coalescence of water droplets with GCCN rather than sustained condensation of water vapor [ 20]. Hygroscopic basidiospores, which are classed as large aerosol particles, may be particularly effective as GCCN. The size of the droplets observed in the ESEM suggest that mushroom spores act as giant cloud condensation nuclei, aiding the coalescence of smaller droplets to form precipitation-sized drops ( Fig 8). Non-ballistosporic basidiospores may act also as nuclei for water condensation in clouds, but they operate in a similar fashion to particulates of non-biological origin and do not stimulate active droplet formation like ballistospores.

(A-C) Condensation of water on the spore surface associated with spore discharge. Process of drop formation is driven by the presence of hygroscopic sugars on the spore surface in the two positions shown in gray in A. (D, E) Water evaporates from the surface of the airborne spore. (F) Condensation of water on the spore surface resumes under conditions of high atmospheric relative humidity. (G) Larger droplets of water formed by merger of spores carrying smaller droplets.

Wider environmental importance

Mushroom expansion is a hydraulic process that involves the osmotic inflation of tissues that expose gills and other configurations of spore-producing tissues. Mushroom-forming basidiomycetes are vital to the productivity of many forest ecosystems supported by heavy rainfall [ 21]. The behavior of spores revealed in this study suggests that a positive feedback mechanism may operate in which fungi whose growth is stimulated by rain, disperse massive quantities of spores that enhance precipitation. This hypothetical process is a consequence of a mechanism of spore discharge that occurs in 16,000 described species of mushrooms as well as basidiomycete yeasts and rust fungi that infect plants. There is no adaptive significance to the putative effect of spores on cloud formation. It is a consequence of the dispersal mechanism that happens to benefit the fungus beyond its effectiveness at distributing spores. If changes in climate reduce rainfall in tropical ecosystems, the resulting inhibition of fungal growth and spore release may exacerbate the frequency of droughts through this unexpected feedback loop.

Acknowledgments

The authors thank the staff of the ESEM Laboratory in the Department of Geology, University of Akron, for assistance with the experiments.

Author Contributions

Conceived and designed the experiments: MOH MWFF NPM. Performed the experiments: MOH. Analyzed the data: MOH MWFF NPM. Contributed reagents/materials/analysis tools: MWFF. Wrote the paper: MOH NPM.

References

2. Money NP. Mushroom. Oxford University Press; 2011.

7. Pringle A, Patek SN, Fischer M, Stolze J, Money NP. The captured launch of a ballistospore. Mycologia 2005;97: 866-871. pmid:16457355

8. Pöschl U, Martin ST, Sinha B, Chen Q, Gunthe SS, Huffman JA, et al. Rainforest aerosols as biogenic nuceli of clouds and precipitation in the Amazon. Science 2010;329: 1513-1516. pmid:20847268

14. Lamb D, Verlinde J. Physics and chemistry of clouds. Cambridge University Press; 2011.

15. Fischer MW, Stolze-Rybczynski JL, Cui Y, Money NP. How far and how fast can mushroom spores fly? Physical limits on ballistospore size and discharge distance in the Basidiomycota. Fungal Biol. 2010;114: 669-675. pmid:20835365

17. Seinfeld JH, Pandis SN. Atmospheric chemistry and physics: from air pollution to climate change. John Wiley; 2012.

20. Cotton WR, Yuter S. (2009). Principles of cloud and precipitation formation. In: Levin Z, Cotton WR, editors. Aerosol pollution impact on precipitation. Netherlands: Springer; 2009. pp. 13-43.

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Mushrooms as Rainmakers: How Spores Act as Nuclei for Raindrops

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Millions of tons of fungal spores are dispersed in the atmosphere every year. These living cells, along with plant spores and pollen grains, may act as nuclei for condensation of water in clouds. Basidiospores released by mushrooms form a significant proportion of these aerosols, particularly above tropical forests.

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What if, rather than mere props in the background of our lives, trees embody the history of all life on Earth?

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Place yourself on the West Coast of the South Island of New Zealand, near the Franz Josef Glacier. Officially, this forest is a temperate podocarp-hardwood rainforest, but these dry words belie the rich diversity of plant life around, encompassing every imaginable shade of green, brown and grey. They also do an injustice to the experience of standing dwarfed by the soaring trunks of the 400-year-old rimu trees draped in moss, with their beautifully drooping branches of tiny deep-green needles like a million cascading green waterfalls. And then imagine standing in this forest during an all-too-common torrential rainstorm blown off the nearby Tasman Sea; the literal waterfall from the sky mirrors the vegetative waterfall, and your senses are overwhelmed by the power of water and vegetal life. To stand in this forest is to understand one of the most basic facts about life on Earth: trees are by far the most significant beings on this planet.

Every schoolchild learns some of these seemingly straightforward facts - trees provide us with sustenance, and their photosynthetic activity, along with that of phytoplankton, creates an atmosphere that enables our survival. Without them, the Earth would be uninhabitable - and with their rising rates of death and extinction, the Earth might indeed become uninhabitable soon. Trees also populate our imagination, and many schoolchildren become familiar with trees through fairytales where the forest looms large, or through Aboriginal cultures, where trees are regarded as community members. We are also becoming increasingly aware of the extent to which they improve our mental wellbeing.

And yet, despite the biological and cultural significance of trees, we rarely notice them - a phenomenon that scientists have described as 'plant blindness'. This might have to do with the fact that they are immobile, or that they don't appear to pose danger. It might also have to do with their marginalisation in Western thought - a fact that the philosopher Michael Marder in his book The Philosopher's Plant (2014) attributes to Western philosophy's self-understanding. Since Socrates, the primary aim of philosophising has been to save the soul from its bodily corruption. Yet, trees (and plants more generally) symbolise the ongoing transformations, and thus corruptions and degradations, associated with the living body: from growth to decay and eventually death. In other words, before us and in plain sight, they present precisely that from which we want to distance ourselves.

Even when philosophers turn their attention to understanding life processes, they largely ignore trees or relegate them to the periphery. In his Critique of the Power of Judgment (1790), Immanuel Kant regards trees as 'self-organising' but not as 'alive' - because they lack an essential characteristic of life: desire (which animals possess). In The Phenomenon of Life (1966), Hans Jonas argues that plants don't possess a 'world' because they can't be contrasted with their environments. Thus, while the animal-environment relation is one between a sensing, directed subject and a 'world', the plant-environment relation is between a nonsubject and nonobjects, or as Jonas puts it: 'consists of adjacent matter and impinging forces'.

Kant and Jonas are no exceptions, but exemplify the rule: theoretical accounts of life, of the organism and its relation to the environment, rarely consider plants. This might be because, like Kant, we regard them as somehow lacking, or like Jonas, we identify them with the environment. After all, trees, like all plants, are rooted in the soil at a single location, making them the basic building blocks of an 'environment'. They provide habitats, nourishment and shade for nonhuman and human animals, as well as a multiplicity of microorganisms and other plants. This seems to imply that trees are the 'props' of the animal stage - objects that are largely passive in contrast with the active work of humans and other animals.

The identification of tree with environment can, under some definitions, mean that trees are not, strictly speaking, 'organisms'. This is because a key feature of organisms is their distinction from their environments (ie, the fact that they maintain themselves in the face of changes to their environments). Thus, although today we would not claim with Kant that trees are not 'alive', certain definitions of organisms logically imply that trees fundamentally differ from all other living beings.

But is it really the case that trees are simply the 'stage setting' for animal activity? In terms of numbers alone, this cannot be true, and a more apt metaphor would be that animals are the decorations or props on the Earth's complex vegetal life system: more than 80 per cent of live carbon on the Earth resides in plants. Furthermore, alongside humans, trees are the dominant drivers of terrestrial biogeochemical cycles in the Anthropocene, influencing the Earth's environment in ways that no (nonhuman) animal can. And, as recent research has shown, trees communicate to influence and transform their environments in ways that challenge our common understanding of both trees and environments.

This recent research, which has inspired a number of literary and artistic works focused on trees, prompts us to pose the following questions: if trees are not simply the environment, but active participants within it, then what exactly is the tree-environment relationship, and what can trees teach us about the very idea of an 'environment'? What might we be able to learn from trees about the ways in which living beings relate to their environments more generally, and how might the tree-environment relation lead us to think about our own environmental connections and futures in new and productive ways?

Trees are the longest-living life form we know, and manifest their temporal and geographic histories within their very bodies. In both form and function, trees tell the stories of their individual past, which is intimately connected to the history of their microenvironments as well as that of the planet. This distinctive and intimate relation between trees and their temporal and geographic histories is what we call the 'embodied history of trees'.

Tree rings are the best-known example of an embodied history, and offer a vivid instantiation of the way in which living beings 'carry' their past into the present. Wood formed during the spring growth-flush has large, thin-walled cells that are paler in colour than the smaller, thicker-walled cells produced in late summer, resulting in a repeating pattern of concentric rings. We know that trees grow fastest when they have ample water and sunlight, and when temperatures are warmest (at least in the northern hemisphere temperate region where most of the original work was done), so tree-ring width has been widely used to reconstruct past climates.

But tree rings record more than just growth rate: the chemical composition of wood contains a chronological archive of the environment and the tree's response to that environment. The increasing atmospheric carbon-dioxide concentration over the past 100 years is recorded in the stable carbon isotope composition of tree rings, because the carbon dioxide produced during fossil-fuel burning has fewer of the naturally occurring, but rare, carbon atoms with 13 neutrons. This means that trees have an embodied record of both the industrial revolution, and our current stubborn dependency on fossil fuels. Trees, in other words, might be best able to tell us exactly when climate change began to occur, and determine the most viable starting point of our current geological era, the Anthropocene.

In an inspired study, researchers took a core from the stem of a Sitka spruce ( Picea sitchensis) planted on Campbell Island - one of the most remote in the Southern Ocean - and found a peak in the radiocarbon composition within the annual growth ring for 1965. The peak reflects the fixation of atmospheric radiocarbon released during nuclear testing in the 1950s and '60s. This, the scientists suggest, marks the beginning of the Anthropocene.

The tree story of the human transformation of biogeochemical cycles has overlain upon it the story of the tree's own response to environmental stresses. We can tell the tree's weekly story if annual rings are divided sequentially into thin slices and analysed separately. Hot and dry summers are recorded as narrow growth-rings with sharp peaks in carbon-13 and oxygen-18 composition, while mild, sunny summers with high rainfall result in broad-flat peaks and wide growth-rings. In this way, the embodied history of trees offers a window into the alien lives of plants - if we translate their stories through science.

A human equivalent to tree plasticity would be certain people growing webbed feet because they swim a lot

Of course, animals have embodied histories, too. The bones and tooth enamel in mammals are known to record a range of environmental and physiological signals during the time that they formed. For example, the radiocarbon concentration of femoral cortical bone (dense regions of thigh bones) has been used to determine the years during which terrestrial mammals such as brown bear and sika deer were in their adolescence, and the Irish potato famine is recorded in the stable carbon and nitrogen isotope composition of human teeth and bones. But these embodied histories are an integrative record, not chronological records like tree rings. The most widely used chronological animal embodied histories are the ear bones of fish. These tiny bones, called otoliths, grow at different rates over a year, resulting in annual rings just like tree rings, and their chemical composition can reveal details of fish migratory patterns and diet.

Thus, while all living beings carry their past with them into their present and future selves, trees embody their history in a way that is far more explicit and with greater detail and visibility than any other living being. The history of any particular tree is not hidden in an interior part, nor is it found in only one of its parts. As such, trees call attention to the historicity of life, demanding that we think of life not as static and machine-like, but as dynamic, context-sensitive, and plastic.

Trees are not only embodied recorders of their history, but also shapeshifters, whose structure transforms in relation to their environment. Put simply, trees express their context in their physical form. Trees of the same species can look significantly different depending on their growth environment and, even within an individual tree, the leaves at the shady bottom of the canopy are anatomically different (larger and thinner) from those at the top (smaller and thicker). When densely planted, trees grow long, straight trunks and small canopies, but when planted in a grass field, they grow shorter stems and broad crowns. The crown of a solitary oak spreads out in all directions, eventually achieving a dome shape, while an oak growing in a forest develops a small crown, and its growth is patterned on the growth of surrounding trees. Or think of a bonsai tree in contrast to its full-size sibling. Trees are so adaptive to their surroundings that a human equivalent to tree plasticity would be certain people growing large webbed feet (like diving flippers) simply because they swim a lot.

The intimate relationship between tree and context is expressed in every one of the tree's parts, from the root to the crown. This is clear from the fact that two trees of the same species growing in different soils develop very differently, and not only in the later stages, but from the start. In humus-poor earth, the root of an oak is short, with far less branching than the same species in humus-rich soil. The tree senses its context from the beginning and develops in dialogue with it. Every one of its parts is, ultimately, telling the story of its distinctive context.

Trees are not merely receptive or passive in relation to their environment, they are also environmental engineers. Large trees exert a strong influence over their immediate environment, and urban trees alter the environment in ways that have clear benefits to humans. They provide what has been (perhaps problematically) described as 'environmental ecosystem services'. We are all familiar with the shading and cooling effects of urban trees, but less well-known are the effects of large urban trees on aerosol pollution reduction, slope stabilisation and regulation of water flow within urban catchments. These 'ecosystem services' increase the desirability of suburban properties (think of agent descriptions of a 'leafy suburb'), leading to broad correlations in the US between the extent of urban tree-canopy cover and median household income.

In forests, some tree species alter their environment in such radical ways that they determine the species composition around them. The giant kauri ( Agathis australis), a species endemic to the northern regions of New Zealand, is one of the most sophisticated environmental engineers. Its fallen leaves create thick layers of humus on the forest floor. Over time, the highly acidic leachate from the humus can wash virtually all nutrients from the soil, resulting in a pale lens of low-nutrient, acidic soil within the root zone called a cup podzol. The plant communities growing on these highly modified soils are distinctly different to neighbouring communities.

Trees are also environmental engineers at the very largest scale. In the vast forests of the Amazon, trees drive the hydrological cycle by lifting soil water into their canopies where it evaporates and is released to the atmosphere as vapour, a process called transpiration. Hence, much of the water that falls as rain in the Amazon comes from transpiration ( estimated to be 30 to 50 per cent), perhaps cycling a number of times from soil to atmosphere through trees before leaving the continent mostly via the massive river system. Furthermore, recent research in the southern Amazon has revealed that transpiration during the late dry season brings forward the dry-to-wet transition by two to three months. The dry season has been increasingly delayed in the southern Amazon in recent decades, prompting suggestions that continued clearing of land for agriculture and changes in fire regimes might trigger a collapse of the rainforest and the development of savannah.

The fact that trees are the material manifestation of their temporal and geographic history reveals a deep and inextricable relation between the tree and its environment. It demonstrates that any particular tree expresses its environment, and its environment is, in turn, an expression of the tree. This intimate relation between tree and environment might be most aptly expressed, to borrow from Marder's book Plant-Thinking (2013), in terms of synecdoche (a part that signifies or expresses a whole): trees are a synecdoche for the environment.

The environment is an expression of the tree just as the tree is an expression of its environment

For Marder, the synecdoche is between plants and nature, where the plant's activity of generation and development is representative of the characteristics that we associate with nature as a whole. The plant, then, is the part that represents the whole (nature). Our view is that there is a synecdoche between tree and environment. This is because the tree's environment is literally inscribed on every part of the tree and on the tree as a whole. As a synecdoche for the environment, the tree stands for, or represents, its environment in each of its parts.

But the inverse is also true. The environment is an expression of the tree just as much as the tree is an expression of its environment. This is clear in the example of soil, which undergoes significant and lasting evolutionary changes as a direct result of the actions of a tree. Or, as the ecologists Richard Levins and Richard Lewontin put it in The Dialectical Biologist (1985): 'the seedling is the "environment" of the soil'. The (seed) environment is, in other words, an expression of the seed.

However, trees do more than simply influence or transform their environment: they create it. By determining which aspects of their surroundings are relevant for their development, trees bring about their own microenvironment. And in so doing, they offer us a way to distinguish mere surroundings from environment. An environment - in contrast to surroundings - entails an ongoing, productive relating over time in a particular place. In other words, the very notion of 'environment' depends on and cannot be separated from those who actively participate in the environment, and trees are prime actors in this regard. To recall an example offered above, the Amazon is an expression of the trees that both make it up and regulate its hydrological cycles.

What we find, then, is a relation of reciprocal causation and dependency between tree and environment. Trees express their environments in their form and activity; and the environment is expressed (realised) in and through the trees. The one does not precede and effect the other. They emerge simultaneously and in relation to one another.

The tree-environment relationship appears to mirror our understanding of a living organism, in contrast to machines. An organism is composed of parts that are mutually causing and forming one another, such that the one (eg, the lungs) cannot exist without the other (eg, the heart), and the function of the one depends on the function of the other. The same kind of mutual dependence obtains between tree and environment - between a living being and its (in part nonliving, physical) context.

To claim that tree and environment are engaged in a process of reciprocal causation, such that the one cannot exist without the other, is to challenge the view that it is only living beings or organisms that are composed of mutually forming and interdependent parts (eg, heart and lungs). In other words, the tree-environment relation implies that what has long been recognised as the defining feature of individual organisms extends beyond them and can be found in the interactions between living (organism) and nonliving (environment).

But first, we must consider the sense in which the tree itself is an organism. Living beings or organisms have been traditionally designated as self-organising, a characteristic that is often associated with autonomy. This is because organisms are recognised as capable of maintaining themselves (through growth, healing, nourishment, and reproduction) in opposition to environmental influences (even if they also rely on their environments).

Trees appear to undermine this understanding of organisms - and it might be for this reason, as we mentioned above, that they have been largely ignored. For one, trees do not stand in contrast to their environments, but sense their environments and adjust their form accordingly. Furthermore, they alter their environments to suit their form. Both of these facts imply that the environment is in some significant sense a member or a part of the tree. As such, it is difficult to determine where 'organism' ends and 'environment' begins. In what sense, then, can a tree be designated as an organism?

There appear to be lifelike capacities or qualities in what is, strictly speaking, not alive

A first answer might be gained from considering the fact that the various parts of any tree express a unified response to the tree's environment. No part acts haphazardly or in contrast to the other parts. This is vividly captured in the example of the oaks offered above. In the humus-poor earth, the root, just as much as any other part of the tree, expresses its environment. The tree does not begin with the aspiration of becoming a very large oak and adapt only afterwards. Rather, from the very beginning the tree senses its context and emerges in dialogue with it. This unity or coherence in the tree's response is possible only if the various parts of the tree emerge interdependently. The parts, in other words, cannot exist independently of one another or pre-exist the whole, but actively form and inform one another, such that the one cannot exist without the other. In this sense, the tree is an organism - an organised unity or whole.

However, precisely because it is in response to its environment that a tree emerges as a whole, it cannot be understood in contrast to its environment. Rather, the tree emerges as a whole only in its environment. Its unity is not isolated from its environment, which means that its structure as an organism is not 'autonomous' and 'self-generative', but dialogical, responsive and fluid, both internally and in relation to the environment.

The consequences of this view challenge us to think carefully about the relation between organism and environment, and about the line we usually draw between life and nonlife. For if we begin to conceive of the environment as an essential component of the tree organism, then we must conclude that the physical environment is neither something external to the tree, nor something inert or dead, in opposition to the living character of the tree. Rather, we must begin to recognise that the processes we usually identify with life are also present in the relations between life and nonlife. In other words, there appear to be lifelike capacities or qualities in what is, strictly speaking, not alive in the sense that it does not (at least not explicitly) grow, heal, nourish and propagate. The tree-environment relation thus leads us to think about environments differently - not as assemblages of inert objects, or as meaningful only in relation to particular (individual) organisms, but as members or parts of organisms, and thus as 'alive' in some sense, even if they don't appear to be growing, healing, nourishing and propagating in the manner of individual organisms.

The embodied history of trees and the tree-environment synecdoche offer important insights that require us to think carefully about our understanding of 'nature' and our self-understanding.

In the first place, the tree-environment synecdoche offers a path for thinking about nature in more fluid and capacious ways, in ways that might be better able to address environmental sustainability and multispecies justice. In the era of the Anthropocene, new ontologies of nature are needed: ones that are able to accommodate and take account not only of individual species and their competing interests, but also of environments, and relations that undergird and enable the emergence of species. The tree-environment relation allows us to see beyond individual autonomy without losing integrity, and thereby takes us a step further toward understanding the complex and varied demands of sustainability and justice in the Anthropocene.

It also challenges us - especially if we begin to conceive of trees not as passive elements in an environment, but as active members, transforming, influencing and creating an environment. It challenges us, in other words, to think again, and to think differently, about what we mean by subjectivity and agency and whether trees can be described as agents with interests, in a meaningful and significant way. The liberal-democratic conception of a rights-bearing subject implies, as the political philosopher Martha Nussbaum puts it, that the subject be 'able to move freely, from place to place' and possess 'bodily boundaries'. On this account, trees can never be regarded as subjects with rights.

This leads to a second challenge: the challenge not only to think differently about trees but also about ourselves. What if we should not regard ourselves as agents in the way Nussbaum enumerates? What if, in the age of the Anthropocene, there is something problematic about regarding mobility as an essential feature of subjectivity and agency?

After all, as mobile as we might think of ourselves, we are ultimately bound to the planet. In fact, it is the forgetting of our boundedness, of our dependence on healthy soil, clean water and air, forests, swamps and deserts, that has brought us to the suicidal situation in which we find ourselves. Remembering our boundedness, remembering our tree-like character, might serve an important step in transforming the way we think about ourselves, our place and our environmental future.

