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Esteemed Elder, recently passed. Respected around the world

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Esteemed Elder, recently passed. Respected around the world

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Suggested pauses for discussion: 1:40 (hug and talk with trees and water); 2:36 (never take more than you need); 2:55 (expressions of love); 3:30 (Mother Earth is alive)

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Learning how to care for Mother Earth with Elder Dave Courchene

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Many schools/districts dedicated time to SDGs. How might we explicitly connect this project to those?

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Goal 15: Life on land - The Global Goals

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Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss.

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Brilliant case for humus

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Humus - the essential ingredient: Graeme Sait at TEDxNoosa

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Excellent on Cycles, Symbiosis and all soil species  detailed explanation of why conventional farming is so destructive.  More scientific than most

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Excellent on Cycles, Symbiosis and all soil species  detailed explanation of why conventional farming is so destructive.  More scientific than most

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https://www.youtube.com/watch?v=8ugaL6wsXME

This is more scientific and less entertaining--but the content is itself excellent in descriptive with great diagrams.  I like this for its sophistication that is communicated very well. Probably best for individual projects on microorganisms, fungi

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Civics, activism, fostering change

-how to research current state of policies for soil at state level
--how to research/interview best practices locally
--how to share your research & with whom
--how to protect, not protest--what's the difference in us and what we do?
Best practices learned from other causes that have been used for health or farming issues
--history of non-violence

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https://www.youtube.com/watch?v=heMT2XwFXlU

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Become a Planet Protector: Support Reclaimers!

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Example of reclamation in Navajo Nation. 

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Example of reclamation in Navajo Nation. 

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Good, short podcast
Food as medicine, plants as teachers
Meg, I think you'll really like this.

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There's a great deal to learn from the deep connections between regenerative agriculture and the farming traditions of First Nations people. My guest today is James Skeet, a member of the Navajo Nation and the founder of Spirit Farm in New Mexico, a demonstration farm that draws both Native Americans and others to learn more about issues like composting and regenerative farming techniques.

Interview Summary
How would you say that farming and conservation and preservation are a part of your cultural heritage?
As I look back historically and through our traditional perspectives, who we are as a people, indigenous worldview is something that is very important to the earth and to the relationship to the environment, especially here in the Southwest. The climate, it can be harsh as well as very sustainable. A very delicate process. It's not something that can be done quickly. You have to look at seasons rather than what you're producing.
So, James, as people think about the term regenerative agriculture, one might conclude that it's new on the scene? But you're making the point that it's not new on the scene at all, that there are hundreds of generations of people who have been working on doing just this.
Indigenous people have always had this organic mindset that all things are sacred. Nature is to be respected and copied. Time is not linear but secular. There's always been sort of a bartering regenerative economy there, dealing with our relationship with different tribes. And then, food is considered as medicine. Because the plants were here first, they're our grandfathers and grandmothers. So they're teaching us things about that relationship with the environment. And it goes into some deep religious activities, ceremonies to have that relationship.

It's really biology based. We were looking at minimal disturbance, especially when the Navajos went into a sheep economy, which was after the introduction of Churro sheep from the Spaniards. We had some of the tallest grasses in the so-called New World because they were using herding techniques that went from summer camps to winter camps. That relationship with the sheep and the biology and the soil, the grasses, to maximize productivity in the grasses.
My guess is that many people would look at the landscape where you do your farming and think that it just wouldn't be possible to grow enough food to survive there. How would you respond to that?
I would totally agree with that. The way we've understood farming has been based on annual crops, monocropping, productivity, but indigenous people have looked outside of that box to where hunters and gatherers were a type of farming that was taking place with the relationship with their herding animals, as well picking plants as they go along. And what we're trying to do is really a subtle edge, and that's where the complexity of our religions come from. Delicate relationships with Mother Earth and Father Sky. A lot of these ruins dictate to us, now looking back, their dependency on annual crops, corn, beans, squash, a lot of indigenous people all understood the relationship between plants that were outside of that category, the annual crops. They would focus on what we call weeds today. If you study the nutrient density of those plants, their medicinal nutrient values are very high.

My mom was an herbalist. That understanding of our environment has really been misunderstood or overlooked. I really feel like what would we call food deserts, aren't really food deserts. It's in our minds that we think that it's a desert, but in reality what nature, like I said before, grandfathers and grandmothers, are reaching out today and saying, I can heal you if you reestablish that relationship. And that cosmology is really another way of interpreting the goodness of Mother Nature. The idea of sustainability.
Could you tell us a bit more about Spirit Farm, and what inspired you to do this work? And, how do you do things differently than what conventional farmers might do?
Yeah, it really has to do with epistemology, how we view the world, view nature. Do we look at reductionists rather than systems? My wife and I, we were working for a managed care organization for a number of years. But in the back of our minds we felt like, why are indigenous people getting sicker? Why are they unhealthy? And the more we looked into that, we realized that it was the relationship they had with the kinds of foods. They had plenty of food, but it wasn't the right kind of nutrient dense foods.