What might we learn and how might our behaviour change if we discarded the model of agency founded on mobility, autonomy and sovereignty, and adopted the model that trees offer us: rootedness, relationality, dialogue and responsiveness?

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What can an embodied history of trees teach us about life? - Dalia Nassar & Margaret M Barbour | Aeon Essays

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Place yourself on the West Coast of the South Island of New Zealand, near the Franz Josef Glacier. Officially, this forest is a temperate podocarp-hardwood rainforest, but these dry words belie the rich diversity of plant life around, encompassing every imaginable shade of green, brown and grey.

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New study shows vegetation controls the future of the water cycle

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New study shows vegetation controls the future of the water cycle

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By disentangling the vegetation response from the atmospheric response, researchers were able to quantify it and found that the vegetation actually is the dominant factor explaining future water stress.

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View from Guanica Biosphere Preserve, Puerto Rico. Credit: Kevin Krajick/Earth Institute

Predicting how increasing atmospheric CO2 will affect the hydrologic cycle, from extreme weather forecasts to long-term projections on agriculture and water resources, is critical both to daily life and to the future of the planet. It is commonly thought that hydrologic change is driven by precipitation and radiation changes caused by climate change, and that as the land surface adjusts, rising temperatures and lower precipitation will make the planet drier.

Columbia Engineering researchers have found that, to the contrary, vegetation plays a dominant role in Earth's water cycle and that plants will regulate and dominate the increasing stress placed on continental water resources in the future. The study, led by Pierre Gentine, associate professor of earth and environmental engineering at Columbia Engineering and at the Earth Institute, is published today in the Proceedings of the National Academy of Sciences.

"Our finding that vegetation plays a key role future in terrestrial hydrologic response and water stress is of utmost importance to properly predict future dryness and water resources," says Gentine, whose research focuses on the relationship between hydrology and atmospheric science, land/atmosphere interaction, and its impact on climate change. "This could be a real game-changer for understanding changes in continental water stress going into the future."

Gentine's team is the first to isolate the response of vegetation from the global warming total complex response, which includes such variables for the water cycle as evapotranspiration (the water evaporated from the surface, both from plants and bare soil) soil moisture, and runoff. By disentangling the vegetation response to the global rise of CO2 from the atmospheric (greenhouse gas) response, they were able to quantify it and found that the vegetation actually is the dominant factor explaining future water stress.

"Plants are really the thermostat of the world," says Léo Lemordant, Gentine's PhD student and lead author of the paper. "They're at the center of the water, energy, and carbon cycles. As they take up carbon from the atmosphere to thrive, they release water that they take from the soils. Doing that, they also cool off the surface, controlling the temperature that we all feel. Now we know that mainly plants?not simply precipitation or temperature?will tell us whether we will live a drier or wetter world."

For the study, Gentine and Lemordant took Earth system models with decoupled surface (vegetation physiology) and atmospheric (radiative) CO2 responses and used a multi-model statistical analysis from CMIP5, the most current set of coordinated climate model experiments set up as an international cooperation project for the International Panel on Climate Change. They used three runs: a control run with CO2 at the leaf level and in the atmosphere, a run where only the vegetation responds to a rise in CO2, and a run where only the atmosphere responds to the CO2 increase.

Their results showed that changes in key water-stress variables are strongly modified by vegetation physiological effects in response to increased CO2 at the leaf level, illustrating how deeply the physiological effects due to increasing atmospheric CO2 impact the water cycle. The CO2 physiological response has a dominant role in evapotranspiration and has a major effect on long-term runoff and soil moisture compared to radiative or precipitation changes due to increased atmospheric CO2.

This study highlights the key role of vegetation in controlling future terrestrial hydrologic response and emphasizes that the continental carbon and water cycles are intimately coupled over land and must be studied as an interconnected system. It also emphasizes that hydrologists should collaborate with ecologists and climate scientists to better predict future water resources.

"The biosphere physiological effects and related biosphere-atmosphere interactions are key to predicting future continental water stress as represented by evapotranspiration, long-term runoff, soil moisture, or leaf area index," Gentine says. "In turn, vegetation water stress largely regulates land carbon uptake, further emphasizing how tightly the future carbon and water cycles are coupled so that they cannot be evaluated in isolation."

Gentine and Lemordant plan to further untangle the various physiological effects. "The vegetation response is itself indeed complex," Gentine says, "and we want to decompose the impact of biomass growth vs. stomatal response. There are also implications for extreme heatwave events we are currently working on."

"This work highlights an important need to further study how plants will respond to rising atmospheric carbon dioxide," says James Randerson, professor of earth system science, University of California, Irvine, who was not involved with the study. "Plants can have a big effect on the climate of land, and we need to better understand the ways that they will respond to carbon dioxide, warming, and other forms of global change."

More information: Léo Lemordant el al., "Critical impact of vegetation physiology on the continental hydrologic cycle in response to increasing CO2," PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1720712115

Journal information: Proceedings of the National Academy of Sciences

Provided by Columbia University School of Engineering and Applied Science

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New study shows vegetation controls the future of the water cycle

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Predicting how increasing atmospheric CO2 will affect the hydrologic cycle, from extreme weather forecasts to long-term projections on agriculture and water resources, is critical both to daily life and to the future of the planet.

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The soil is alive and it is also a carbon sink, storing carbon as part of the carbon cycle. Without the living soil, there would be no other life on Earth.

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The Soil Solution to Climate Change Film

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Bacteria Contradict Darwin: Survival of the Friendliest

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Bacteria Contradict Darwin: Survival of the Friendliest

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New microbial research at the University of Copenhagen suggests that 'survival of the friendliest' outweighs 'survival of the fittest' for groups of bacteria

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Credit: University of Copenhagen

New microbial research at the University of Copenhagen suggests that 'survival of the friendliest' outweighs 'survival of the fittest' for groups of bacteria. Bacteria make space for one another and sacrifice properties if it benefits the bacterial community as a whole. The discovery is a major step towards understanding complex bacteria interactions and the development of new treatment models for a wide range of human diseases and new green technologies.

New microbial research at the Department of Biology reveals that bacteria would rather unite against external threats, such as antibiotics, rather than fight against each other. The report has just been published in the scientific publication ISME Journal. For a number of years the researchers have studied how combinations of bacteria behave together when in a confined area. After investigating many thousands of combinations it has become clear that bacteria cooperate to survive and that these results contradict what Darwin said in his theories of evolution.

"In the classic Darwinian mindset, competition is the name of the game. The best suited survive and outcompete those less well suited. However, when it comes to microorganisms like bacteria, our findings reveal the most cooperative ones survive," explains Department of Biology microbiologist, Professor Søren Johannes Sørensen.
Social bacteria work shoulder to shoulder
By isolating bacteria from a small corn husk (where they were forced to "fight" for space) the scientists were able to investigate the degree to which bacteria compete or cooperate to survive. The bacterial strains were selected based upon their ability to grow together. Researchers measured bacterial biofilm, a slimy protective layer that shields bacteria against external threats such as antibiotics or predators. When bacteria are healthy, they produce more biofilm and become stronger and more resilient.

Time after time, the researchers observed the same result: Instead of the strongest outcompeting the others in biofilm production, space was allowed to the weakest, allowing the weak to grow much better than they would have on their own. At the same time the researchers could see that the bacteria split up laborious tasks by shutting down unnecessary mechanisms and sharing them with their neighbors.

"It may well be that Henry Ford thought that he had found something brilliant when he introduced the assembly line and worker specialization, but bacteria have been taking advantage of this strategy for a billion years," says Søren Johannes Sørensen referring to the oldest known bacterial fossils with biofilm. He adds:

"Our new study demonstrates that bacteria organize themselves in a structured way, distribute work and even to help each other. This means that we can find out which bacteria cooperate, and possibly, which ones depend on each another, by looking at who sits next to who."
Understanding invisible bacterial synergy
The researchers also investigated what properties bacteria had when they were alone versus when they were with other bacteria. Humans often discuss the work place or group synergy, and how people inspire each other. Bacteria take this one step further when they survive in small communities.

"Bacteria take our understanding of group synergy and inspiration to a completely different level. They induce attributes in their neighbors that would otherwise remain dormant. In this way groups of bacteria can express properties that aren't possible when they are alone.

When they are together totally new features can suddenly emerge," Søren Johannes Sørensen explains.

Understanding how bacteria interact in groups has the potential to create a whole new area in biotechnology that traditionally strives to exploit single, isolated strains, one at a time.

"Bio-based society is currently touted as a solution to model many of the challenges that our societies face. However, the vast majority of today's biotech is based on single organisms. This is in stark contrast to what happens in nature, where all processes are managed by cooperative consortia of organisms. We must learn from nature and introduce solutions to tap the huge potential of biotechnology in the future," according to Søren Johannes Sørensen.

More information: Wenzheng Liu et al, Deciphering links between bacterial interactions and spatial organization in multispecies biofilms, The ISME Journal (2019). DOI: 10.1038/s41396-019-0494-9

Journal information: ISME Journal

Provided by University of Copenhagen

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Bacteria contradict Darwin: Survival of the friendliest

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New microbial research at the University of Copenhagen suggests that 'survival of the friendliest' outweighs 'survival of the fittest' for groups of bacteria. Bacteria make space for one another and sacrifice properties if it benefits the bacterial community as a whole.

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Excerpted from Robert Macfarlane's recently published book, Underland: A Deep Time Journey, “The Understory” is an examination of the life beneath the forest floor.

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Excerpted from his recently published book, Underland: A Deep Time Journey, "The Understory" is an examination of the life beneath the forest floor. Encountering the depth and complexity of communication that happens underground, Robert returns to the entangled mutualism at the root of language.

Occasionally-once or twice in a lifetime if you are lucky-you encounter an idea so powerful in its implications that it unsettles the ground you walk on.

The first time I heard anyone speak of the "wood wide web," more than a decade ago now, I was trying not to cry. A beloved friend was dying too young and too quickly. I had gone to see him for what I took to be the last time. He was tired by pain and drugs. We sat together, talked. My friend was a woodsman. Trees grew through his life and thought. His grandfather's surname was Wood, he lived in a timber-framed house that he had built himself, and he had planted thousands of trees by hand over the years. "I have sap in my veins," he wrote once.

That day I read aloud a poem that was important to us both, "Birches" by Robert Frost, in which climbing the snow-white trunks of birches becomes both a readying for death and a declaration of life. Then he told me about new research he had recently read concerning the interrelations of trees: how, when one of their number was sickening or under stress, they could share nutrients by means of an underground system that conjoined their roots beneath the soil, thereby sometimes nursing the sick tree back to health. It was a measure of my friend's generosity of spirit that-so close to death himself-he could speak unjealously of this phenomenon of healing. He did not have the strength then to tell me the details of how this belowground sharing operated-how tree might invisibly reach out to tree within the soil. But I could not forget the image of that mysterious buried network, joining single trees into forest communities. It was planted in my mind, and there took root. Over the years I would encounter other mentions of the same extraordinary idea, and gradually these isolated fragments began to connect together into something like understanding.

In the early 1990s a young Canadian forest ecologist called Suzanne Simard, studying the understory of logged temperate forests in northwest British Columbia, observed a curious correlation. When paper birch saplings were weeded out from clear-cut and reseeded plantations, their disappearance coincided with first the deterioration and then premature deaths of the planted Douglas fir saplings among which they grew.

Foresters had long assumed that such weeding was necessary to prevent the young birches (the "weeds") depriving the young firs (the "crop") of valuable soil resources. But Simard began to wonder whether this simple model of competition was correct. It seemed to her plausible that the paper birches were somehow helping rather than hindering the firs: when they were removed, the health of the firs suffered. If this interspecies aid-giving did exist between trees, though, what was its nature-and how could individual trees extend help to one another across the spaces of the forest?

Simard decided to investigate the puzzle. Her first task was to establish some kind of structural basis for possible connections between the trees. Using microscopic and genetic tools, she and her colleagues peeled back the forest floor and peered below the understory, into the "black box" of the soil-a notoriously challenging realm of study for biologists. What they saw down there were the pale, superfine threads known as "hyphae" that fungi send out through the soil. These hyphae interconnected to create a network of astonishing complexity and extent. A teaspoonful of soil could hold up to seven miles of hyphae.

For centuries, fungi had generally been considered harmful to plants: parasites that caused disease and dysfunction. As Simard began her research, however, it was increasingly thought that certain kinds of common fungi might exist in subtle mutualism with plants. The hyphae of these so-called "mycorrhizal" fungi were understood not only to infiltrate the soil, but also to weave into the tips of plant roots at a cellular level-thereby creating an interface through which molecular transmission might occur. By means of this weaving, too, the roots of individual plants or trees were joined to one another by a magnificently intricate subterranean system.

Simard's inquiries confirmed that beneath her forest floor there did indeed exist what she called an "underground social network," a "bustling community of mycorrhizal fungal species" that linked sapling to sapling. She also discovered that the hyphae made connections between species: joining not only paper birch to paper birch and Douglas fir to Douglas fir, but also fir to birch and far beyond-forming a non-hierarchical network between numerous kinds of plants.

Simard had established a structure of connection between the saplings. But the hyphae provided only the means of mutualism. Its existence did not explain why the fir saplings faltered when the birch saplings were weeded out, or details as to what-if anything-might be transmitted via this collaborative system. So Simard and her team devised an experiment that could let them track possible biochemical movements along this invisible buried lattice. They decided to inject fir trees with radioactive carbon isotopes. Using mass spectrometers and scintillation counters, they were then able to track the flow of carbon isotopes from tree to tree.

I could not forget the image of that mysterious buried network, joining single trees into forest communities.

What this tracking revealed was astonishing. The carbon isotopes did not stay confined to the individual trees into which they were injected. Instead, they moved down the trees' vascular systems to their root tips, where they passed into the fungal hyphae that wove with those tips. Once in the hyphae they traveled along the network to the root tips of another tree, where they entered the vascular system of that new tree. Along the way, the fungi drew off and metabolized some of the photosynthesized resources that were moving along their hyphae; this was their benefit from the mutualism.

Here was proof that trees could move resources around between one another using the mycorrhizal network. The isotope tracking also demonstrated the unexpected intricacy of the interrelations. In a research plot thirty meters square, every single tree was connected to the fungal system, and some trees-the oldest-were connected to as many as forty-seven others. The results also solved the puzzle of the fir-birch mutualism: the Douglas firs were receiving more photosynthetic carbon from paper birches than they were transmitting. When paper birches were weeded out, the nutrient intake of the fir saplings was thus-counterintuitively-reduced rather than increased, and so the firs weakened and died.

The fungi and the trees had "forged their duality into a oneness, thereby making a forest," wrote Simard in a bold summary of her findings. Instead of seeing trees as individual agents competing for resources, she proposed the forest as a "cooperative system," in which trees "talk" to one another, producing a collaborative intelligence she described as "forest wisdom." Some older trees even "nurture" smaller trees that they recognize as their "kin," acting as "mothers." Seen in the light of Simard's research, the whole vision of a forest ecology shimmered and shifted-from a fierce free market to something more like a community with a socialist system of resource redistribution.

Simard's first major paper on the subject was published in Nature in 1997, and it was from there that the subterranean network of tree-fungus mutualism gained its durable nickname of "the wood wide web." Her Nature paper was a groundbreaking publication, the implications of which were so significant that an entire research field subsequently formed to pursue them. Since then the scientific study of belowground ecology has boomed. New technologies of detection and mapping have illuminated fresh details of this "social network" of trees and plants. "The wood wide web has been mapped, traced, monitored and coaxed," as Simard puts it, "to reveal the beautiful structures and finely adapted languages of the forest network."

And among this new generation of the forest's linguists and mappers is a young plant scientist called Merlin Sheldrake. Truly, that is his name.

Merlin and I stand side by side in a beech coppice-the biggest I have ever seen, let alone entered. The stool is ten yards from one end to another, the tree perhaps 400 or 500 years old.

"I'd guess this hasn't been coppiced for at least half a century," I say to Merlin.

Coppice shoots have grown, unlopped, into upright trunks, raying up around the edge of the coppice's base and leaving a space in the center easily big enough to hold us both. We stay there for a while, enjoying being inside this ancient tree, looking out at Epping Forest from between the gray-barked bars of our cage.

Two of the beech's lower limbs have melted into one another, their bark conjoining into a single continuous skin, their vascular systems growing and uniting. Living wood, left long enough, behaves as a slow-moving fluid. Like glacial ice-like the halite I had seen in Boulby, like the calcite I had seen in the Mendips, like stained glass in medieval churches which, over centuries, gradually thickens out at the base of each pane-living wood flows, given time. "I've heard this called 'pleaching,'" I say to Merlin, patting the fused branches. "The artist David Nash planted a circle of ash trees in a clearing in North Wales, then bent and wove the trees so that they grew not just next to one another but into one another, a dancing 'Ash Dome,' made of a meld of boughs and limbs."

"Actually," says Merlin, "plant scientists have a technical term for this. We call it 'snogging,' or to give it its full name, 'tree snogging.'" He smiles. "Well, not quite. The technical term is actually 'inosculation,' from the Latin osculare, meaning 'to kiss.' Inosculation means 'to en-kiss.' It can happen across trees and between species too."

Though I know the word "inosculation," I had not known its etymology; what seemed a chilly specialist term gains a passionate warmth, and feels true to this arboreal "en-kissing," which makes it hard to say where one being ends and another begins. I think of Ovid's version of the "Baucis and Philemon" myth, in which an elderly couple are transformed into an intertwining oak and linden, each supporting the other in terms of both structure and sustenance, drawing strength for each other from the ground through their roots-and tenderly sharing that strength through their en-kissing. "This kind of merging happens belowground too," says Merlin, "but probably more intensely between the roots of the trees than between branches, because space is more limited belowground and the crisscrossing will be denser. And it happens vastly more profusely in the fungal networks, often between quite different species." He follows the pleaching of the two branches with a finger.

"From being two hyphal tubes, two fungi are suddenly one, and things can start flowing between them, including genetic material and nuclei. This is why it's so hard to deal with species concepts in fungi, or even the question of what an organism is-because while fungi do the sex thing, they also have this wildly promiscuous horizontal transfer of genetic material that is unpredictable in a still ill-understood way."

Merlin Sheldrake, as the oldest joke in mycology goes, is a fun guy to be around. During the days in which he conjures open the underland of Epping Forest for me, I ask more questions than I have of anyone for what feels like years. What he tells and shows me in that modest peri-urban forest reshapes my sense of the world in ways I am still processing.

The night of Merlin's birth was three days after the Great Storm of 15 October 1987, when hurricane-force winds, gusting to strengths of 120 mph, capsized carriers, drove ferries ashore, and felled some 15 million trees-ripping up the forest floor across southern England and northern France and tilting it skywards in the form of root plates. The first full day of Merlin's life was "Black Monday," when the Dow Jones suffered a record fall, wiping trillions off global wealth and triggering a crash in financial markets worldwide.

No, the omens of Merlin Sheldrake's arrival into the world were not auspicious. In Greek myth he would surely have been fated to be a force for destruction and ruin. But he was given a magical name and he grew into a magical person. He is tall, slim, and very upright in his bearing. He has tight curls of dark hair, intense eyes with full circles of white visible around each iris, and a wide, warm grin. He is also a formidable scientist, with a doctorate in Plant Science from Cambridge. There is something faintly antiquarian to him-a disinterest in disciplinary boundaries, a boundless curiosity-and something of the heroic-age plant hunter too. He puts me in mind of a cross between Sir Thomas Browne and Frank Kingdon-Ward, collector of Meconopsis betonicifolia, the legendary blue poppy of the Himalayas.

It is typical of Merlin that he became fascinated from a young age not with the charismatic megafauna of the world, but instead with the undersung, underseen inhabitants of the biota: lichens, mosses, and fungi. He studied them as an amateur teenage scientist, counting lichen species on gravestones and granite boulders, and trying to comprehend the subterranean architecture of fungal life-aboveground mushrooms as fruiting bodies that stand as mere fleeting allusions to immense underland structures.

"My childhood superheroes weren't Marvel characters," Merlin once said to me, "they were lichens and fungi. Fungi and lichen annihilate our categories of gender. They reshape our ideas of community and cooperation. They screw up our hereditary model of evolutionary descent. They utterly liquidate our notions of time. Lichens can crumble rocks into dust with terrifying acids. Fungi can exude massively powerful enzymes outside their bodies that dissolve soil. They're the biggest organisms in the world and among the oldest. They're world-makers and world-breakers. What's more superhero than that?"

Old coppice trees left uncut, hydra-headed pollards. A fallen log, thick with moss; small orange fungi sprouting from wet breaks in its grain.

Merlin and I set off on foot into Epping Forest one morning from a high clearing, heading roughly north, keeping the sun to the right of our line.

Epping extends to the northeast of London, and it is very far from a wildwood. It was first designated as a royal hunting forest in the twelfth century by Henry II, with penalties for poaching that included imprisonment and mutilation. Presently it is managed by the City of London Corporation, and has more than fifty bylaws governing behavior within its bounds-though the punishments are now fiscal rather than corporal. It is fully contained within the M25, the orbital motorway that encircles outer London. Minor roads traverse it, and it is never more than two and a half miles wide. Despite its small extent, Epping is easy to get lost in-a forest of forking paths to which, for a thousand years, the people of London and its surrounds have gone for shelter, sex, escape, and a relic greenwood magic.

Growl of roads. Whirr of a low-flying bumblebee, stirring the leaf litter with its downdraft. Buzzard overhead, turning, mewing. Old coppice trees left uncut, hydra-headed pollards. A fallen log, thick with moss; small orange fungi sprouting from wet breaks in its grain. Where trees thin out and light falls, hundreds of green beech seedlings are pushing up through the litter, none more than an inch high. Five fallow deer appear between hollies ahead of us, the dapple of leaf-light flicking off the dapple of their flanks as they move through the understory.

In the language of forestry and forest ecology, the "understory" is the name given to the life that exists between the forest floor and the tree canopy: the fungi, mosses, lichens, bushes, and saplings that thrive and compete in this mid-zone. Metaphorically, though, the "understory" is also the sum of the entangled, ever-growing narratives, histories, ideas, and words that interweave to give a wood or forest its diverse life in culture.

"What interests me most," says Merlin, "is the understory's understory." He points around at the beech, the hornbeam, the chestnut. "All of these trees and bushes," he says, "are connected with one another belowground in ways we not only cannot see, but ways we have scarcely begun to understand."

While studying Natural Sciences at Cambridge, Merlin read Simard's groundbreaking research into the wood wide web. He also read E. I. Newman's classic 1988 paper, "Mycorrhizal Links between Plants: Their Functioning and Ecological Significance." There Newman argued against the assumption that "plants are physiologically separate from each other," proposing instead the existence of a "mycelial network" that might link plants together. "If this phenomenon is widespread," wrote Newman, "it could have profound implications for the functioning of ecosystems."

Those "implications" were indeed profound, and they fascinated Merlin. He already loved the alien realm of fungi. He knew that fungi could turn rocks to rubble, could move with swiftness both overground and underground, could reproduce horizontally, and digest food outside their bodies by means of metabolically ingenious excreted acids. He knew that their toxins could kill us, and their psychoactive chemicals could induce hallucinogenic states. The work of Simard and Newman, however, revealed to him that fungi could also allow plants to communicate with one another.

Merlin was taught as an undergraduate by Oliver Rackham, the legendary botanist whose research transformed our understanding of both the cultural and botanical history of the English landscape. Working with Rackham, Merlin found himself most intellectually attracted to places where orthodox evolutionary theory felt thinnest-and for him the thinnest places were where mutualisms were at work. Mutualism is a subset of symbiosis in which there exists between organisms a prolonged relationship that is interdependent and reciprocally beneficial.

"What fascinates me about mutualisms," says Merlin, "is that one would predict from basic evolutionary theory that they would be massively unstable, and collapse quickly into parasitism. But it turns out that there are very ancient mutualisms, which have remained stable for puzzlingly long times: between the yucca plant and yucca moths, for example, or of course between the bacteria that illuminate the bioluminescent headlamp of the bobtail squid, and the squid itself."

"Of course," I reply. "The ancient glowing-bobtail-squid-and-bacteria mutualism."

"The ultimate mutualism, though," says Merlin, "is between plants and mycorrhizal fungi."

"All of these trees and bushes are connected with one another belowground in ways we not only cannot see, but ways we have scarcely begun to understand."

Merlin Sheldrake

The term "mycorrhiza" is made from the Greek words for "fungus" and "root." It is itself a collaboration or entanglement; and as such a reminder of how language has its own sunken system of roots and hyphae, through which meaning is shared and traded.

The relationship between mycorrhizal fungi and the plants they connect is ancient-around 450 million years old-and largely one of mutualism. In the case of the tree-fungi mutualism, the fungi siphon off carbon that has been produced in the form of glucose by the trees during photosynthesis, by means of chlorophyll that the fungi do not possess. In turn, the trees obtain nutrients such as phosphorus and nitrogen that the fungi have acquired from the soil through which they grow, by means of enzymes that the trees lack.

The possibilities of the wood wide web far exceed this basic exchange of goods between plant and fungi, though. For the fungal network also allows plants to distribute resources between one another. Sugars, nitrogen, and phosphorus can be shared between trees in a forest: a dying tree might divest its resources into the network to the benefit of the community, for example, or a struggling tree might be supported with extra resources by its neighbors.

Even more remarkably, the network also allows plants to send immune-signaling compounds to one another. A plant under attack from aphids can indicate to a nearby plant via the network that it should up-regulate its defensive response before the aphids reach it. It has been known for some time that plants communicate aboveground in comparable ways, by means of diffusible hormones. But such airborne warnings are imprecise in their destinations. When the compounds travel by fungal networks, both the source and recipient can be specified. Our growing comprehension of the forest network asks profound questions: about where species begin and end, about whether a forest might best be imagined as a super-organism, and about what "trading," "sharing," or even "friendship" might mean between plants and, indeed, between humans.

The anthropologist Anna Tsing likens the belowground of a forest to "a busy social space," where the interaction of millions of organisms "forms a cross-species world underground." "Next time you walk through a forest," she writes memorably in an essay called "Arts of Inclusion, or How to Love a Mushroom," "look down. A city lies under your feet."

The possibilities of the wood wide web far exceed this basic exchange of goods between plant and fungi.

In the underland of the hardwood forests of Oregon's Blue Mountains there exists a honey fungus, Armillaria solidipes, that is two and a half miles in extent at its widest point, and covers a total lateral area of almost four square miles. The blue whale is to this honey fungus as an ant is to us. It is a deeply mysterious organism: the largest in the world that we know of, and one of the oldest. The best guess that US Forest Service scientists have been able to offer for the honey fungus's age is between 1,900 and 8,650 years old. The fungus expresses itself aboveground as mushrooms with white-flecked stems rising to tawny, gill-frilled cups. Belowground, where its true extent lies, Armillaria solidipes moves as rhizomorphs resembling black bootlaces, out of which reach the hyphal fingers of its mycelium, spreading in search both of new hosts which they might kill, and the mycelia of other parts of the colony with which they might fuse.

All taxonomies crumble, but fungi leave many of our fundamental categories in ruin. Fungi thwart our usual senses of what is whole and singular, of what defines an organism, and of what descent or inheritance means. They do strange things to time, because it is not easy to say where a fungus ends or begins, when it is born or when it dies. To fungi, our world of light and air is their underland, into which they tentatively ascend here and there, now and then.

Fungi were among the first organisms to return to the blast zone around the impact point in Hiroshima, the point from which the mushroom cloud had risen. After Hiroshima, too, images of the mushroom cloud began to appear ubiquitously in media and culture-the fruiting bodies of a new global anxiety. Scientists working in Chernobyl after the disaster there were surprised to discover fine threads of melanized fungi lacing the distressed concrete of the reactor itself, where radiation levels were over 500 times higher than in the normal environment. They were even more surprised to work out that the fungi were actively thriving due to the high levels of ionizing radiation: that they benefited from this usually lethal gale, increasing their biomass by processing it in some way. Ecologists in the US seeking to understand how American trees will respond to the stress of climate change have begun to focus on the presence of soil fungi as a key indicator of future forest resilience. Recent studies suggest that well-developed fungal networks will enable forests to adapt faster at larger scales to the changing conditions of the Anthropocene.

"Learning to see mosses is more like listening than looking," writes the ethnobotanist Robin Wall Kimmerer; "mosses ... issue an invitation to dwell for a time right at the limits of ordinary perception." Learning to see fungi seems even harder-requiring senses and technologies that we have yet to develop. Even to try and think with or as fungi is valuable, though, drawing us as it does towards lifeways that are instructively beyond our ken.

Certainly, orthodox "Western" understandings of nature feel inadequate to the kinds of world-making that fungi perform. As our historical narratives of progress have come to be questioned, so the notion of history itself has become remodeled. History no longer feels figurable as a forwards-flighting arrow or a self-intersecting spiral; better, perhaps, seen as a network branching and conjoining in many directions. Nature, too, seems increasingly better understood in fungal terms: not as a single gleaming snow-peak or tumbling river in which we might find redemption, nor as a diorama that we deplore or adore from a distance-but rather as an assemblage of entanglements of which we are messily part. We are coming to understand our bodies as habitats for hundreds of species of which Homo sapiens is only one, our guts as jungles of bacterial flora, our skins as blooming fantastically with fungi.

Yes, we are beginning to encounter ourselves-not always comfortably or pleasantly-as multi-species beings already partaking in timescales that are fabulously more complex than the onwards-driving version of history many of us still imagine ourselves to inhabit. The work of the radical biologist Lynn Margulis and others has shown humans to be not solitary beings, but what Margulis memorably calls "holobionts"-collaborative compound organisms, ecological units "consisting of trillions of bacteria, viruses and fungi that coordinate the task of living together and sharing a common life," in the philosopher Glenn Albrecht's phrase.

Little of this thinking is new, however, when viewed from the perspective of animist traditions of indigenous peoples. The fungal forest that science had revealed to Merlin and that Merlin was revealing to me-a forest of arborescent connections and profuse intercommunication-seemed merely to provide a materialist evidence-base for what the cultures of forest-dwelling peoples have known for thousands of years. Again and again within such societies, the jungle or woodland is figured as aware, conjoined, and conversational. "To dwellers in a wood almost every species of tree has its voice as well as its feature," wrote Thomas Hardy in Under the Greenwood Tree. The anthropologist Richard Nelson describes how the Koyukon people of the forested interior of what we now call Alaska "live in a world that watches, in a forest of eyes. A person moving through nature-however wild, remote ... is never truly alone. The surroundings are aware, sensate, personified. They feel." In such a vibrant environment, loneliness is placed in solitary confinement.

There in the grove with Merlin, I recall Kimmerer, Hardy, and Nelson, and feel a sudden, angry impatience with modern science for presenting as revelation what indigenous societies take to be self-evident. I remember Ursula Le Guin's angrily political novel, set on a forest planet in which woodland beings known as the Athsheans are able to transmit messages remotely between one another, signaling through the medium of trees. On Athshe-until the arrival of colonists committed to the planet's exploitation-the realm of mind is integrated into the community of the trees, and "the word for world is forest."

All taxonomies crumble, but fungi leave many of our fundamental categories in ruin.

What is at stake is not only the relations of nature but also the nature of relations.

Potawatomi, a Native American language of the Great Plains region, includes the word puhpowee, which might be translated as "the force which causes mushrooms to push up from the earth overnight." In "all its technical vocabulary," Robin Wall Kimmerer notes, "Western science has no such term, no words to hold this mystery."

Kimmerer herself is a member of the Citizen Potawatomi Nation. A speaker of what she calls "fluent botany," she is careful to distinguish this from what she refers to as "the language of plants"-that is to say, the language that plants speak, as opposed to the language that is used to speak of plants. Kimmerer does not disdain the precisions of botanical lexis, which "polishes the gift of seeing," but she finds it also to be of necessity a lexis of objectification and distancing, with something missing beneath its finely faceted surface. That missing something is predominantly the acknowledgment of life in the more-than-human world, an indifference which is grained into language not just at the level of individual words, but at the deeper-down levels of grammar and syntax.

In Potawatomi, by contrast, almost all words declare the animacy or inanimacy of that to which they refer. The language is predisposed to recognize life in otherness, and also to extend the reach of that category of "life" far beyond its familiar limits in Western thought. In Potawatomi, not only humans, animals and trees are alive, but so too are mountains, boulders, winds, and fire. Stories, songs, and rhythms are all also animate, they are, they be. Potawatomi is a language abundant with verbs: 70 percent of its words are verbs, compared to 30 percent in English. Wiikwegamaa, for instance, means "to be a bay." "A bay is a noun only if water is dead," writes Kimmerer:

trapped between its shores and contained by the word. But the verb ... releases the water from bondage and lets it live. "To be a bay" holds the wonder that, for this moment, the living water has decided to shelter itself between these shores, conversing with cedar roots and a flock of baby mergansers.

Like Kimmerer, I wish for a language that recognizes and advances the animacy of the world, "the life that pulses through pines and nuthatches and mushrooms ... well[ing] up all around us." Like Kimmerer, I relish those aspects of discourse that extend being and sentience respectfully and flexibly beyond the usual bearers of such qualities. Like Kimmerer I believe that we need, now, a "grammar of animacy." A modern predisposition to regard animacy as anomaly runs through what the poet Jeremy Prynne once called "mammal language," by which he means the language that is used by humans, encoding intent, agency, and muscular power deep in its grammar.

The real underland of language is not the roots of single words, but rather the soil of grammar and syntax, where habits of speech and therefore also habits of thought settle and interact over long periods of time. Grammar and syntax exert powerful influence on the proceedings of language and its users. They shape the ways we relate to each other and to the living world. Words are world-makers-and language is one of the great geological forces of the Anthropocene.

Projects have recently been started around the world to gain even the most basic of vocabularies for the experiences of life and death in the Anthropocene. These stuttering attempts to speak what it is we are doing have generated ugly new terms for an ugly epoch: "geotraumatics," "planetary dysphoria," "apex-guilt." Such words feel like futile forms of nominalism, a hopelessly hyperactive pointing and naming. They stick in the throat in two ways: they are difficult to utter and hard to swallow.

Only one of these recent coinages resonates with me: "species loneliness," for the intense solitude that we are fashioning for ourselves as we strip the Earth of the other life with which we share it. If there is human meaning to be made of the wood wide web, it is surely that what might save us as we move forwards into the precarious, unsettled centuries ahead is collaboration: mutualism, symbiosis, the inclusive human work of collective decision-making extended to more-than-human communities.
You look at the network, and then it starts to look back at you ...
Writing of mycorrhizal fungi, Albrecht proposes that we rechristen the Anthropocene, naming it instead the Symbiocene-an epoch characterized in terms of social organization "by human intelligence that replicates the symbiotic and mutually reinforcing life-reproducing forms and processes found in living systems ... such as the wood wide web."
The word for world is forest.

I wish for a language that recognizes and advances the animacy of the world.

In this in-depth interview, writer Robert Macfarlane articulates the consequence, the responsibility, as well as the pleasure of naming the living world.

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Excerpted from his recently published book, Underland: A Deep Time Journey, "The Understory" is an examination of the life beneath the forest floor. Encountering the depth and complexity of communication that happens underground, Robert returns to the entangled mutualism at the root of language.

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Scientists once ridiculed the idea of a living planet. Not anymore.

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Opinion | The Earth Is Just as Alive as You Are (Published 2019)

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Scientists once ridiculed the idea of a living planet. Not anymore.

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Exposure of Insects to Radio-Frequency Electromagnetic Fields from 2 to 120 GHz

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Exposure of Insects to Radio-Frequency Electromagnetic Fields from 2 to 120 GHz

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Insects are continually exposed to Radio-Frequency (RF) electromagnetic fields at different frequencies. This paper is the first to report the absorbed RF electromagnetic power in four different types of insects as a function of frequency from 2 GHz to 120 GHz.

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Abstract

Insects are continually exposed to Radio-Frequency (RF) electromagnetic fields at different frequencies. The range of frequencies used for wireless telecommunication systems will increase in the near future from below 6 GHz (2 G, 3 G, 4 G, and WiFi) to frequencies up to 120 GHz (5 G). This paper is the first to report the absorbed RF electromagnetic power in four different types of insects as a function of frequency from 2 GHz to 120 GHz. A set of insect models was obtained using novel Micro-CT (computer tomography) imaging. These models were used for the first time in finite-difference time-domain electromagnetic simulations. All insects showed a dependence of the absorbed power on the frequency. All insects showed a general increase in absorbed RF power at and above 6 GHz, in comparison to the absorbed RF power below 6 GHz. Our simulations showed that a shift of 10% of the incident power density to frequencies above 6 GHz would lead to an increase in absorbed power between 3-370%.

Introduction

Radio-Frequency (RF) electromagnetic fields (EMFs) enable wireless communication between billions of users worldwide. Presently, this mainly occurs at RF frequencies located between 100 MHz and 6 GHz1. Wireless telecommunication base stations are the dominant sources of outdoor RF-EMFs1. Humans and animals alike are exposed to these fields, which are partially absorbed by their bodies, e.g. reported for insects in2. The absorbed dose depends on the frequency3,4, and can be strongly enhanced when a full-body or partial-body resonance occurs3. This RF absorption has already been studied for particular insects at different individual frequencies: 27 MHz5,6, 900-915 MHz, and 2450 MHz9.

This absorption may cause dielectric heating10. Heating affects insect behavior, physiology, and morphology11. Reviews of studies that investigate RF heating of insects are presented in. Other authors focus on environmental RF exposure of insects15,16 or expose insects to RF radiation in order to investigate potential biological effects17,18. Studies on non-thermal effects of exposure to RF-EMF exist:19 presents a review of potential mechanisms for non-thermal effects and a review of non-thermal effects of EMF exposure wildlife is presented in20. Most existing studies focus on RF frequencies below 6 GHz. The same frequencies at which the current generations of telecommunication operate1. However, due to an increased demand in bandwidth, the general expectation is that the next generation of telecommunication frequencies will operate at so-called millimeter-wavelengths: 30-300 GHz21,22. Therefore, future wavelengths of the electromagnetic fields used for the wireless telecommunication systems will decrease and become comparable to the body size of insects and therefore, the absorption of RF-EMFs in insects is expected to increase. Absorption of RF energy was demonstrated in insects between 10-50 GHz23, but no comparison was demonstrated with the RF absorption at frequencies below 10 GHz. The radar cross section of insects has been determined above 10 GHz, but this quantity includes both scattering and absorption24. It is currently unknown how the total absorbed RF power in insects depends on the frequency to which they are exposed.

Most of the previously cited studies depend on measurements using RF equipment such as antennas, waveguides, and dielectric probes to determine the absorption of RF-EMFs in insects. An alternative approach would be to use numerical simulations. This approach was previously used to determine the absorption of RF-EMFs in humans and requires numerical models or phantoms25,26,27,28.

Techniques for creating heterogeneous, three-dimensional insect models with micrometer resolution have previously been demonstrated in29.

However, up to now, insect phantoms have not been used in electromagnetic simulations.

The aims of this study were to, for the first time, numerically evaluate RF-EMF absorption in real models of insects and to determine a potential difference in RF absorption in insects due to current and future telecommunication networks. To this aim, we studied the absorbed RF power in four different insect models obtained using micro-CT imaging as a function of frequency in a broad band, 2 GHz up to 120 GHz, that covers both the existing and the foreseen future wireless telecommunication bands. Voxelling precision in the order of 5-20  μ m is obtained, required for accurate electromagnetic simulations.

Methods

The Insects

Australian Stingless Bee (Tetragonula carbonaria)

This bee (Tetragonula carbonaria) is native to Australia. The scanned insect was approximately 4.5 mm long, 3.0 mm wide, and has a mass of 2.5 mg.

Western Honeybee (Apis mellifera)

This bee (Apis mellifera) originated in Europe. It is the most common honeybee. The studied specimen was approximately 11.0 mm long, 5.0 mm wide, and has a mass of 900 mg.

Desert Locust (Schistocerca gregaria)

The studied locust (Schistocerca gregaria) was approximately 55.0 mm long, 18.0 mm wide, and has an approximate mass of 3.5 g.

Beetle (Geotrupes stercorarius)

The studied beetle is a dor beetle (Geotrupes stercorarius). The beetle was found and scanned (see below) at Aberdeen University in Scotland. The beetle's length was 8.01 mm and its width is 4.5 mm. The insect's mass was not measured at the time of scanning. The average mass of a dor beetle is 220 mg30.

Scanning Methods

Australian Stingless Bee

MicroCT scans were performed with a Skyscan 1172 high-resolution MicroCT system (Bruker MicroCT, Kontich, Belgium). This system has a sealed, microfocus x-ray tube with a 5  μm focal spot size. The x-rays were produced by exposing the anode to 40 kV at 100  μA. Prior to scanning, the sample containing the insect was placed on the pedestal between the x-ray source and the CCD detector. After positioning the sample, 600 2D x-ray images over 180° were captured by exposing the sample and then rotating it to the next exposure position with a slice-to-slice rotation distance of 2  μm, and a total acquisition time of approximately 60 min: each 2D image represents one slice. The scanner software then converted each slice to axial orientation and created 998 bitmap images (16 bit grey scale) which were stored for 2D viewing and 3D reconstruction as a 983 Mb dataset. The resulting isotropic voxel size was 5  μ m.

Western Honeybee

A bench-top MicroCT scanner (Quantum GX MicroCT Imaging System, PerkinElmer, Hopkinton, MA, USA) at the Western Sydney University National Imaging Facility (Sydney, Australia) was used to scan the bee. The following parameters were used: 50 kVp, 80  μA, high resolution 2048 × 2048 pixels image matrix, with 20  μ m isotropic voxel size. Scanning time was 3.0 s for each of the 180 projections with 3.0 s rotation in between each projection. The total scan time was approximately 18 min per whole bee. The Quantum GX, bench-top MicroCT scanner's software was used to reconstruct the 180 projection images and then to convert them into a 2D rendered image stack of 512, 16 bit bitmap images. Bee volume data were then acquired by loading the image stack into BeeView volume rendering software (DISECT Systems Ltd, Suffolk, UK).

Desert Locust

The locust was suspended vertically in a 30-mm acrylic tube that was mounted tightly on the micro-CT's inclination stage. This stage was used to ensure that the rotation axis was at 90° to the x-ray source. Exposure factors were: 50 kVp and 198  μA. The data were isotropic 16 bit 2000 × 2000 pixels with 1048 rows. Pixel size was 10.469  μm. Skyscan NRecon software version 1.5.1.4 (Bruker, Kontich, Belgium) was used to reconstruct the projection data31. Having obtained the projection data in the form of an image stack of 2-D TIFF files the data was viewed as a 3-D model using Disect software, DISECT Systems29.

Beetle

The beetle was scanned at Aberdeen University on a Skyscan 1072 Micro-CT scanner (Bruker, Kontich, Belgium) using 50 kV and 197  μA, at 10.46  μm pixels isotropically. The images were then converted to axial slices using Skyscan's NRECON software (version 1.4). The produced axial image stack was further processed and analyzed using the Tomomask software ( www.tomomask.com) before viewing in disect.

Development of 3D models

3D models of the insects were created using the software TomoMask ( www.tomomask.com). The image stack for each insect was firstly imported into the software together with details of the pixel and slice spacing. Regions to be converted into a 3D model are defined in TomoMask by drawing a mask of the wanted regions on each slice. This can be done automatically using the Luminance mask function which creates a mask based on the grey level of the pixels. The threshold values for the mask are set to include all of the insect tissue but will exclude air cavities and very fine structures, such as wings. The 3D model (generated by a marching cubes algorithm32) is exported as an STL (STereo Lithography)33 format file. STL files describe only the surface geometry of a three-dimensional object without any representation of colour or texture. Typically some smoothing of the models is required and this is realized using the Taubin λ/ μ smoothing scheme34 implemented in MeshLab35. The Taubin method is good at removing noise whilst preserving shapes and features. Dimensions of the models and mesh integrity are finally checked (and corrected if necessary) using Netfabb (Autodesk, San Rafael, CA, USA).

Dielectric Properties

The propagation of EMFs inside and around the obtained 3D insect phantoms will depend on their dielectric properties: the relative permittivity ( ε r) and conductivity ( σ). In this study, we have executed and relied on a literature review of previous measurements of dielectric properties of insects, predominantly using the coaxial-line probe method36. There exist alternative methods. A toroidal resonator was used to determine the dielectric properties of two insects at 2370 MHz37. Dielectric properties of Rice Weevils (Sitophilus oryzae) are obtained using the coaxial probe method for frequencies from 5 × 10 4-2 × 10 10 Hz2. The same technique was used on three other insects: the Red Flour Beetle (Tribolium castaneum), the Sawtooth Grain Beetle (Oryzaephilus surinamensis), and the Lesser Grain Borer (Rhyzopertha dominica), from 0.2-20 GHz36. The same method was also used to measure dielectric properties of four insects: the Codling Moth (Cydia pomonella), the Indian Mealmoth (Plodia interpunctella), the Mexican fruit fly (Anastrepha ludens), and the Navel Orange Worm (Amyelois transitella) from 27-1800 MHz6. Coaxial measurements on a Colorado Beetle (Leptinotarsa decemlineata) were performed from 0.1-26.5 GHz and used to derive a fit to the measurement data38.

We have pooled the data series, real and imaginary part of ε r as a function of frequency, obtained by and interpolated them from 2-120 GHz in steps of 0.1 GHz. We have then averaged over all available data at every frequency steps considered in the simulations.

Numerical Simulations

The Finite-Difference Time-Domain (FDTD) technique implemented in the commercial simulation software Sim4life (ZMT, Zurich, Switzerland) is used to evaluate absorption of RF-EMFs inside the insects as a function of frequency. This technique is commonly used to determine absorption of RF-EMF in heterogeneous human body models3. The FDTD method requires one to discretize the simulation domain using a three-dimensional grid. The simulation domain is divided in a number of cubes (discretized) with spatial extends that are defined by the spatial grid steps in the simulation domain. RF-EMFs can be incident from any direction. Therefore, we have chosen to work with 12 incident plane waves with a root-mean-squared electric field strength of 1 V/m, illustrated in Fig. 1, along 6 directions defined by Cartesian axes, with two orthogonal polarizations of the incident RF-EMFs along each axis.

Figure 1

Illustration of the RF-EMF exposure set up. The insect (Beetle shown here in pink) is exposed to twelve RF plane waves incident from six directions along the positive and negative directions of the Cartesian axes shown on the bottom left with two orthogonal polarizations for each direction. The twelve wave vectors \({\overline{k}}_{i/j}\) are indicated in blue (dashed arrows), while the polarization of the incident electric fields \({\overline{E}}_{i}\) are indicated in red. i and j indicate the configuration number, from 1 to 12.

The exposure was modeled using single frequency sinusoidal (harmonic) continuous plane waves. We did not take into account a potential modulation of the waves, which might be present in real telecommunication signals. This same technique has previously been used to evaluate the frequency dependence of RF absorption in the human body3. Simulations were executed for sinusoidal plane waves at 7 harmonic (single) frequencies: 2, 3, 6, 12, 24, 60, and 120 GHz. This resulted in a dataset of 4 (insects) ×7 (frequencies) ×12 (plane waves: 6 angles of incidence ×2 polarizations) = 336 simulations.

The Australian Stingless Bee, the Western Honey Bee, and the Beetle were discretized with steps of 0.05 mm in each direction, while the larger Locust was discretized with steps of 0.2 mm in each direction at frequencies below 60 GHz and a step of 0.1 mm at 60 GHz and 120 GHz. These spatial steps provided a balance between simulation time (which depends on the number of grid steps and the relative grid step size in comparison to the wavelength) and spatial resolution of the insects' features. A stable FDTD simulation yields reproducible results that converge over time. The quantities determined using the FDTD algorithm should converge to a constant value as the simulation progresses in time. After a certain simulation time, these values will remain constant, this is referred to as a steady state. A grid step smaller than one tenth of the smallest wavelength in the simulation domain is necessary for a stable FDTD simulation39. This is a requirement of the FDTD algorithm39 and remains valid in all our simulations. The smallest wavelength in tissue \((\lambda /\sqrt{{\varepsilon }_{r}})\) is 1.1 mm at 120 GHz. At this frequency we used grid steps of 0.05 mm \((\le 0.045\times \lambda /\sqrt{{\varepsilon }_{r}})\) for all insects, except for the locust where we used 0.1 mm \((\le 0.09\times \lambda /\sqrt{{\varepsilon }_{r}})\) .

We ensured that the grid steps were small enough to prevent disconnections in the models. All insects were considered as consisting of homogeneous tissue with frequency-dependent dielectric parameters obtained as an average of the values we found in literature (previous section). This is an approximation, since real insects have heterogeneous tissue properties. Each simulation was executed until a steady state was reached. The number of periods necessary to reach a steady state solution depended on the studied insect and frequency and was between 20-80. This was controlled by temporal monitoring of the electric field strength along a line in the simulation domain until it reached a steady state. Additionally, the chosen number of simulation periods allowed for propagation of at least 3 times the length of the insects' diagonal (see Table 1).

Table 1 Dimensions of the studied insect models along the different axes shown in Fig. 1.

After every simulation, the absorbed RF-EMF power ( P abs) in the insect was extracted. The P abs is calculated as the product of the conductivity and the squared electric field strength integrated over the volume of the insect. The whole-body averaged specific absorption rate can be obtained by dividing P abs by the insects' mass (assuming a homogeneous mass density). Absorbed RF-EMF power is generally used as a proxy for dielectric tissue heating10. We have not executed full thermal simulations due to uncertainties on the specific heat capacities of the insects and heat dissipation mechanisms.

Results

3D Models

Figure 2 shows the used 3D models obtained using micro-CT scanning of four insects.

Figure 2

Frontal, side, and Top view of the four studied insects. ( a) Australian Stingless Bee, ( b) Western Honeybee, ( c) Beetle, and ( d) Locust.

Dielectric Properties

Figure 3 shows the imaginary and real parts of ε r obtained by averaging those values that were available in. The real part is positive and decreases with frequency, while the imaginary part is negative (lossy media) and shows a minimum between 10-20 GHz. These are in line with the Debye dielectric curves proposed in38. Figure 3 adds further perspective by showing the corresponding conductivity in (S/m) and the RF penetration depth.

Figure 3

From top to bottom: Real part of the used dielectric permittivity, Imaginary part of the used dielectric permittivity, and conductivity with RF-EMF penetration depth as an inset. Markers show measurements obtained from literature. The black line with circular markers shows the average over the available data series at those frequencies.

Numerical Simulations

Figure 4 illustrates the frequency dependence of the absorption of RF-EMFs in the Western Honeybee in terms of the ratio of the electric field strength inside the insect to the maximum electric field in the simulation domain. At the currently used frequencies for telecommunication (<6 GHz), the wavelength is relatively large compared to the insects and the waves do not penetrate into the insects, which results in lower Pabs values. At 12-24 GHz, the fields penetrate more and more into the insect as the wavelength becomes comparable to the insects' size and the conductivity increases as well. At the highest studied frequencies, the fields penetrate less deep into the insect, but their amplitude is higher, resulting in a similar or slightly lower P abs.

Figure 4

Normalized Electric field strength (dB) in a mid-transverse cross section of the Western Honey Bee as a function of frequency for a single plane wave incident from below with polarization orthogonal to the shown plane (No. 5 in Fig. 1). Normalization was executed for each simulation separately, i.e. E max can be different in each subfigure.

Figure 5 shows the P abs linearly averaged over all twelve plane waves as a function of frequency for all studied insects. The absorbed power increases with increasing frequency from 2-6 GHz for all insects under exposure at a constant incident power density or incident electric field strength of 1 V/m. The absorbed power in the Locust, the largest studied insect, decreases slightly at the studied frequencies >6 GHz, but remains higher than at 2 and 3 GHz. The Western Honeybee shows an increase up to 12 GHz, followed by a slight decrease up to 120 GHz (Pabs remains more than 10× higher than <6 GHz). The smaller Australian Stingless Bee shows an increase of P abs with frequency up to 60 GHz and a slight decrease at 120 GHz. The Pabs in the Beetle increases until 24 GHz and slightly decreases at higher frequencies.

Figure 5

P abs for an incident field strength of 1 V/m as a function of frequency for all studied insects. The markers indicate the average over all twelve plane waves at each of the simulated frequencies, while the whiskers indicate the minimal and maximal Pabs values obtained during the simulations.

Table 1 lists the dimensions of the different studied insects, compared to the wavelength λ-range in which the maximal Pabs will be located. The Pabs is simulated for discrete frequency steps. Therefore, the λ max that corresponds to the maximum P abs is located in between the wavelength steps right below and above the wavelength step that corresponds to the maximum simulated P abs, see Fig. 4. The main diagonal of the insects' bounding box is within the range in which the wavelength of maximal absorption λ max is located for three out of the four studied insects. This indicates that the absorption is (partly) determined by the size of the insects.

Numerical simulations are never the same as reality and there are always uncertainties associated with any EM simulation technique. We report the following sources of uncertainty: model variations and variation on dielectric properties.

The insect models are scanned with a resolution of 20  μm, 10.5  μm, 10.5  μm, and 5  μm, for the Honey Bee, the Locust, the Beetle, and the Australian Stingless Bee, respectively. These are 40%, 5-10%, 21%, and 10% of the spatial grid step used in the simulations of the Honey Bee (0.05 mm), the Locust (0.1-0.2 mm), the Beetle (0.05 mm), and the Australian Stingless Bee (0.05 mm), respectively. This indicates that the grid step is dominant in determining the spatial extends of the used models and not the resolution of the scanning method. In order to investigate the effect of the chosen grid step on the obtained P abs values, we have executed the simulation with configuration 9 (Fig. 1) at 120 GHz with a maximal grid step that is half of the grid step used in our simulations using all four studied insects. We assume the largest effect of grid step size at the highest frequency. A 50% reduction in grid step (more accurate modelling) resulted in deviations of 1.1%, 2.5%, 0.32%, and 0.24%, for the Honey Bee, the Locust, the Beetle, and the Australian Stingless Bee, respectively. These deviations are small in comparison to the variations as a function of frequency, see Fig. 5, and the uncertainty caused by the dielectric parameters, see the next paragraph.

Deviations on ε r will influence P abs: the real part of ε r will (partly) determine the magnitude of the internal electric fields, while P abs scales linearly with conductivity. The maximal relative deviations on the real and imaginary part of ε r are (−13, +36)% and (−40, +36)%, respectively, which occur between 2-3 GHz. We have executed a simulation using configuration 1 at 2 GHz for the Beetle phantom, shown in Fig. 1, using five different sets of dielectric properties accounting for the deviations mentioned above: [ Re( ε r), Im( ε r)], [1.36 ×  Re( ε r), 1.36 ×  Im( ε r)], [1.36 ×  Re( ε r), 0.6 ×  Im( ε r)], [0.87 ×  Re( ε r), 1.36 ×  Im( ε r)], and [0.87 ×  Re( ε r), 0.6 ×  Im( ε r)], in order to determine the effect of the uncertainty of dielectric properties on P abs. We found maximal relative deviations of [−57, +59]% relative to the value obtained using [ Re( ε r), Im( ε r)]. These deviations are small in comparison to the variations as a function of frequency, see Fig. 5.

Previous studies have indicated that large differences in dielectric properties might exist between adult insects and larvae40. Worst-case deviations of [ Re( ε r)/7, Im( ε r)/5] at 5  GHz and [ Re( ε r)/6, Im( ε r)/8] at 15  GHz were observed in40. We have executed simulations of configuration 1 using the beetle (shown in Fig. 1) at 6  GHz and 12  GHz where we have applied these reduced dielectric parameters. We found an increase in P abs of 4% at 6  GHz and a decrease of 66% in P abs at 12  GHz. Figure 5 shows that these variations are smaller than the variations we observed for varying angles of incidence at a fixed frequency.

Discussion

In this study, we have evaluated the absorption of RF-EMFs in insects as a function of frequency. To this aim, we obtained novel insect models using micro-CT imaging, which were used in FDTD simulations. In these simulations they were exposed to plane waves incident from six directions and two polarizations.

The frequency of the incident harmonic plane waves was varied from 2-120 GHz and resulted in P abs as a function of frequency.

Previous studies have shown that Micro-CT imaging can be successfully used as a non-invasive technique to accurately scan insects and develop 3D models with micrometer resolution29,41. Models with micrometer resolution are necessary to obtain accurate results in FDTD simulations at 120 GHz ( λ = 2.5 mm), since a discretization of λ/10 in the simulation domain is recommended to obtain stable results39. It has been demonstrated for human body models that real anatomical models generally result in more accurate and realistic results than approximate models. Therefore, we also expect our real insect models to lead to more accurate results regarding absorbed RF power than, for example, cylindrical phantoms with different diameters and heights, which were used in previous studies of RF exposure of insects42.

The dielectric properties that were assigned to the studied insects were obtained from an interpolation of data found in literature. Ideally, the simulations should be executed with dielectric properties measured in the actual insects that were used to create the models. Figure 3 does show that most insects show a similar frequency behavior, which we have averaged by using an interpolation over values listed in literature.

Our numerical simulations show that the absorption of RF-EMFs in the insect models is frequency dependent. The P abs is smallest at the lowest studied frequencies 2 GHz and 3 GHz, for all insects. P abs shows a peak, which depends on the size and/or mass of the insects. The three smaller insects show their maximum at a frequency higher than 6 GHz: 60 GHz, 24 GHz, and 12 GHz for the Australian Stingless Bee, the Beetle, and the Honey Bee, respectively. The Locust shows a maximum at 6 GHz. We attribute this frequency behavior to two effects: first, the efficiency of RF-EMFs coupling into the models is maximal at frequencies comparable to the length of the insects, as Table 1 illustrates. Second, the interpolation of the imaginary part of the dielectric constant shows a minimum at 12 GHz, which means that RF-EMFs can cause the highest local SAR at these frequencies, see Fig. 3.

The difference between the maximal and minimal P abs found at one frequency for different angles of incidence is smaller at the frequencies >6 GHz, than at the frequencies <6 GHz, in particular for the three smaller insects. This indicates that the angle of incidence is less important at these frequencies. This suggests that there is little difference in efficiency when depositing RF power in the studied insects with a single plane wave compared to depositing the same power using uncorrelated sources or reflections coming from all directions. In this study, we have only used single plane-wave simulations to determine P abs. The averaging over P abs does not include interference effects, which might result in lower (destructive interference) or higher (constructive interference) bounds on the P abs values shown in Fig. 5.

A similar frequency behavior (increase, peak, decrease, and dependency on body size) is observed in human body models3,4. However, at frequencies which are roughly a factor 100-1000 times lower, because the human body is approximately the same order of magnitude larger than that of the studied insects. For example, the heterogeneous adult human body model Duke shows an increase in Pabs from 10 MHz-80 MHz, a peak between 80 MHz-90 MHz, followed by a decrease in P abs (and a second peak at higher frequencies)3. The smaller child phantom Thelonius shows an increase in Pabs from 10 MHz-100 MHz, a peak between 100 MHz-200 MHz, followed by a decrease in P abs 3.

In order to quantify the effect of a shift to higher telecommunication frequencies on P abs, one can use the data presented in Fig. 5. If we assume an incident E rms = 1 V/m which is uniformly distributed over 2, 3, and 6 GHz, we find average P abs values of 0.71 nW, 2.6 nW, 5.7 nW, and 990 nW, for the Australian Stingless Bee, the Beetle, the Honey Bee, and the Locust, respectively. If we assume that 10% of this incident field would be evenly distributed over the frequencies above 6 GHz, the P abs increases to 2.6 nW, 7.7 nW, 14 nW, and 1.0  μW, for the Australian Stingless Bee, the Beetle, the Honey Bee, and the Locust, respectively. These are increases of 370%, 290%, 240%, and 3%, respectively. Note that this is a conservative estimation of the increase in P abs, since we assume a constant incident field and a uniform distribution of the currently used frequencies <6 GHz. Nowadays, most of the incident power density used for telecommunication is located at frequencies ≤2 GHz1, where all insects show a minimal P abs. In an isolated approximation (no convection or conduction) and under the assumption of unchanging mass and specific heat capacitance, the rate of temperature increase scales linearly with increasing P abs. As an example, for the Australian Stingless Bee (mass = 2.5 mg) a P abs of 3 × 10-8 W is estimated for an incident field strength of 1 V/m at 60 GHz. Under the assumption that the insect has a specific heat capacity equal to that of water (4179 J/K kg43), this RF-EMF exposure would result in a temperature increase of 3 × 10-6 K/s, in an isolated approximation.

Strengths and Limitations

Our paper has several clear strengths and contributions to the state of the art in literature. To our knowledge, this is the only paper in which real insects are used to create models for numerical simulations. Moreover, this is the first paper that investigates the exposure of electric fields with RF frequencies associated with 5 G wireless communication and that shows that the absorbed power in insects is expected to increase in unchanged environmental conditions with respect to the one of current wireless communication systems (3 G and 4 G). A disadvantage of our study is the use of homogeneous models in the simulations, whereas real insects will have heterogeneous tissue parameters. Variations on dielectric parameters can exist on a scale that is smaller than the spatial resolution that any scanning method can currently obtain44. The FDTD method requires a division of the simulation domain in a number of voxels, which each have to be assigned homogeneous dielectric properties39. Any numerical simulation will be an approximation of reality. To our knowledge, the FDTD method, although faced with uncertainties is the best simulation method currently available to estimate the quantities studied in this manuscript. This paper is limited to electromagnetic dosimetry, which is focused on determining absorbed powers values. These can be used as an input in thermal modelling of the insects. However, a full thermal analysis was outside the scope of this paper. Finally, we have included variations in angles and polarizations of incident waves. However, we have only looked at a limited number of plane waves, whereas real exposure is composed of plane waves from any direction.

Future Research

In our future research, we would like to model more insects to get a better understanding of the frequency dependence of the absorbed RF-EMF power as a function of insect size. We would also like to develop heterogeneous insect models with tissue-specific dielectric parameters. Finally, our goal is to determine the effect of absorption of RF-EMFs on the core temperature of insects as a function of frequency. To this aim, we want to use infrared temperature measurements of insects exposed to high electromagnetic fields as function of frequency.

Conclusions

We investigated the absorbed radio-frequency electromagnetic power in four different real insects as a function of frequency from 2-120 GHz. Micro-CT imaging was used to obtain realistic models of real insects. These models were assigned dielectric parameters obtained from literature and used in finite-difference time-domain simulations. All insects show a dependence of the absorbed power on the frequency with a peak frequency that depends on their size and dielectric properties. The insects show a maximum in absorbed radio frequency power at wavelengths that are comparable to their body size. They show a general increase in absorbed radio-frequency power above 6 GHz (until the frequencies where the wavelengths are comparable to their body size), which indicates that if the used power densities do not decrease, but shift (partly) to higher frequencies, the absorption in the studied insects will increase as well. A shift of 10% of the incident power density to frequencies above 6 GHz would lead to an increase in absorbed power between 3-370%. This could lead to changes in insect behaviour, physiology, and morphology over time due to an increase in body temperatures, from dielectric heating. The studied insects that are smaller than 1 cm show a peak in absorption at frequencies (above 6 GHz), which are currently not often used for telecommunication, but are planned to be used in the next generation of wireless telecommunication systems. At frequencies above the peak frequency (smaller wavelengths) the absorbed power decreases slightly.

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Acknowledgements

This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 665501 with the research Foundation Flanders (FWO). A.T. is an FWO [PEGASUS] 2 Marie Skłodowska-Curie Fellow. The Eva Crane Trust (Charitable Incorporated Organisation Number: 1175343) has partly funded the insect data collection, which was used for this study by M.K.G.

Author information

Affiliations

Department of Information Technology, Ghent University - imec, Ghent, B-9052, Belgium

Arno Thielens

, Luc Martens

& Wout Joseph

Department of Electrical Engineering and Computer Sciences, University of California Berkeley, Berkeley Wireless Research Center, Berkeley, CA, 94704, USA

Department of Science and Technology, Faculty of Health and Science, University of Suffolk, Ipswitch, IP30AQ, United Kingdom

Newbourne Solutions Ltd, Newbourne, Woodbridge, IP12 4NR, United Kingdom

Charles Sturt University, Medical Imaging, SDHS, Faculty of Science, Wagga Wagga, NSW 2678, Australia

Contributions

A.T. conducted the numerical simulations, analyzed the results, and drafted the manuscript, M.K.G., D.B., and, D.B.M. conducted the imaging and post processing of the imaging. W.J. and L.M. contributed to analyzing the methodology and results. All authors reviewed the manuscript and provided input to the different sections.

Competing Interests

The authors declare no competing interests.

Corresponding author

Correspondence to Arno Thielens.

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DOI
https://doi.org/10.1038/s41598-018-22271-3

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Exposure of Insects to Radio-Frequency Electromagnetic Fields from 2 to 120 GHz

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Insects are continually exposed to Radio-Frequency (RF) electromagnetic fields at different frequencies. The range of frequencies used for wireless telecommunication systems will increase in the near future from below 6 GHz (2 G, 3 G, 4 G, and WiFi) to frequencies up to 120 GHz (5 G).

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The book circles toward a central argument: that the awakening of ecological consciousness requires the acknowledgment and celebration of our reciprocal relationship with the rest of the living world

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As a botanist, Robin Wall Kimmerer has been trained to ask questions of nature with the tools of science. As a member of the Citizen Potawatomi Nation, she embraces the notion that plants and animals are our oldest teachers.

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Richard Mabey The Cabaret of Plants: Botany and the Imagination 

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Richard Mabey The Cabaret of Plants: Botany and the Imagination 

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Plants, Mabey believes, are more than simply attractive or useful, having “strange existences and unquantifiable powers”, which lend them “alternative solutions to living”. It is not ridiculous, although he says he is “embarrassed” to think of them as having “selves”.

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The Cabaret of Plants: Botany and the Imagination by Richard Mabey review - a hymn to flower power

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Richard Mabey's remarkable study of plants is a rhapsodic labour of love

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Jeremy Narby - Intelligence in Nature | Bioneers

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Jeremy Narby - Intelligence in Nature | Bioneers

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Weaving together issues of animal cognition, evolutionary biology and psychology, Narby challenges contemporary scientific concepts and reveals a much deeper view of the nature of intelligence and of our kinship with all life.

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Jeremy Narby - Intelligence in Nature | Bioneers

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Laura Ruggles, philosophy PhD candidate at the University of Adelaide in Australia

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At first glance, the Cornish mallow ( Lavatera cretica) is little more than an unprepossessing weed. It has pinkish flowers and broad, flat leaves that track sunlight throughout the day. However, it's what the mallow does at night that has propelled this humble plant into the scientific spotlight. Hours before the dawn, it springs into action, turning its leaves to face the anticipated direction of the sunrise. The mallow seems to remember where and when the Sun has come up on previous days, and acts to make sure it can gather as much light energy as possible each morning. When scientists try to confuse mallows in their laboratories by swapping the location of the light source, the plants simply learn the new orientation.

What does it even mean to say that a mallow can learn and remember the location of the sunrise? The idea that plants can behave intelligently, let alone learn or form memories, was a fringe notion until quite recently. Memories are thought to be so fundamentally cognitive that some theorists argue that they're a necessary and sufficient marker of whether an organism can do the most basic kinds of thinking. Surely memory requires a brain, and plants lack even the rudimentary nervous systems of bugs and worms.

However, over the past decade or so this view has been forcefully challenged. The mallow isn't an anomaly. Plants are not simply organic, passive automata. We now know that they can sense and integrate information about dozens of different environmental variables, and that they use this knowledge to guide flexible, adaptive behaviour.

For example, plants can recognise whether nearby plants are kin or unrelated, and adjust their foraging strategies accordingly. The flower Impatiens pallida, also known as pale jewelweed, is one of several species that tends to devote a greater share of resources to growing leaves rather than roots when put with strangers - a tactic apparently geared towards competing for sunlight, an imperative that is diminished when you are growing next to your siblings. Plants also mount complex, targeted defences in response to recognising specific predators. The small, flowering Arabidopsis thaliana, also known as thale or mouse-ear cress, can detect the vibrations caused by caterpillars munching on it and so release oils and chemicals to repel the insects.

Plants also communicate with one another and other organisms, such as parasites and microbes, using a variety of channels - including 'mycorrhizal networks' of fungus that link up the root systems of multiple plants, like some kind of subterranean internet. Perhaps it's not really so surprising, then, that plants learn and use memories for prediction and decision-making.

What does learning and memory involve for a plant? An example that's front and centre of the debate is vernalisation, a process in which certain plants must be exposed to the cold before they can flower in the spring. The 'memory of winter' is what helps plants to distinguish between spring (when pollinators, such as bees, are busy) and autumn (when they are not, and when the decision to flower at the wrong time of year could be reproductively disastrous).

In the biologists' favourite experimental plant, A thaliana, a gene called FLC produces a chemical that stops its little white blooms from opening. However, when the plant is exposed to a long winter, the by-products of other genes measure the length of time it has been cold, and close down or repress the FLC in an increasing number of cells as the cold persists. When spring comes and the days start to lengthen, the plant, primed by the cold to have low FLC, can now flower. But to be effective, the anti-FLC mechanism needs an extended chilly spell, rather than shorter periods of fluctuating temperatures.

This involves what's called epigenetic memory. Even after vernalised plants are returned to warm conditions, FLC is kept low via the remodelling of what are called chromatin marks. These are proteins and small chemical groups that attach to DNA within cells and influence gene activity. Chromatin remodelling can even be transmitted to subsequent generations of divided cells, such that these later produced cells 'remember' past winters. If the cold period has been long enough, plants with some cells that never went through a cold period can still flower in spring, because the chromatin modification continues to inhibit the action of FLC.

But is this really memory? Plant scientists who study 'epigenetic memory' will be the first to admit that it's fundamentally different from the sort of thing studied by cognitive scientists. Is this use of language just metaphorical shorthand, bridging the gap between the familiar world of memory and the unfamiliar domain of epigenetics? Or do the similarities between cellular changes and organism-level memories reveal something deeper about what memory really is?

Both epigenetic and 'brainy' memories have one thing in common: a persistent change in the behaviour or state of a system, caused by an environmental stimulus that's no longer present. Yet this description seems too broad, since it would also capture processes such as tissue damage, wounding or metabolic changes. Perhaps the interesting question isn't really whether or not memories are needed for cognition, but rather which types of memories indicate the existence of underlying cognitive processes, and whether these processes exist in plants. In other words, rather than looking at 'memory' itself, it might be better to examine the more foundational question of how memories are acquired, formed or learned.

When the plant was dropped from a height, it learned that this was harmless and didn't demand a folding response

'The plants remember,' said the behavioural ecologist Monica Gagliano in a recent radio interview, 'they know exactly what's going on.' Gagliano is a researcher at the University of Western Australia, who studies plants by applying behavioural learning techniques developed for animals. She reasons that if plants can produce the results that lead us to believe other organisms can learn and remember, we should similarly conclude that plants share these cognitive capacities. One form of learning that's been studied extensively is habituation, in which creatures exposed to an unexpected but harmless stimulus (a noise, a flash of light) will have a cautionary response that slowly diminishes over time. Think of entering a room with a humming refrigerator: it's initially annoying, but usually you'll get used to it and perhaps not even notice after a while. True habituation is stimulus-specific, so with the introduction of a different and potentially dangerous stimulus, the animal will be re-triggered. Even in a humming room, you will probably startle at the sound of a loud bang. This is called dishabituation, and distinguishes genuine learning from other kinds of change, such as fatigue.

In 2014, Gagliano and her colleagues tested the learning capacities of a little plant called Mimosa pudica, a creeping annual also known as touch-me-not. Its name comes from the way its leaves snap shut defensively in response to a threat. When Gagliano and her colleagues dropped M pudica from a height (something the plant would never have encountered in its evolutionary history), the plants learned that this was harmless and didn't demand a folding response. However, they maintained responsiveness when shaken suddenly. Moreover, the researchers found that M pudica's habitation was also context-sensitive. The plants learnt faster in low-lit environments, where it was more costly to close their leaves because of the scarcity of light and the attendant need to conserve energy. (Gagliano's research group was not the first to apply behavioural learning approaches to plants such as M pudica, but earlier studies were not always well-controlled so findings were inconsistent.)

But what about more complex learning? Most animals are also capable of conditioned or associative learning, in which they figure out that two stimuli tend to go hand in hand. This is what allows you to train your dog to come when you whistle, since the dog comes to associate that behaviour with treats or affection. In another study, published in 2016, Gagliano and colleagues tested whether Pisum sativum, or the garden pea, could link the movement of air with the availability of light. They placed seedlings at the base of a Y-maze, to be buffeted by air coming from only one of the forks - the brighter one. The plants were then allowed to grow into either fork of the Y-maze, to test whether they had learned the association. The results were positive - showing that the plants learned the conditioned response in a situationally relevant manner.

The evidence is mounting that plants share some of the treasured learning capacities of animals. Why has it taken so long to figure this out? We can start to understand the causes by running a little experiment. Take a look at this image. What does it depict?

Most people will respond either by naming the general class of animals present ('dinosaurs') and what they are doing ('fighting', 'jumping'), or if they are dinosaur fans, by identifying the specific animals ('genus Dryptosaurus '). Rarely will the mosses, grasses, shrubs and trees in the picture get a mention - at most they might be referred to as the background or setting to the main event, which comprises the animals present 'in a field'.

In 1999, the biology educators James Wandersee and Elisabeth Schussler called this phenomenon plant blindness - a tendency to overlook plant capacities, behaviour and the unique and active environmental roles that they play. We treat them as part of the background, not as active agents in an ecosystem.

Some reasons for plant blindness are historical - philosophical hangovers from long-dismantled paradigms that continue to infect our thinking about the natural world. Many researchers still write under the influence of Aristotle's influential notion of the scala naturae, a ladder of life, with plants at the bottom of the hierarchy of capacity and value, and Man at the peak. Aristotle emphasised the fundamental conceptual divide between immobile, insensitive plant life, and the active, sensory realm of animals. For him, the divide between animals and humankind was just as stark; he didn't think animals thought, in any meaningful way. After the reintroduction of such ideas into Western European education in the early 1200s and throughout the Renaissance, Aristotelean thinking has remained remarkably persistent.

It's often adaptive for humans to treat plants as object-like, or simply filter them out

Today, we might call this systematic bias against non-animals zoochauvinism. It's well-documented in the education system, in biology textbooks, in publication trends, and media representation. Furthermore, children growing up in cities tend to lack exposure to plants through interactive observation, plant care, and a situated plant appreciation and knowledge by acquaintance.

Particularities of the way our bodies work - our perceptual, attentional and cognitive systems - contribute to plant blindness and biases. Plants don't usually jump out at us suddenly, present an imminent threat, or behave in ways that obviously impact upon us. Empirical findings show that they aren't detected as often as animals, they don't capture our attention as quickly, and we forget them more readily than animals. It's often adaptive to treat them as object-like, or simply filter them out. Furthermore, plant behaviour frequently involves chemical and structural changes that are simply too small, too fast or too slow for us to perceive without equipment.

As we are animals ourselves, it's also easier for us to recognise animal-like behaviour as behaviour. Recent findings in robotics indicate that human participants are more likely to attribute properties such as emotion, intentionality and behaviour to systems when those systems conform to animal or human-like behaviour. It seems that, when we're deciding whether to interpret behaviour as intelligent, we rely on anthropomorphic prototypes. This helps to explain our intuitive reluctance to attribute cognitive capacities to plants.

But perhaps prejudice is not the only reason that plant cognition has been dismissed. Some theorists worry that concepts such as 'plant memory' are nothing but obfuscating metaphors. When we try to apply cognitive theory to plants in a less vague way, they say, it seems that plants are doing something quite unlike animals. Plant mechanisms are complex and fascinating, they agree, but not cognitive. There's a concern that we're defining memory so broadly as to be meaningless, or that things such as habituation are not, in themselves, cognitive mechanisms.

One way of probing the meaning of cognition is to consider whether a system trades in representations. Generally, representations are states that are about other things, and can stand in for those things. A set of coloured lines can form a picture representing a cat, as does the word 'cat' on this page. States of the brain are also generally taken to represent parts of our environment, and so to enable us to navigate the world around us. When things go awry with our representations, we might represent things that aren't there at all, such as when we hallucinate. Less drastically, sometimes we get things slightly wrong, or misrepresent, parts of the world. I might mishear lyrics in amusing ways (sometimes called 'mondegreens'), or startle violently thinking that a spider is crawling on my arm, when it's only a fly. The capacity to get it wrong in this way, to misrepresent something, is a good indication that a system is using information-laden representations to navigate the world; that is, that it's a cognitive system.

When we create memories, arguably we retain of some of this represented information for later use 'offline'. The philosopher Francisco Calvo Garzón at the University of Murcia in Spain has argued that, for a physical state or mechanism to be representational, it must 'stand for things or events that are temporarily unavailable'. The capacity for representations to stand in for something that's not there, he claims, is the reason that memory is taken to be the mark of cognition. Unless it can operate offline, a state or mechanism is not genuinely cognitive.

The mallow learns a new location when plant physiologists mess with its 'head' by changing the light's direction

On the other hand, some theorists allow that certain representations can only operate 'online' - that is, they represent and track parts of the environment in real time. The mallow's nocturnal capacity to predict where the Sun will rise, before it even appears, seems to involve 'offline' representations; other heliotropic plants, which track the Sun only while it is moving across the sky, arguably involve a kind of 'online' representation. Organisms that use only such online representation, theorists say, might still be cognitive. But offline processes and memory provide stronger evidence that organisms are not just responding reflexively to their immediate environment. This is particularly important for establishing claims about organisms that we are not intuitively inclined to think are cognitive - such as plants.

Is there evidence that plants do represent and store information about their environment for later use? During the day, the mallow uses motor tissue at the base of its stalks to turn its leaves towards the Sun, a process that's actively controlled by changes in water pressure inside the plant (called turgor). The magnitude and direction of the sunlight is encoded in light-sensitive tissue, spread over the mallow's geometric arrangement of leaf veins, and stored overnight. The plant also tracks information about the cycle of day and night via its internal circadian clocks, which are sensitive to environmental cues that signal dawn and dusk.

Overnight, using information from all these sources, the mallow can predict where and when the Sun will rise the next day. It might not have concepts such as 'the Sun' or 'sunrise', but it stores information about the light vector and day/night cycles that allows it to reorient its leaves before dawn so that their surfaces face the Sun as it climbs in the sky. This also allows it to re-learn a new location when plant physiologists mess with its 'head' by changing the direction of the light source. When the plants are shut in the dark, the anticipatory mechanism also works offline for a few days. Like other foraging strategies, this is about optimising available resources - in this case, sunlight.

Does this mechanism count as a 'representation' - standing in for parts of the world that are relevant to the plant's behaviour? Yes, in my view. Just as neuroscientists try to uncover the mechanisms in nervous systems in order to understand the operation of memory in animals, plant research is beginning to unravel the memory substrates that allow plants to store and access information, and use that memory to guide behaviour.

Plants are a diverse and flexible group of organisms whose extraordinary capacities we are only just beginning to understand. Once we expand the vista of our curiosity beyond animal and even plant kingdoms - to look at fungi, bacteria, protozoa - we might be surprised to find that many of these organisms share many of the same basic behavioural strategies and principles as us, including the capacity for kinds of learning and memory.

To make effective progress, we need to pay careful attention to plant mechanisms. We need to be clear about when, how and why we are using metaphor. We need to be precise about our theoretical claims. And where the evidence points in a direction, even when it is away from common consensus, we need to boldly follow where it leads. These research programmes are still in their infancy, but they will no doubt continue to lead to new discoveries that challenge and expand human perspectives on plants, blurring some of the traditional boundaries that separated the plant and animal realms.

Of course, it's a stretch of the imagination to try to think about what thinking might even mean for these organisms, lacking as they do the brain(mind)/body(motor) divide. However, by pushing ourselves, we might end up expanding the concepts - such as 'memory', 'learning' and 'thought' - that initially motivated our enquiry. Having done so, we see that in many cases, talk of plant learning and memory is not just metaphorical, but also matter-of-fact. Next time you stumble upon a kerbside mallow bobbing in the sunlight, take a moment to look at it with new eyes, and to appreciate the window this little weed provides into the extraordinary cognitive capacities of plants.

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Beyond the animal brain: plants have cognitive capacities too - Laura Ruggles | Aeon Essays

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At first glance, the Cornish mallow ( Lavatera cretica) is little more than an unprepossessing weed. It has pinkish flowers and broad, flat leaves that track sunlight throughout the day. However, it's what the mallow does at night that has propelled this humble plant into the scientific spotlight.

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BBC How Plants Communicate & Think - Amazing Nature Documentary

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Index of articles

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Read writing from Daniel Christian Wahl on Medium. Catalyzing transformative innovation in the face of converging crises, advising on regenerative whole systems design. Author of Designing Regenerative Cultures.

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Extinct Tree Brought Back to Life from 2000-Year-Old Seeds Archaeologists Found in a Clay Jar

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Extinct Tree Brought Back to Life from 2000-Year-Old Seeds Archaeologists Found in a Clay Jar

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Male Judean date palm germinated and grown from seeds in a museum

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According to legend, the ancient Judean date palm was the tree whose fronds made way for Jesus and his donkey on Palm Sunday and the tree King David named his daughter after

The Judean date palm flourished throughout the Middle East for thousands of years before the Romans conquered Jerusalem around 70 AD.

The fruit of the trees - dates - served as a staple food in the region, while its leaves provided shelter and shade. A symbol of fertility, the tree was used as an aphrodisiac and cherished for its medicinal properties.

According to the Old Testament of the Bible, King David named his daughter after the Hebrew word for the tree - Tamar - and according to the New Testament, Jesus followers' laid date palm leaves at his feet when he and his donkey came riding into Jerusalem.

Likely because the trees were so central to the Judean economy, the Romans wiped them out. By 500 AD, they were extinct.

Luckily, someone preserved a batch of the tree's seeds in a clay jar just before they completely disappeared.

Archaeologists found the jar in the ruins of Herod the Great's palace in the 1960s.

Carbon dating revealed the seeds to be about 2000 years old, the last living vestiges of the long lost Kingdom of Judah... yes, living.

After sitting in a dusty university drawer for decades, an archaeologist challenged a botanist to do the unthinkable - germinate them.

"You want me to do what?" desert agriculture expert Elaine Solowey said when she was first propositioned.

"I assumed the food in the seed would be no good after all that time. How could it be?" she told National Geographic.

But she gave it a go.

She soaked the seeds in hot water and then in a solution of nutrients and enzymatic fertilizer. She planted them in pots in January of 2005, and sure enough, by March, one sprouted, becoming the oldest known tree seed to germinate.

"I couldn't believe it," Solowey said.

Today, the tree continues to grow and thrive. As of 2015, it was 10 feet tall, growing flowers and making good pollen.

The tree is a male tree, unable to produce fruit, so now researchers are working on sprouting a female from the same batch of seeds, so Methuselah (as he's been dubbed) can pollinate her.

Solowey has already tested his pollen on a modern variety of a female date tree, and confirmed that "yeah, he can make dates."

If she succeeds at germinating an ancient female date palm, she notes, "we would know what kind of dates they ate in those days and what they were like. That would be very exciting."

Genetic tests indicate that Methuselah is most closely related to an ancient variety of date palm from Egypt, which fits with a legend that says dates came to Israel with the children of the Exodus, Solowey says.

She hopes to establish an orchard of ancient dates, so she and colleagues can study the plants to see if they have any unique medicinal properties.

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Extinct Tree Brought Back to Life from 2000-Year-Old Seeds Archaeologists Found in a Clay Jar

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According to legend, the ancient Judean date palm was the tree whose fronds made way for Jesus and his donkey on Palm Sunday and the tree King David named his daughter after The Judean date palm flourished throughout the Middle East for thousands of years before the Romans conquered Jerusalem ...

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We Are Not Alone: What Animals Think and Feel

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We Are Not Alone: What Animals Think and Feel

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Carl Safina, ecologist, author and expert on animal consciousness, reveals that many non-human minds are far more similar to ours than previously thought

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Carl Safina - We Are Not Alone: What Animals Think and Feel | Bioneers 2017

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Mountain ash forests in the Victorian Central Highlands

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A philosophy of participation in dynamic wholeness

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A philosophy of participation in dynamic wholeness

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Excerpt from Daniel Christian Wahl's 2002 masters dissertation in Holistic Science at Schumacher College

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Excerpt from Exploring Participation (D.C.Wahl 2002)

[Note: This is an excerpt from my 2002 masters dissertation in Holistic Science at Schumacher College. It addresses some of the root causes of our current crises of unsustainability and applied insights from holistic science to ecological design. This excerpt explores the fundamentals of what Charles Eisenstein later (2014) referred to as 'the story of separation' and 'the story of interbeing. Be warned, this is academic, somewhat dense writing, yet it addresses some crucial issues. Enjoy!]

"Our task is to look at the world and see it whole."

- E.F. Schumacher

"The success or failure of saying, and hence of writing, turns upon the ability to recognize what is part and what is not. But a part is a part only inasmuch as it serves to let the whole come forth, which is to let meaning emerge. A part is only a part according to the emergence of the whole which it serves; otherwise it is mere noise. At the same time, the whole does not dominate, for the whole cannot emerge without the parts. The hazard of emergence is such that the whole depends on the parts to be able to come forth, and the parts depend on the coming forth of the whole to be significant instead of superficial."

- Henri Bortoft

The above remains meaningful whether we understand it hermeneutically, as referring to a text and the reciprocity of meaning between the whole and the parts, as well as understood as an analogy for our individual relationship to the wider whole - the world we live in.

In order to continue to emerge in good health, a whole like our living planet depends on the appropriate participation of its parts, and that includes humanity. Just as the parts - you and me - depend on the emergence of this healthy whole for their meaningful and healthy existence.

In this dissertation, I aim to convey some of the understanding that recognizes the intricate link between the health of the whole and the appropriate participation of the parts. I argue that appropriate participation takes place on the appropriate spatial-temporal scales and that the complex dynamic processes of life, which are continuously transforming the whole, depend on an intricate web of relationships through which everything and everybody participate simultaneously as the weavers and as the web of life.

Each individual part of this dissertation is intended to let meaning emerge and let the whole come forth. "Logic is analytical, whereas meaning is evidently holistic, and hence understanding can not be reduced to logic. We understand meaning in the moment of coalescence when the whole is reflected in the parts so that they disclose the whole."10 The circle of relationship between the whole and the parts, in which meaning emerges, was first recognized by Friedrich Ast, who called it the hermeneutical circle.

I argue, based on my interpretation of Bortoft's work, that the same circle of relationships between the whole and the part that is expressed in the hermeneutical circle of understanding meaning, may also help to understand our own reciprocally co-creative relationship between our perceived selves and the world we thus perceive.

It is the whole-part relation that manifests in creation, maintenance and transformation of the identities, which in turn manifest as the world we experience. At the core of this re-emergence of meaning, at the foundations of a newly emerging worldview is the awareness of our deeply participatory relationship with the living world.

In the same way that the parts and the whole of this dissertation bring forth each other, mutually dependent on each other for their meaningful existence, each one of us derives meaningful existence through his or her profoundly reciprocal relationships and interactions with the world.

Paying attention to the participatory nature of all existence and our associated creative agency in the world can help us to overcome the alienation and lack of meaning, which characterizes the modern world.

Whether we are conscious of it or not, each one of us is constantly engaged in a creative process through which we collectively bring forth or contribute to the emergence of the whole. Yet, the whole in its entirety has neither beginning nor end and there is no possibility of being outside the whole. Therefore, it is important to understand that the interactions and relationships of its parts continuously transform the whole from within, allowing for creative change to occur and new interpretations of meaning as well as new manifestations of the whole to emerge.

In other words, we need to face up to responsibility for our actions. Whatever we do is shaping the world we live in, while we are simultaneously being shaped by the world we collectively co-create through our thoughts, words and actions. The whole and the part create each other and it may serve us better to think of them not as separate and exclusive, but rather as mutually dependent and encompassing, reciprocating entities that co-create the world in a continuous process of interacting with and relating to each other. The whole and the part, as well as the observer and the observed are truly one, as well as being distinct within that one whole.

A participant-observer understanding of the world as a whole can lead us to seeing how the one can express itself as the many in the diversity of manifestations that emerge through the interactions and relationships of all participant-observers.

The process is analogous to how the one meaning of this dissertation expresses itself through the different interpretations of each individual reader. There is only one meaning and one whole, but it manifests itself differently through the ever-shifting web of relationships of its participant- observers. Like the one universal whole, meaning should not be thought of as fixed or static, but as a dynamic process un/en-folding through relationship, direct sensory experience and interpretation.

Seen in this way, diversity is no longer the threatening, challenging existence of many others competing with our self, but rather the breathtakingly beautiful and meaningful expression of a limitless variety of manifestations that the same one, which we are of, can take as we experience relationship.

We are all of the same one, yet we are the same one differently, so we can learn to begin to cherish diversity as the true expression of our unity with the world. We are not all the same, but we are one. In loosing diversity, we loose ways of experiencing our own individuality and ultimately we loose a part of ourselves.

This understanding of the relationships between the whole and its parts, between each one of us individually and the world or the universe as a whole can help us to find language to express our fundamental interconnectedness with the living world.

We are who we are only in relationship to all there is. The world as we know it emerges in a process of reciprocal co-creation that integrates us inseparably into the world we experience. In other words, as David Abram has put it so beautifully:

"Caught up in a mass of abstractions, our attention hypnotized by a host of human-made technologies that only reflect us back to ourselves, it is all too easy for us to forget our carnal inherence in a more- than-human matrix of sensations and sensibilities. Our bodies have formed themselves in delicate reciprocity with the manifold textures, sounds, and shapes of an animate earth - our eyes have evolved in subtle interaction with other eyes, as our ears are attuned by their very structure to the howling of the wolves and the honking of the geese. To shut ourselves off from these other voices, to continue by our lifestyles to condemn these other sensibilities to the oblivion of extinction, is to rob our own senses of their integrity, and to rob our minds of their coherence. We are human only in contact, and conviviality, with what is not human."11 - David Abram

In the Santiago theory of cognition Humberto Maturana and Francisco Varela proposed that the process through which an individual interacts with its environment is fundamentally a cognitive process. This process of cognition, of structural coupling between the organism and its environment, is regarded as the fundamental process of life itself. In our reflective consciousness this process emerges as the process of knowing.

Maturnana and Varela emphasize that, as we are beginning to understand how we know, we have to realize "that the world everyone sees is not the world but a world which we bring forth with others" and "that the world will be different only if we live differently."12 I would like to add that every time we bring forth a world, it also is the world manifesting itself in a particular way.

We will have to find new ways of expressing that we are living in a fundamentally paradoxical universe. While our individual experience of our embodied self is real and allows us, through our senses and the concepts we form, to enter into relationships with a real world, we paradoxically also are the world we thus perceive as it emerges out of our relationship with it.

A truly participatory understanding recognizes that a participating part can never be separate from the whole it participates in. It is always both part and whole simultaneously. This new dynamical way of thinking is "recovering a way of thinking based on living in the movement of paradox rather than eliminating it." The dynamical way of thinking places paradox "at the very core of understanding."13

The universe as the one unique whole can never be fully understood in the way that modern Reductionist science aims to understand the world through logical reasoning, prediction and control. Why? Simply because, it is not possible to take an outsider or objective point of view of the whole in its entirety.

The whole can only be approached by taking partial reference from within. This makes the observer of the whole inevitably a participant in it and blurs subject object distinctions. In observing the whole the observer will have to include him or herself, both as the observing subject as well as the observed object.

To be subject and object simultaneously fundamentally conflicts with logical reasoning dependent on either/or choices. We encounter the paradox. Reductionist science is based on the either/or logic of a Cartesian subject-object dichotomy.

Curiously, despite Werner Heisenberg's famous reminder to the scientific community, that "what we observe is not nature itself, but nature exposed to our method of questioning" and his caution that every act of observation has its associated observational blind-spot, most of science today is still based on dualistic reasoning, that draws sharp either/or distinctions between subject and object and between the observer and the observed.

Based on Aristotle's, often disregarded or misinterpreted, self actualisation thesis, which metaphorically explained equates the process of the builder building with the process of the building being built, Henri Bortoft points out that this way of experiencing an event as process constitutes "an intermediary philosophical position between monism and dualism." In what Bortoft calls "a unitary event" one is not reduced to the other. It is not a "monistic event".14 Neither are there two events. Dualism sees the builder as the subject and the building as the object being built and the process of building-a-building-a-building-being-built as two distinct processes.

I believe Aristotle's focus here is on the process of reciprocal co-creation and the emergence of identity out of relationship and interaction in this unitary event. Building the building makes the builder a builder, while being built by the builder, makes the building a building. The individual identities emerge out of, or manifest themselves through the relationships established by one single process.

Understanding process in this way lets us experience the coming into being of individual identity through relationship. Rather than experiencing a static world of finished products preconceived by viewing with subject-object goggles from the start, we being to see and think more dynamically thus experiencing reciprocal co-creation of the diversity of identities through relationship.

It is important to realize how deeply the Cartesian subject-object separation is affecting the way we interpret the world and our experiences within it. Especially with regard to the conceptual framework that makes the world appear to us as it does. Bortoft, extending Gadamer's work on hermeneutics shows that "meaning is understanding"15 and that it is precisely the Cartesian subject-object presupposition that stops us from understanding how meaningful this insight is.

Maybe this is also why the Reductionist universe we constructed based on the subject-object presupposition seems so devoid of meaning? Our purely rational understanding of the objectified world lacks the deeper meaning which arises in the participatory experience of true, embodied understanding as an expression of a conscious universe.

Just as there are sheer infinite possibilities to interpret meaning, there are infinite possibilities of the universe manifesting itself in a diversity of identities. In both cases, interpretation or manifestation depends on the relation between the part and the whole.

Seen from this perspective one could venture to say: the meaning of life is living in relation to the whole that enfolds us, participating meaningfully in its unfolding. To understand this be aware that neither life, nor mind, nor meaning, nor language, nor the universe are things, they are processes reflecting one single process: the whole un/en-folding in relation with and through the parts

As we begin to realize our fundamentally participatory relationship with this process of the whole un/en-folding, as we direct our attention toward our co-creative potential as consciously participating agents in the expression of individual identity and in the interpretation of meaning, life becomes profoundly meaningful. Meaning and life unfold together.

We can relate to this unfolding through our sensory experience, intuitive perception, as well as through our language and all other forms of communication. Since we are enfolded in the whole, we are participants by nature and always in relation. Seen from this perspective, our relationships are us.

Who we are is continuously being defined by the relationships that give us identity. Life and meaning are processes of expression and interpretation of the whole through its parts. We are participating parts of this process, therefore, as Brian Goodwin once told me:

"The point is not to understand the meaning of life, but to live a life of meaning." - Prof. Brian Goodwin

I believe that living a life of meaning is about paying attention to our relationship to the community of life in its entirety. It is about appropriate participation in the process of life - participation in meaning unfolding.

Life is a universe of meaning unfolding through relationship. Or, as Thomas Berry has put it: "The universe is not a collection of objects, but a communion of subjects."16 Meaning is not something we need to search for or that we may encounter at some time in the future. The only place that meaning can unfold is in our relation to the living present - in the relations we participate in from day to day.

"The notion of the living present is one in which the future, as expectation and anticipation, is in the detail of actual interactions [relation] taking place now, as is the past as reconstructions in this process of memory. There is no dismissing the past or the future here, nor is there any distraction from the present of what we are doing together."17

Seen this way, the universe is a continuous and diverse interpretation of meaning, in the living present, life manifesting as the diversity of expressions of individual identity through relationship. The universe is the whole coming forth into and through its parts. Bortoft argues:

"There is only one meaning. It is the one meaning that can manifest itself in different forms and therefore there is difference within meaning. The differences are elicited by the different cultural and historical contexts and personal situations [read relation], which that meaning appears in ... no matter how many times the work is understood it is always the one meaning ... coming into being in the happening of understanding." 18 - Henri Bortoft

Bortoft refers to the "one that appears as the many", as the "intensive dimension of one". He emphasizes that the diversity of interpretations of the work (whole) do not fragment it, because what we see as diversity is in fact dynamical living unity. Just like Maturana and Varela proposed to equate the process of cognition with the process of life and, in the reflective consciousness of humans, with the process of knowing, Bortoft shows that meaning is akin to life. Like Goethe and Gadamer before him, he takes the position that meaning is inexhaustible, but neither predetermined nor indeterminate. Meaning in Gadamer's hermeneutics is rather like Goethe described the world:

"She is complete but ever unfinished". - Goethe

Bortoft shows clearly that the world is not an object, but a process. We participate in a world that is complete but unfinished. The way that meaning continuously manifests itself through the diversity of its interpretations reflects the way the world continuously manifests as a "dynamical unity producing itself in different modes according to language." What is important to understand here, as Bortoft emphasized, is that experiencing the world in this way "is not perspectivism. It is manifestationism."19 Each interpretation is a manifestation of the whole, each experience of the world is the world.

Language and all other forms of communication are ways of entering into relation and thus participation in the whole. Sensory experience is fundamental for entering into relation with the world. Just as described by Aristotle's self-actualization thesis, where the event of building manifests the identities of the builder and the building, in the event of perception the identities of the perceiver and the perceived manifest.

Through the same reciprocally co-creative relationship of the whole and the part, described above, the identities of the perceiver and of the perceived manifest within the web of relationships that connects them to each other and the whole. It is through relationship that we bring forth a world.

In his book The Spell of the Sensuous, David Abram explores our relationship as sensing, embodied beings with the living world we participate in. He points out that in the event of perception as it is experienced "neither the perceiver nor the perceived are wholly passive.... To the sensing body no thing presents itself as utterly passive or inert."20

Experientially considered the world is a living presence to us; distinctions like animate and inanimate, active and passive arise when we interpret experience conceptually.

Entering into relation, including all forms of communication, transform the web of relationships, thereby changing (causing, defining or terminating) individual identities, their physical manifestation as well as an identity's particular way of interpreting meaning or manifesting the whole.

Interpreting Merleau-Ponty, David Abram writes: "Experientially considered, language is no more the special property of the human organism than it is expression of the animate earth that enfolds us."21 He points out that:

"Communicative meaning is always, in its depths, affective; it remains rooted in the sensual dimension of experience, born of the body's native capacity to resonate with other bodies and with the landscape as a whole. Linguistic meaning is not some ideal and bodiless essence that we arbitrarily assign to physical sound or word and then toss out into the external world. Rather meaning sprouts in the very depth of the sensory world, in the heat of meeting, encounter, participation."22 - David Abram

Yet another very important mental construct that influences the way we see the world fundamentally is our understanding of time and space. As three prominent phenomenologists, Husserl, Merleau-Ponty and Heidegger, have concluded independently, in direct pre-conceptual experience it is impossible to distinguish time and space.23 Our understanding of time and space is really at the heart of it all, but it would go beyond the bounds of this dissertation to mention more than the most fundamental points.

The philosopher and Zen master David Loy points out that "the objectification of time is also the subjectification of the self, which thus appears only to discover itself in the anxious position of being a nontemporal entity inextricably trapped in time."24

In other words the idea of self as something permanent and unchanging, as a thing and not a process of changing identity in relation, creates linear time as separate from space.

Indigenous, oral cultures, living by the cycles of day and night, the moon and the seasons, perceive time as cyclical. "Unlike linear time, time conceived as cyclical cannot be readily abstracted from the spatial phenomena that exemplify it - from, for instance, the circular trajectories of the sun, the moon, and the stars. Unlike a straight line, a circle demarcates and encloses a spatial field."25

Our visible experiential space, as David Abram points out, is also demarcated by a circle - the horizon. He concludes: "Thus cyclical time, the experiential time of an oral culture, has the same shape as perceivable space. And the two circles are in truth one."26 Our predominant understanding of linear space and time is yet another example of rigid either/or thinking. David Abram believes:

"The conceptual separation of time and space - the literate distinction between a linear, progressive time and a homogenous, featureless space - function to eclipse the enveloping earth from human awareness. As long as we structure our lives according to assumed parameters of static space and a rectilinear time, we will be able to ignore, or overlook, our thorough dependence upon the earth around us. Only when space and time are reconciled into a single, unified field of phenomena does the encompassing earth become evident, once again, in all its power and its depth, as the very ground and horizon of all our knowing."27 - David Abram

I would like to stress the fundamental importance of direct sensory experience as the primary mode of entering into relationship and knowing the world. Although, as human beings, we predominantly live in a world that manifests itself through language and the mental concepts we express, nevertheless language can only remain meaningful if it reflects our embodied, sensory experience of the world and allows us to express the direct, intuitive understanding of that world-whole, as it is reflected in us - the world-part - through direct experience. David Abram reminds us that:

"Language is ... an evolving medium we collectively inhabit, a vast topological matrix in which speaking bodies are generative sites, vortices where the matrix itself is continually being spun out of the silence of sensorial experience...Merleau-Ponty comes in his final writings to affirm that it is first the sensuous, perceptual world that is relational and web-like in character, and hence that the organic, interconnected structure of any language is an extension or echo of the deeply interconnected matrix of sensorial reality itself. Ultimately, it is not human language that is primary, but rather the sensuous, perceptual life-world, whose wild, participatory logic ramifies and elaborates itself in language."28 - David Abram

The distrust of the senses arose out of Descartes' cogito ergo sum and is an expression of the resulting mind-body dualism. It has critically influenced Reductionist science, our culture and the way we experience the world. Phenomenologists, like Merleau- Ponty, do not follow the tradition of Reductionist science attempting to explain the world objectively, but aim to describe "as closely as possible the way the world makes itself evident to awareness, the way things arise in our direct sensorial experience."29

By accepting one way of seeing and interpreting, that of Reductionist science and its dualistic perspective, as the only way of seeing, we have become epistemologically rigid. Not only have we locked ourselves into our bodies, through a rigidly adhered to, either/or - type, boundary between the self and the world, between subject and object. We have retreated even further in denying our own subjective sensory experience as a legitimate way of entering into relation and understanding (presence-ing meaning in) the world.

Our reduced sense of self is hiding out in our minds, busily re-enforcing the alienating prison of a mentally constructed objective reality that isolates us from the world of qualities and meaning in which we actually live and experience.

By asserting that only the measurable and quantifiable is real and doubting our own sensory, embodied experience of the world we have fallen victim to yet another rigid dualism - the separation of mind and body.

This same dualism finds expression in separating mind and matter, as well as energy and matter. Yet boundaries are never as rigid as they appear when viewed from within the dualist mindset. Seen more dynamically, nothing purely excludes its dualist opposite in the process of un/en-folding by which the whole transforms, as it manifests itself in diversity.

What one way of seeing labels as opposites, in another, more dynamical way of seeing, merely reflects the relationship of the whole and the part. Each one containing the other, but not as two, rather as potential manifestations of the one unity, depending on the complete but ever unfinished web of relationships through which temporary identities manifest and express themselves. Let me briefly exemplify the dissolution of these rigid either/or boundaries taking place in the history of science. I will dedicate more attention to this in the next chapter.

Almost one hundred years ago, quantum mechanics and the understanding of quantum entanglement provided a scientific basis for accepting the fundamental interconnectedness of all matter and relativity theory established how mass and energy can transform into each other ( Einstein's famous e = mc2).

With regard to the split between mind and matter, Fritjof Capra believes that the Santiago theory of cognition is the first scientific theory that overcomes this division. He explains that by regarding mind not as a thing but as a process - the process of cognition - and by identifying this process as the process of life, "mind and matter no longer appear to belong to two separate categories, but can be seen as representing two complementary aspects of the phenomenon of life..."30

What is important to realize here is that "we are accustomed to thinking of mind as if it were inside us - 'in our heads'. But it is the other way around. We live within a dimension of mind which is, for the most part, as invisible to us as the air we breathe."31 There is no rigid, either/or boundary between mind and matter, or as David Abram put it:

"Clearly, a wholly immaterial mind could neither see nor touch things - indeed, could not experience anything at all. We can experience things - can touch, hear, and taste things - only because, as bodies, we are ourselves included in the sensible field, and have our own texture, sounds, and tastes. We can perceive things at all only because we ourselves are entirely a part of the sensible world that we perceive! We might as well say that we are organs of this world, flesh of its flesh, and that the world is perceiving itself through us."32 - David Abram

In the predominant, dualistic way of seeing, "we consider knowledge to be a subjective state of the knower, a modification of consciousness which in no way affects the phenomenon that is known", which we regard to be the same "whether it is known or not." The dynamical way of seeing, regards the knower not as "an onlooker but a participant in nature's processes, which now act in consciousness to produce the phenomenon consciously as they act externally to produce it materially."33

As participants in the complex and dynamic processes of nature, as parts reflecting the whole, we are transformed by and transform the world through our way of knowing, which expresses and guides our way of participating.

What we have to realize here is that what we become aware of, depends on the sensory and on the non-sensory aspect to cognitive perception. While it is our direct, embodied, sensory experience that allows us to enter into relationship with the world in the first place, our way of seeing, the organizing ideas we employ, shape what we become aware of and thus the world we bring forth. This has profound implications as it can help us to understand that "all scientific knowledge ...is a correlation of what is seen with the way it is seen."34

One of the most promising and daring attempts to provide a philosophical framework to integrate most of what I have discussed above was recently provided by the philosopher Christian de Quincey in his book Radical Nature - Rediscovering the Soul of Matter.

De Qunicey offers both a new ontological basis, as well as a new epistemology, which complements the relation-focused understanding of participation in the un/en-folding of the whole, which I discussed above. As I have mentioned, I believe we live in a fundamentally paradoxical universe, since we all need to come to terms with our daily experience of subjectivity in what we otherwise describe as an objective universe.

I agree with De Quincey that rather than attempting to remove the paradox, "our task will be to move into it, and know it in a new way." He proposes a new postmodern "paradox paradigm" that "asserts the primacy of extrarational experience."35 He argues for a participatory and intersubjective epistemology - "a way of knowing that takes us into the heart of mystery, and invites the paradox of consciousness into our very being."36 De Quincey believes that:

"Epistemologically, we must engage the paradox. "Paradox" means, literally, "beyond" (para) "opinion or belief" (doxa). Paradox, then, takes us into the "space" that is beyond belief - into experience itself. Ontologically, it invites us into the ambiguity of being - an ambiguity of neither this-or that nor this-and- that, nether either/or nor both/and, but all of these together."37 - Christian De Qunicey

De Quincey calls his philosophical framework Radical Naturalism. Central to his argument is the fundamental assumption: "It is inconceivable that sentience (subjectivity; consciousness), could ever emerge or evolve from wholly insentient (objective, physical matter)." He therefore argues: "the assumption of consciousness and matter as coextensive and coeternal is the most adequate 'postmodern' solution to the question of consciousness in the physical world.

Where materialism, idealism, and dualism fall short as adequate ontologies for a science of consciousness, radical naturalism provides a coherent foundation. The central tenet of radical naturalism is that matter is intrinsically sentient - it is both subject and object.

Radical naturalism confronts head-on the essential paradox of consciousness: We exist as embodied subjects - as subjective objects or feeling matter." 38 The proposed philosophical framework acknowledges "the ontological and epistemological primacy of embodied feeling."39

De Quincey uses the ancient greek concept of entelechy to describe mind as 'a becoming of matter'. He regards mind as "neither outside nor inside of matter" but rather as "constituent of the very essence of matter - interior to its being."40

De Quincey believes that "the Cartesian error was to identify consciousness as a kind of substance, and not to recognize it as a process or as dynamic form inherent in matter itself. Mind is the self-becoming of self-organization - the self-creation - of matter. Without this matter could never produce consciousness."41 De Quincey summarizes the implications of his proposed philosophical framework as follows:

"With this new perspective we can now embrace the actuality of consciousness and meaning in a self- organising cosmos. Elements of the new story will include:

(1) complementarity rather than dualism,

(2) organicism rather than mechanism,

(3) holism complementing reductionism,

(4) interconnectedness rather than separateness,

(5) process rather than things,

(6) synchronicity as well as causality,

(7) creativity rather than certainty,

(8) participation and entanglement rather than objectivity.

But most of all, the new cosmology will emphasize

(9) that matter is inherently sentient all the way down, and

(10) that, therefore, nature, the cosmos - matter itself - is inherently and thoroughly meaningful, purposeful, and valuable in and for itself.

Nature, we must see, is sacred."42 - Christian De Quincey

It may now be more obvious why I found it necessary to set a philosophical context for this dissertation, why it is so important that we learn to employ multiple ways of seeing and to integrate the dualistic/Reductionist into a wider holistic, or non-dual context. It is important that we learn to embrace and live in the paradox. The rigid either/or logic of dualism is at the heart of our alienation from nature and the whole. It is also at the heart of the consequential environmental, social and cultural crisis. As David Loy explains:

"[In dualism] the self is understood to be the source of awareness and therefore of all meaning and value, which is to devalue the world/nature into merely that field of activity wherein the self labours to fulfil itself. ... the alienated subject feels no responsibility for the objectified other and attempts to find satisfaction through projects that usually merely increase the sense of alienation. The meaning and purpose sought can be attained only in a relationship whereby nonduality with the objectified other is re-established."43 - David Loy

The dualist distinction between the self and the world allowed for the development of a detached, Reductionist science in the first place. Bortoft argued that the existing ontological gulf between science and its object is a fundamental prerequisite of Reductionist science, as it allows for a science of measuring and experimenting, in which an "object appears to consciousness, it does not appear in consciousness."44

I would add that it is precisely this ontological gulf, which enables the moral and ethical detachment with which modern science continues to evade responsibility for its participation in bringing about the current environmental, social and economic crisis, we observe worldwide.

Only if we understand our fundamental interconnectedness as participants in the process of life, in relationship and conviviality with the community of life, only then will meaning appear.

Only as we learn to participate appropriately in the whole, at the appropriate spatio-temporal scale, will we be able to sustain our participation in the process. This is the heart of sustainability.

If we truly understand our participation in the whole we don't have to fear the future and can love the present. We will become aware of our responsibility to participate appropriately and meaningfully through focusing our attention to meaningful relation with the community of life.

Once we understand the meaning of the whole un/en-folding in relation with and through the parts, we have accomplished the task set by E.F. Schumacher at the beginning of this chapter "to look at the world and see it whole." Then, as Erwin Schroedinger put it:

"You can throw yourself flat on the ground, stretched out upon Mother Earth, with the certain conviction that you are one with her and she with you. Your are as firmly established, as invulnerable as she is, indeed a thousand times firmer and more invulnerable. As surely as she will engulf you tomorrow, so surely will she bring you forth anew to new striving and suffering. And not merely 'some day': now, today, every day she brings you forth, not once but a thousand times over. For eternally and always there is only now, one and the same now. The present is the only thing that has no end."45 - Erwin Schrödinger

[Note: This is an excerpt from my 2002 masters dissertation in Holistic Science at Schumacher College. It addresses some of the root causes of our current crises of unsustainability. If you are interested in the references you can find them here. The research I did for my masters thesis directly informed my2006 PhD thesis in ' Design for Human and Planetary Health: A Holistic/Integral Approach to Complexity and Sustainability' (2006), and after 10 years of experience as an educator, consultant, activist, and expert in whole systems design and transformative innovation, I published Designing Regenerative Cultures with Triarchy Press in May 2016.]

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A philosophy of participation in dynamic wholeness - Age of Awareness - Medium

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Note: This is an excerpt from my 2002 masters dissertation in Holistic Science at Schumacher College. It addresses some of the root causes of our current crises of unsustainability and applied insights from holistic science to ecological design. This excerpt explores the fundamentals of what Charles Eisenstein later (2014) referred to as 'the story of separation' and 'the story of interbeing.

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António Donato Nobre

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Antonio Donato Nobre: The magic of the Amazon: A river that flows invisibly all around us

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University of Alberta professor and experimental plant ecologist JC Cahill

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What Plants Talk About (Full Documentary)

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The Systems View of Life: a Unifying Vision

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The Systems View of Life: a Unifying Vision

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Fritjof Capra and Pier Luigi Luisi (2014) Santiago Theory of Cognition (though still massive anthropocentric bias in assessment of consciousness)

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Earth Talk: Fritjof Capra - The Systems View of Life

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A talk given at Schumacher College (UK), Dartington on May 7th 2014. The great challenge of our time is to build and nurture sustainable communities, designed in such a manner that their ways of life, physical structures, and technologies do not interfere with nature's inherent ability to sustain life.

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Paul Stammets - Nature and the Spirit of Goodness

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Paul Stammets - Nature and the Spirit of Goodness

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Emerging from their axial homes, fungi are beginning to be understood as nutrients to the human consciousness and ecological sustainability

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Scientists make surprise discovery of massive new forests around the world

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Scientists make surprise discovery of massive new forests around the world

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Discovery of 467 million ha of unreported forest has lent more credence to the theory that increasing levels of atmospheric CO2 are actually helping to increase global greening. (See similar article in The Conversation)

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Scientists make surprise discovery of massive new forests around the world

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Recent global analysis of the Earth's drylands has discovered 467 million hectares of unreported forested areas - or roughly seven times the size of Texas - located in drylands across the world. The discovery has lent more credence to the theory that increasing levels of man-made CO2 emissions are a...

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Mushrooms and the Mycology of Consciousness

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Mushrooms and the Mycology of Consciousness

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Paul Stamets explains the role of decaying natural woodland in the health of bees

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Mushrooms, Mycology of Consciousness - Paul Stamets, EcoFarm Conference Keynote 2017

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How Forests and Wildfires Are Critically Linked

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How Forests and Wildfires Are Critically Linked

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Diana Beresford-Kroeger on indigenous peoples' predictions of these times, controlled burning and eucalypts in California and Portugal

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I have called up Diana Beresford-Kroeger, the famed Irish botanist and bestselling author, to ask about the megafires that carpeted much of North America in dense smoke last summer.

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In British Columbia alone, wildfires released between 150 and 200 megatonnes of carbon dioxide in 2017. That's more than twice the volume created by human activities in the province.

Beresford-Kroeger, who calls herself a renegade scientist, has been studying forests all her life and is one of the world's leading experts on the many medicinal properties of trees.

Coming from a strong Celtic tradition, the 74-year-old plain speaker delivers a good dose of traditional knowledge with her science, combining data with old-fashioned wisdom.

The global forest, which keeps the atmosphere rich in oxygen and low in carbon dioxide, "forecasts our future in every breath it takes and every seed it releases into the leaf mold of the forest floor," she has written.

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On the day when I reach her to discuss the megafires that consumed parts of California, Chile, Sweden and B.C. last summer, she says she has both good and terrifying news.

But first Beresford-Kroeger tells me she has just walked into her house just south of Ottawa from her research garden, where native and endangered trees thrive, and is covered in mud.

"You should know," she begins with a laugh, "that you are talking to a dirty woman."

And then she plunges into the subject of wildfires, which burned almost 3.4 million hectares of forest last year across Canada - a nearly threefold increase over 2016.
Fires foretold
The first point Beresford-Kroeger wants to make is that the fires consuming places like California and B.C.'s Interior were foretold by Indigenous people thousands of years ago.

The Anishinaabe predicted an age of fire back in the 13th century, as did seers among the Celts, a woodland people whose alphabet was based on trees.

These prophets "could see the patterns of things in nature and could see how people were behaving," she says, and they predicted that greed or the relentless consumption of things would lead to conflagrations of enormous proportions.

White people banished fire, a natural player on the landscape, she says. But Indigenous people used fire. "They had a brainchild and architecturally changed the continent by fire."

The Woodland Cree set fires in meadows and along shorelines to produce more berries and provide more grass for game, just as the Cahokia people set fires to help nourish the nut trees that grew on the great North American savannah, which extended into present-day Toronto.

Flash fires in April and November produced ash that helped to fertilize the grasses and the forest. The ash even protected trees from fungal spores.

"And it doubled the production of fruits and nuts in the forest," says Beresford-Kroeger. The fertilizing effect of controlled burns increased certain kinds of vegetation a hundred-fold and enlarged the population of deer, elk and moose.

"That was their strategy and they knew what they were doing."

But the careful firing of parts of the continent was abandoned long ago as colonial governments demonized fire and made it their duty to pounce on any flame, a practice that has allowed many forests to grow more dense, uniform and flammable.

Human communities are now paying a price for 100 years of fire suppression as they built more homes in landscapes designed to renew themselves with pests or fire.

Other changes account for the rise and intensity of wildfires, which Beresford-Kroeger describes as nature's very own "chemical factories."

"We have drier air in the spring," she says. The dry air desiccates pollen tubes. As a result evergreens produce more oleoresins, which can fuel fires. "The more oleoresin, the greater the fire load."

Even deciduous trees make more resins in their leaves to fight being radiated in the sun as the climate gets drier and warmer.

"The trees are trying to fight climate change on their own and it makes them more dangerous," explains Beresford-Kroeger. "What has happened is that we have not paid attention to climate change and the changes around us."

The spread of invasive trees and grasses has also fanned wildfires around the globe.

In South Africa, for example, some of the region's worst wildfires ripped through commercial non-native pine plantations in 2017, killing eight people and destroying 800 buildings.

The pines provided more flammable material and burned more intensely than native bush, making the fires difficult to control.

The same folly has been repeated elsewhere including Chile and Portugal.

The eucalyptus was introduced from Australia to North America and Europe, Beresford-Kroeger notes. It's "a marvellous tree," she says.

"But when it sheds its bark, which is full of resin, it's like bombs going off everywhere. If anyone throws a cigarette out of a car, you can expect a bomb-like situation," explains the botanist.

That very situation killed people in California wildfires in the 1990s and during Portugal's deadliest-ever wildfire last year.

The Portugal inferno, which largely raged through eucalyptus plantations, roasted more than 60 fleeing citizens in their cars.

Portugal, one of the most heavily forested countries in Europe, used to be carpeted with native cork oak and laurel trees, which are largely resistant to fire.

But in recent years the pulp industry took advantage of dying farming communities and encouraged eucalyptus plantations on private land to boost pulp exports.

The industry valued eucalyptus because it's one of the world's fastest-growing trees. But the tree's sap is flammable, and its burning bark can fly off and ignite a fire 100 metres away. The invasive tree also burns faster and hotter than any oak or laurel.

"We are contributing to climate change by planting these trees," says Beresford-Kroeger.
Cracking branches become kindling
Another curious thing is happening in the boreal forest. Because of changes in precipitation patterns brought about by climate change there have been more ice and wet snowstorms in the great forest.

"The greenhouse effect combined with a loss of forests is adding extra moisture to the atmosphere," says Beresford-Kroeger.

For many forests that means more ice, torrential rains or heavy snow in the spring and fall.

"The trees have socket joints and the heavy snow knocks off the branches just at the socket," says the scientist. "The branches just add more fuel to the fire. That will be a problem in the north in the boreal."

Calgary, for example, had an early snowstorm in September three years ago before the city's deciduous trees had even shed their leaves.

All night, citizens could hear the cracking of branches as tons of biomass from tens of thousands of spruce trees and cottonwoods crashed onto streets and homes.
Disappearing fish
Then comes the terrifying story of forests, fish and the world's new megafires.

Years ago a brilliant Japanese marine chemist Katsuhiko Matsunaga decided to see if there was any scientific truth behind an old Japanese adage: "If you want to catch a fish, plant a tree."

Matsunaga discovered a fascinating chemical tale behind the ancestral lore, says Beresford-Kroeger.

Decomposing leaves are full of fulvic acid, just one of many humic acids that enrich the soil. The compound is capable of binding with iron in the soil, explains the botanist.

"The earth is rich in iron, but the oceans are poor," she adds.

Decomposing leaves in forested watersheds help to flush iron into the ocean, where it acts as a catalyst for the building of phytoplankton.

Without a supply of oxygenated iron, phytoplankton can't perform photosynthesis and make the rich food that all marine life depends on.

Great wildfires and logging reduce the leaf litter and therefore the amount of iron that flushes into the ocean, which, in turn, reduces the plankton.

With no food the fish disappear.

"That's what the great fires are doing. The fisherman can't expect to catch more fish. It is a terrifying story."

In northern Japan the felling of great deciduous forests in the past have resulted in precipitous declines in fish and oyster populations.

"When forests disappear, the sea dies," Matsunaga wrote.

Science is providing more evidence about the primal importance of forests for all of life on the planet, says Beresford-Kroger.

The good news, she adds, is that more and more young people want governments to address the issues of climate change and overconsumption.

They also want to see damaged forests restored to their original biodiversity, and native and ancient forests better protected from industrial intrusions.

"But we need leadership and people with brains."

She also proposes "SWAT teams" of trained firefighters to engage wildfires that threaten critical watersheds and fisheries.

"We need it and we need it now."

Beresford-Kroger worries that the new plague of hotter and larger wildfires will not only reduce oxygen in the atmosphere, but also release millions of tons of carbon dioxide, the driver of climate disruption.

"At some point the release of CO2 from wildfires is going to start a chemical chain reaction triggering a release of greenhouse gases from the northern benthic areas. This is something we do not understand."

She pauses for a moment.

"Our children deserve a future, and that's my basic thinking. "

The smoke from global forests, she adds, is sending a profound message, but the destruction is not yet a destiny.

"We don't know the future of the forest. It is an extra skin on the planet that harvests the sun's rays."

Diana Beresford-Kroeger will deliver the ninth Haig Brown Lecture on "The Medicine of Trees" on Nov. 1 at the Tidemark Theatre in Campbell River. There will also be a showing of Call of the Forest about her life's work advocating for the protection of the globe's forests. Tickets are available here.

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Tree Teachings: How Forests and Wildfires Are Critically Linked | The Tyee

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I have called up Diana Beresford-Kroeger, the famed Irish botanist and bestselling author, to ask about the megafires that carpeted much of North America in dense smoke last summer. Announcements, Events & more from Tyee and select partners In British Columbia alone, wildfires released between 150 and 200 megatonnes of carbon dioxide in 2017.

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Plant Intelligence and the Importance of Imagination In Science

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Plant Intelligence and the Importance of Imagination In Science

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Monica Gagliano on her experiments demonstrating plant intelligence

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From ancient myths to modern blockbuster movies, humanity has recounted countless stories in which a seemingly inert vegetal world suddenly comes to life to express itself like a person. What if these stories were more than the fruit of vivid imaginations and were based on an underlying truth? Monica Gagliano, Research Associate Professor in Evolutionary Ecology at the University of Western Australia, has courageously illuminated the revolutionary new field of Plant Bioacoustics. She'll share startling cutting-edge research and show how contemporary science has finally begun lifting the veil of our assumptions by beginning to attune its ears to vegetal "voices." She believes this new paradigm will expand our perspectives to provide us with imaginative new solutions to our current eco-cultural predicaments.

Introduction by Kenny Ausubel, Bioneers CEO & Co-Founder.

This speech was given at the 2018 Bioneers Conference.

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Monica Gagliano - Plant Intelligence and the Importance of Imagination In Science

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From ancient myths to modern blockbuster movies, humanity has recounted countless stories in which a seemingly inert vegetal world suddenly comes to life to express itself like a person. What if these stories were more than the fruit of vivid imaginations and were based on an underlying truth?

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Forests Emerge as a Major Overlooked Climate Factor

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Forests Emerge as a Major Overlooked Climate Factor

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The work of Abigail Swann who's work at the intersection of atmospheric science and ecology is finding that forests can influence rainfall and climate from across a continent.

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When Abigail Swann started her career in the mid-2000s, she was one of just a handful of scientists exploring a potentially radical notion: that the green plants living on Earth's surface could have a major influence on the planet's climate. For decades, most atmospheric scientists had focused their weather and climate models on wind, rain and other physical phenomena.

But with powerful computer models that can simulate how plants move water, carbon dioxide and other chemicals between ground and air, Swann has found that vegetation can control weather patterns across huge distances. The destruction or expansion of forests on one continent might boost rainfall or cause a drought halfway around the world.

Swann is now a professor at the University of Washington, where she runs the Ecoclimate lab. She is in the vanguard of a small but growing group of scientists studying how plants shape Earth's weather and climate. Their results could shake up climate science. "None of the atmospheric scientists are thinking about" how plants could influence rainfall, Swann said, though hints had appeared in the scientific literature for decades. And, she added, "it blows the ecology community's mind ... that the plants over here could actually influence the plants over there."

"Many of us are surprised at what a powerful role plants actually play," said Park Williams, a bioclimatologist at Columbia University. "The influence of Earth's surface on large-scale climate is currently a really booming topic, and Abby Swann is one of the emerging leaders in that field."

The Ignored Influence of Plants

The schism between the atmospheric and life sciences that Swann encountered was a holdover from the late 1800s, when the U.S. government proclaimed that planting crops and trees would turn the arid Great Plains wet. The government had embraced a dubious theory pushed by land speculators and rejected the counsel of one of the nation's top scientists, John Wesley Powell. Spurred on by such optimistic but dubious claims, thousands of would-be farmers headed west, only to find that greening the land did not, in fact, make it rain. Many struggled to scrape a living from the dry ground, and the ill-conceived agricultural experiment eventually contributed to the devastating Dust Bowl.

Scientists reacted strongly. Early meteorologists, hoping to save their young field's credibility, rejected the notion that forests influence weather. "Much of the discussion of it, unfortunately, has not been of a purely scientific character," one wrote in 1888 in Science. Meteorology, and later climate science, became the study of air and water. Plants were relegated to passive participant status.

Atmospheric scientists - and everyone else - could be excused for thinking of a stoically standing tree or a gently undulating wheat field as doing little more than passively accepting sunlight, wind and rain. But plants are actually powerful change agents on the planet's surface. They pump water from the ground through their tissues to the air, and they move carbon in the opposite direction, from air to tissue to ground. All the while, leaves split water, harvest and manipulate solar energy, and stitch together hydrogen, oxygen and carbon to produce sugars and starches - the sources of virtually all food for Earth's life.

The key features of this molecular wizardry are pores, called stomata, in plant leaves. A single leaf can contain more than 1 million of these specialized structures. Stomata are essentially microscopic mouths that simultaneously take in carbon dioxide from the air and let out water. As Swann notes, the gas exchange from each stoma - and indeed from each leaf - is, on its own, tiny. But with billions of stomata acting in concert, a single tree can evaporate hundreds of liters of water per day - enough to fill several bathtubs. The world's major forests, which contain hundreds of billions of trees, can move water on almost inconceivably large scales. Antonio Nobre, a climate scientist at Brazil's National Institute for Space Research, has estimated, for example, that the Amazon rainforest discharges around 20 trillion liters of water per day - roughly 17 percent more than even the mighty Amazon River.

Yet the computer models that scientists rely on to predict the future climate don't even come close to acknowledging the power of plants to move water on that scale, Swann said. "They're tiny, but together they are mighty."

Scientists have known since the late 1970s that the Amazon rainforest - the world's largest, at 5.5 million square kilometers - makes its own storms. More recent research reveals that half or more of the rainfall over continental interiors comes from plants cycling water from soil into the atmosphere, where powerful wind currents can transport it to distant places. Agricultural regions as diverse as the U.S. Midwest, the Nile Valley and India, as well as major cities such as Sao Paulo, get much of their rain from these forest-driven "flying rivers." It's not an exaggeration to say that a large fraction of humanity's diet is owing, at least in part, to forest-driven rainfall.

Such results also imply a profound reversal of what we would usually consider cause and effect. Normally we might assume that "the forests are there because it's wet, rather than that it's wet because there are forests," said Douglas Sheil, an environmental scientist at the Norwegian University of Life Sciences campus outside Oslo. But maybe that's all backward. "Could [wet climates] be caused by the forests?" he asked.

Forests in the Arctic

Swann arrived at the University of California, Berkeley, in 2005 to do her doctoral work with Inez Fung, an atmospheric scientist. In the 1980s, Fung had helped pave the way for climate models that included realistic vegetation and associated carbon dioxide fluxes. (Among her other accomplishments, she was a co-author on the 1988 paper with the NASA scientist James Hansen that helped bring climate change to the public's attention.) The model she worked with was state-of-the-art at the time, but, like its counterparts at other research institutions, it could only represent the biosphere simplistically.

By the mid-2000s, models had improved enough that scientists could more precisely study the role plants might play in the climate system. Fung suggested that Swann try foresting the Arctic in a climate model. Trees are colonizing higher latitudes as the globe warms, so it seemed reasonable to ask what impact they would have on the region's climate. Other researchers had previously looked into the potential effects of an expansion of northern spruce forests; unsurprisingly, they found that the Arctic would likely get warmer because those trees' leaves are dark and would absorb more sunlight than virtually any of the tundra, ice and shrubs they might replace. Swann decided to look into what would happen if the encroaching forests were deciduous trees with lighter colored leaves, such as birch or aspen.

In her model, the Arctic did still warm - by about 1 degree Celsius, which was more than she expected. Swann determined that her simulated forests emitted a lot of water vapor, which, like carbon dioxide, is a greenhouse gas that absorbs infrared radiation from Earth and redirects some of it downward. The vapor then caused ice to melt on land and at sea, exposing darker surfaces that absorbed yet more sunlight and grew even warmer. The new forests had set off a feedback loop, amplifying the impact of climate change. The finding hinted at the power that plants could exert over a region's climate.

In a separate study, Swann turned all vegetated areas of temperate North America, Europe and Asia into forest. Again, this exercise exaggerated something already happening in the real world: Satellite data have shown that these continents are greening as former farmland returns to forest, perhaps aided by enhanced atmospheric carbon dioxide and longer growing seasons.

As in the Arctic study, the new trees absorbed sunlight and warmed, adding energy to the climate system. Atmospheric currents then redistributed this energy around the planet. Droughts descended on the southern Amazon and rain fell in the Sahara. These effects were caused by a repositioning of the Hadley cell - the massive conveyor belt of air that rises from the equator, dumps its rain over the tropics, and descends again as dry air at around 30 degrees north and south latitudes, where most of the world's deserts are. Through the influence of plants alone, the Hadley cell had shifted to the north.

Swann had seemingly uncovered a hidden "teleconnection" - a region holding sway over a far distant one through subtle atmospheric mechanisms. Fung wasn't that surprised: Atmospheric scientists have gotten comfortable with such remote influences. In periodic El Niño events, which have been understood since the 1920s, unusually warm surface water in the eastern Pacific Ocean triggers heavy rain in western South America and Africa and droughts in Southeast Asia and Australia. The novelty in Swann's simulated events was that forests, not oceans, did the influencing.

"To me that was a really interesting perspective," said Gordon Bonan, a geoscientist at the National Center for Atmospheric Research in Boulder, Colorado, who also studies the influence of plants on the atmosphere. "If you do enough of this tree planting, you can actually change circulation patterns."

Distant Effects From Forest Changes

Scenarios such as a green Arctic or a reforested temperate zone are not as far-fetched as they may seem. A recent study in Nature reported that in the last three and a half decades, tree cover has increased by more than 2 million square kilometers in these regions.

Massive tree losses are also part of our modern world. During roughly the same period when temperate and boreal trees gained ground, some 20 percent of the Amazon rainforest was cut down. Since 2010, nearly 130 million trees have died in California alone, mostly because of drought and wildfire.

Much effort has gone into understanding how future climate change will affect forests. Based on severe droughts that occurred in 2005, 2010 and 2015, some scientists believe the Amazon may be nearing a tipping point that would cause much of its rainforest to turn to savanna, with potentially devastating consequences for carbon storage, biodiversity and local climate. A paper from late 2017 provided evidence that future warming would make droughts even more lethal to the forests of the American Southwest. Some scientists predict that many of the Southwest's forests could become savanna or grasslands, and at least one - Nate McDowell at Los Alamos National Laboratory - has been quoted as saying that a large fraction of the region's trees could die.

Yet the question of how changes in forests could alter the global climate has barely been considered. "For decades we've been looking to see: How well can we do in climate modeling without needing to evoke the influences of vegetation?" Williams said. "Vegetation has kind of been left on the back burner."

Swann's and Fung's research suggested that plants need to be brought to the fore. And other researchers have taken note. Earlier this year, two groups of scientists, both of which included Swann, authored studies of how forest-driven water transport will change as carbon dioxide levels rise. Studies of individual leaves have shown that when plants are bathed in carbon dioxide, they don't need to make as many stomata per leaf, and they close the ones they do make more of the time. These changes help forest plants conserve water to survive, but they reduce the water vapor available to fall as rain on the surrounding continent. Moreover, when plants transpire, they cool Earth's surface and warm the air, just as the evaporation of sweat cools your body on a hot day. Leaf-level changes, scaled up across continents, could rob the atmosphere of moisture and warm the planet's surface.

To Michael Pritchard, a climatologist at the University of California, Irvine, Swann's results were "very provocative ... and a big wake-up call," he said. "This effect seemed to be rewriting the maps of the drought severity outlook in the future."

Pritchard said he hadn't previously been aware of the stomatal closure effect. The knowledge inspired him to join a group led by Gabriel Kooperman, a climate scientist then at UC Irvine, investigating the future effects of enhanced carbon dioxide over the three major tropical forest regions - the Amazon, Central Africa and Southeast Asia.

In a study published in Nature Climate Change in April, the researchers found that the closing of stomata would cause half the rainfall changes the regions would see by 2100. Moreover, the Amazon - home to the world's most carbon-rich and biodiverse rainforest - would get hit with the most severe declines.

Swann is now probing the effects of forest changes at different scales. In a 2016 paper, she reported that wiping out forests in western North America made forests in eastern South America grow more vigorously, while reducing growth in Europe.

And in a study published in May, she investigated how U.S. forest die-offs would affect forests elsewhere in the country. In her models, she killed off forests in 13 heavily forested regions that the National Science Foundation has identified as being ecologically distinct. The results were dramatic. When she wiped out trees in the Pacific Southwest, forests in the Midwest and eastern U.S. suffered. In recent years, the Pacific Southwest has, in fact, lost an estimated 100 million trees, mostly to droughts and voracious insects.

The effects of forest die-off can also be positive, however. In Swann's study, removing trees from the mid-Atlantic actually helped forests elsewhere, by making those regions' summers cooler or wetter. Swann emphasizes that this does not mean people should cut down forests, which provide innumerable benefits beyond their influence on other regions, including carbon storage, wildlife habitat and water filtration. But she notes that environmental groups often plant trees as a climate solution without considering whether the trees could harm forests elsewhere - or warm the planet by absorbing solar energy.

Massive government-sponsored tree plantings have taken place in China and the African Sahel, for example. No one knows what effects they have had on the global climate. "What we would like to be able to say is, if you plant this amount of trees, you would see this reduction in planetary warming," Bonan said. "We don't really quite have that answer yet."

For Swann, it was a thrill to see any effect. "The smaller down in scale we go, I thought it would be harder and harder to identify these climate responses and subsequent forest responses," she said. "These smaller forest losses still do have big impacts, and actually the impact doesn't just scale with the tree area that's lost."

The Uncertainties Still Matter

Not everyone is sold on ecoclimate teleconnections. Sheil is skeptical of the results of the Kooperman-led study. He thinks climate models do not represent plant biology and the physics of air movement and rainfall accurately enough to say anything meaningful about the real biological world. He notes, for example, that different climate models given the same input often make different predictions.

Others point out that ecoclimate researchers have relied largely on one model, the Community Earth System Model, or CESM. Typically, climate scientists aren't convinced that a phenomenon is real until they have seen it in the output of numerous models; for instance, the next Intergovernmental Panel on Climate Change report will incorporate results from more than 30 models. It's possible that the CESM may be unusually sensitive to vegetation, Pritchard said.

Swann adds a critique of her own: She and her colleagues haven't always been able to piece together the full chain of physical causation through which forests influence distant regions in her models. In her recent paper on U.S. forests, for example, there were too many disparate mechanisms to investigate one by one, she said. The situation is reminiscent of the hypothetical butterfly flapping its wings in Brazil and setting off a tornado in Texas: Swann and her colleagues can set the butterfly fluttering and see the tornado take shape, but they don't fully understand what happens in between. Elucidating such mechanisms will be a focus of future work.

Addressing these concerns won't happen overnight, however. Most models, unlike the CESM, can only be run at a modeling center by the handful of scientists who created them. Those people are busy running simulations for the next Intergovernmental Panel on Climate Change report, due out in 2022. None of the models being used fully account for plants' influence on climate, Swann said.

The historical view that climate science is mainly about physical phenomena still has influence. For more than a decade, climatologists have seen clouds as the biggest source of uncertainty in models. Clouds cool the planet by reflecting incoming sunlight, but they also warm the planet because they are made of water vapor, a greenhouse gas. Models differ wildly on how much clouds will contribute to cooling and warming in the future, and thus whether a doubling of atmospheric carbon dioxide will be problematic but manageable, or catastrophic.

But how much rain will fall in a given region, and when, and how much it will vary season to season and year to year, will make all the difference in determining which places will remain livable and which places won't. And Swann and Fung's results open up at least the possibility that plants could have as much effect as cloud physics on nailing down the answers to such questions.

Moreover, Fung points out, the problems aren't even independent: Forests produce clouds. Without an accurate picture of forests, cloud models will remain incomplete.

That's why Swann is starting a new project: to try to quantify how much plants contribute to the uncertainty in climate model results. With that number in hand, she may have an even more potent tool for convincing other researchers that ecology and atmospheric science are inseparable.

Another potential project involves looking at forest data for observational evidence of the teleconnections found in modeling studies. Swann admits, however, that she's "a little bit on the more skeptical side" that such signals will emerge amid the many pushes and pulls that forests experience. She and David Breshears, an ecologist at the University of Arizona and one of her co-authors on the U.S. forest paper, are also exploring how future southwestern forest losses will affect the climate of the Midwest, the nation's breadbasket and one of the most productive agricultural areas on Earth.

One thing is clear already: Swann's influence is being felt. In just over a decade, ecoclimate teleconnections have gone from being virtually unknown to appearing as a frequent discussion topic at major scientific meetings such as the Ecological Society of America and the American Geophysical Union. No longer are such ideas dismissed as not being "of a purely scientific character."

The developments in this new research area demonstrate that future climate scientists will need to master two fields that have, for more than a century, been largely separate, Fung said: atmospheric physics and biology.

"There are very few 'multilingual' scientists," Fung said. "When Abby did her thing, it was the coming together of two disciplines." She added, "That's how progress is made."

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Forests Emerge as a Major Overlooked Climate Factor | Quanta Magazine

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When Abigail Swann started her career in the mid-2000s, she was one of just a handful of scientists exploring a potentially radical notion: that the green plants living on Earth's surface could have a major influence on the planet's climate. For decades, most atmospheric scientists had focused their weather and climate models on wind, rain and other physical phenomena.

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The role of forests in global climate patterns

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Every tree in the forest is a fountain, sucking water out of the ground through its roots and releasing water vapor into the atmosphere through pores in its foliage. In their billions, they create giant rivers of water in the air - rivers that form clouds and create rainfall hundreds or even thousands of miles away.

But as we shave the planet of trees, we risk drying up these aerial rivers and the lands that depend on them for rain. A growing body of research suggests that this hitherto neglected impact of deforestation could in many continental interiors dwarf the impacts of global climate change. It could dry up the Nile, hobble the Asian monsoon, and desiccate fields from Argentina to the Midwestern United States.

Until recently, the nuggets of data delivering such warnings were fragmented and often relegated to minor scientific journals. But the growing concerns came to the fore in reports presented at two forest forums held by the United Nations and the Norwegian government in recent weeks.

In Norway, Michael Wolosin of the U.S. think tank Forest Climate Analytics and Nancy Harris of the World Resources Institute published a study that concluded that "tropical forest loss is having a larger impact on the climate than has been commonly understood." They warned that large-scale deforestation in any of the three major tropical forest zones of the world - Africa's Congo basin, southeast Asia, and especially the Amazon - could disrupt the water cycle sufficiently to "pose a substantial risk to agriculture in key breadbaskets halfway round the world in parts of the U.S., India, and China."

The water that a single tree transpires daily has a cooling effect equivalent to two domestic air conditioners for a day.

And in a background paper for the UN event, David Ellison of the Swedish University of Agricultural Sciences in Uppsala, reported on "increasingly sophisticated literature" assessing "the potential impact of forest cover on water availability across the broad expanse of continental, terrestrial surface."

It is well known that carbon dioxide emissions from deforestation add 10 percent or so to global warming by reducing the quantity of CO2 that the world's forests pull from the atmosphere. But the authors of both papers say this understanding about global impacts of deforestation has tended to eclipse findings about other "non-carbon" climatic impacts that may play out intensively at local and regional scales.

The impact of deforestation on rainfall is one of the most important non-carbon effects. But there are others. For instance, healthy forests release a range of volatile organic compounds that "have an overall cooling effect on our climate," mostly by blocking incoming solar energy, says Dominick Spracklen of Leeds University in England. Removing forests eliminates this cooling effect and adds to warming, he and an international team concluded in a study published earlier this year.

Meanwhile, lost forests are usually replaced by agriculture, which produces its own emissions. Add in these impacts and the real contribution of deforestation to global climate warming since 1850 is as much as 40 percent, conclude Wolosin and Harris. At that rate, tropical deforestation could add 1.5 degrees Celsius (2.7°Fahrenheit) to global temperatures by 2100 - even if we shut down fossil fuel emissions tomorrow, calculates Natalie Mahowald of Cornell University.

But there are local effects, too. Forests moderate local climate by keeping their local environments cool. They do this partly by shading the land, but also by releasing moisture from their leaves. This process, called transpiration, requires energy, which is extracted from the surrounding air, thus cooling it. A single tree can transpire hundreds of liters of water in a day. Each hundred liters has a cooling effect equivalent to two domestic air conditioners for a day, calculates Ellison.

Monitoring of rapidly deforesting regions of the tropics has recently shown the effect of losing this arboreal air conditioning. Take the Indonesian island of Sumatra, which has been losing forests to palm oil cultivation faster than almost anywhere else on the planet. A study last year found that since 2000, surface temperatures there have on average increased by 1.05 degrees Celsius (1.8°F), compared with 0.45 degrees in forested parts. Clifton Sabajo at the University of Gottingen, Germany, found temperature differences between forest and clear-cut land of up to 10 degrees Celsius (18°F) in parts of Sumatra.

Meanwhile in the Amazon, Michael Coe of the Woods Hole Research Center recently reported a difference of 3 degrees Celsius (5.4°F) between the cool of the forested Xingu indigenous park and surrounding croplands and pastures.

"The forests cause the rainfall, and if they weren't there the interior of these continental areas would be deserts," says one expert.

But heat is only the start. There is drought, too - not just in and around former forest lands, but far away. And a host of new studies are forcing a reassessment of exactly why it rains where it does.

We are used to thinking of rainfall as the end result of water evaporating from the oceans. In coastal regions that is overwhelmingly the case. But it turns out that the interiors of continents often get most of their precipitation from water that has been rained out and recycled back into the air several times in a precipitation cascade following the winds. The further inland, the more dominant this recycling becomes.

Some of the recycling is straightforward evaporation from lakes, rivers, or wet soil. But much of it is fast-tracked by plants, and especially trees. Tree roots tap moisture from deep in the soil. This circulation system is driven by releases of moisture into the air through their leaves via transpiration.

By one estimate, the planet's land vegetation recycles 48 cubic miles of water each day. A tenth of that is released by the Amazon rainforest alone - rather more than the daily discharge of the Amazon River.

Transpiration is essential to generating new rainfall downwind. And the heart of this process is in the surviving tropical rainforests, where transpiration is most intense.

"Traditionally, people have said areas like the Congo and the Amazon have high rainfall because they are located in parts of the world that experience high precipitation," says Doug Sheil of the Norwegian University of Life Sciences, near Oslo. "But the forests cause the rainfall, and if they weren't there the interior of these continental areas would be deserts."

In a study of tropical areas downwind of deforestation, Spracklen found that "air that has passed over extensive vegetation in the preceding few days produces at least twice as much rain as air that has passed over little vegetation." He predicts that forest loss is set to reduce dry-season rainfall across the Amazon basin by 21 percent by 2050.

Arie Staal of Wageningen University in the Netherlands reported earlier this year that one-third of the rain falling in the Amazon basin comes from moisture generated within the basin, mostly by transpiring trees. The dependence was greatest downwind in the west of the basin, farther from the Atlantic Ocean. With a fifth of the Amazon forests gone, the risks of drought grow for such regions. Coe reported less rainfall and a longer dry season in Rondônia, an Amazon province on Brazil's western border with Bolivia.

The Amazon provides moisture as far as the Midwestern U.S., which gets 50 percent of its rainfall from water evaporating from land.

Daniel Ruiz of Columbia University says rainfall in the Colombian Andes is becoming more seasonal, with reduced humidity and fewer clouds. Some researchers believe the desiccation could stretch south to Argentina and north across the Caribbean to North America. The Amazon is thought to provide moisture as far as the Midwest, which gets 50 percent of its rainfall from water evaporating from the land.

Attributing changes in rainfall to altered land use is difficult. But a growing body of research asserts that the fingerprints of deforestation are increasingly visible. In Borneo, an analysis of nine watersheds found that those with the greatest forest loss have seen a reduction in rainfall of around 15 percent. In India, Supantha Paul of the Indian Institute of Technology in Mumbai found that patterns of declining rainfall during the Indian monsoon matched changing forest cover.

Patrick Keys of the Stockholm Resilience Center in Sweden says the downwind effect of deforestation is not limited to the tropics. "China receives a very large fraction of its rainfall from water that is recycled from evaporation on land," he told Yale Environment 360. It "has very high potential for changes to its precipitation driven by upwind land-use change" as far away as Eastern Europe and the jungles of Southeast Asia.

Awaiting Day Zero: Cape Town faces an uncertain water future. Read more.

This matters for farmers, but also for city dwellers. In a study of 29 megacities around the world, Keys found that 19 relied on evaporation and transpiration from land He singled out as the most vulnerable Karachi in Pakistan and China's Shanghai, Wuhan, and Chongqing. Other cities such as Delhi and Kolkata in India, Istanbul, and Moscow were not far behind.

In the Americas, he warned that the Brazilian megacities of Rio de Janeiro and Sao Paulo and Argentina's Buenos Aires could also be vulnerable because much of their rainfall originates in the Mato Grosso region, where forests and grassland are rapidly being replaced by corn and soy fields. And what of Africa, the region of the world whose people are most dependent on rain-fed agriculture? In Africa, drought can mean death. But Keys estimates that up to 40 percent of sub-Saharan rainfall is created by moisture that has been recycled by vegetation. In the arid Sahel region, the figure may rise to 90 percent, says Louis Verchot of the Center for International Forestry Research (CIFOR).

Recent research has highlighted the threat posed by deforestation to the Nile River, the world's longest river, and the 300 million people who depend on it. Most of the Nile's flow begins in the Ethiopian highlands, a small rain-drenched part of the river's catchment. But recent research suggests that much of the rainfall in the Ethiopian highlands comes courtesy of moisture recycled by the forests of West Africa and, especially, the jungles of the Congo basin in the continent's heart. These rainforests "may provide as much as 30 to 40 percent of the total annual rainfall in the Ethiopian highlands," says Ellison.

Two questions arise. Has deforestation in West Africa been responsible for the reduced Nile flows out of Ethiopia seen in the final quarter of the 20 th century, as suggested by Ellison's colleague, Solomon Gebrehiwot, a researcher at Justus-Liebig University, Giessen in Germany. And could future loss of the Congo jungle empty the river further? Sheil says Gebrehiwot's data suggest a further 25 percent decline in Nile flow is a realistic estimate.

Both Keys and Ellison see an urgent need for climate scientists and diplomats alike to begin addressing these issues, so that pressure points can be identified and policies adopted to protect rainfall in critical places. We have treaties governing river flows in most rivers that cross international borders, they point out. But the rivers of moisture in the atmosphere are rarely measured and never governed.

Carbon Loophole: Why is wood burning counted as green energy? Read more.

Egypt and Ethiopia have spent years working toward an agreement on managing water flows in the Nile. But a deal on sharing the water will be pointless if rains falter in the Ethiopian highlands because of deforestation in the distant Congo basin.

In the current human-dominated era of the Anthropocene, says Keys, "processes such as moisture recycling... can, and ought, to be governed."

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Rivers in the Sky: How Deforestation Is Affecting Global Water Cycles

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A growing body of evidence indicates that the continuing destruction of tropical forests is disrupting the movement of water in the atmosphere, causing major shifts in precipitation that could lead to drought in key agricultural areas in China, India, and the U.S. Midwest.

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Global team of scientists find ecosystem below earth that is twice the size of world’s oceans

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Scientists identify vast underground ecosystem containing billions of micro-organisms

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Global team of scientists find ecosystem below earth that is twice the size of world's oceans