So, we had to really look at what can we do instead of complaining about the colonization, how we've been overtaken by the European Western world view, what can we do? We decided to just farm, to get back to nature, step off this corporate machinery, and we had some land there that my folks had that my grandfather in the past had plowed the heck out of it. And now, 50, 60 years later, the soil is so bad. Most of the top soil is blown off. We have invasive species that take up a lot of the water underneath the soil. You couldn't really grow anything.

Right at that time we ran across Elaine Ingham, a soil scientist. And then also up here in Gallup, Ann Malloy. They were the ones that tracked us on the biological amendment, doing the thermal compost, putting organic material back into the soil, that the soil is alive. So when I started doing that study of that relationship with, what I call ch-osh doo yit-inii, the unseen bugs, we started sharing a lot of the information with our elders. I remember one grandmother said, "They finally figured us out." And I was asking her, what do you mean by that? And she said, "They finally figured out what we used to do in our planting and what those dances mean, what the clans mean, what their purpose is, what their relationship was."

We found this whole perspective of re-indigenizing, meaning that there were some things that were local, ideas, knowledge, seeds, information on plants, information on relationships, we just stumbled into a whole new arena. And so what happened to our farm was we just decided to provide for ourselves, see if we can grow things for ourselves. But what we came across was conventional farming had taken root, the use of the tractor, the deep plowing, which further messed up the system. And in looking at the microbial activity, what I realized was we were talking about kinship and relationship.

So what we tried to do was give sacredness to the soil and to the bugs that were in the soil that do the job for regenerative farming. And when we did that, we began to hear things, not just from people, not just from our indigenous worldview, but from other farmers and even the plants themselves were communicating things to us. We coined the term "indigenous regenerative intelligence" as our mission.
What sort of things do you grow on the farm?
We've been able to grow just about everything. We don't have a well here on our farm. Everything is captured. And that's our first principle, is looking at water as sacred.

We've been able to grow, of course the three sisters, corns, beans and squash, and we found as we studied that, that relationship was symbiotic. The corn was the windbreaker. The squash was the cover crop that lowered the temperature, and the beans was the nitrogen fixer to the corn because it took a lot of nitrogen out of the soil. But there's one grandma that still grows corn down from us a couple of miles, but they do a lot of dry farming. So she went and plowed the field and grew the corn. Whereas we heavily mulch and we amended it with compost, and we put a lot of the aeration back into the soil. We did a lot of cover crops so that the roots itself can release exudates that draws the microbes in there.

So I said, you take 10 seeds, I'll take 10 seeds. Put mine in, and she put hers in. And at the end of the season she came by and she said, "How's your corn? Where did you plant it? What did you do?" She was asking me a lot of questions. She said her corn reached up to about three to four feet, and she was standing in front of the corn that I grew and it was eight feet tall. We've been able to grow lots of different kinds of tomatoes. Broccoli did very well. We've got a whole herb bed of perennials that come up. I don't even have to mess with that. Some of the soil is getting to the point where we really don't have to amend it, its deep and lush and it smells really good. We've been able to grow sunn hemp for biomass. We've been able to grow 18 different species of cover crops for our sheep to come in and feed on, and do the disturbance teas, a lot of different types of berries. Saskatoon seems to do very well.

So, in looking at ch'osh doo yit-inii, all the unseen bugs, through the microscope and also looking at indigenous cosmology, because to them that's sort of their microscope, we've been able to grow just about everything and anything.
I love hearing your thoughts on these things and what's so impressive are the personal stories, like with the grandmother and your comparison of the corn planted on her land and yours. And then, just your discussion of how you go about the farming. The practice of the farming is really instructive. But I think what comes through so loud and clear, and you discussing this, is the spiritual meaning of all this, and how everything is there for a reason, and how it can be nurtured and cared for in a way that protects the land and protects the creatures that are in it. These things are messages that just not enough people get to hear. Now, I know you go all over and speak about these things. Are audiences receptive, do you think?
I definitely think that what is happening, just to put it simply, is Mother Nature is mad. The reason why it's mad and angry is because the way we've used science and reductionist thinking, industrial conventional farming mindset. It's based on a currency-based economy. Food as a commodity. The use of synthetic fertilizers rather than the biology base. It's very production heavy. Monocropping, you have to have big tractors. It's a very dense disturbance rather than looking at the minimal disturbance.

So, that's spirituality. If we think about it, that's created the fragmentation. That type of thinking has created the systemic racism, ethnic disturbance in countries where people are fighting over state, nation lines, without really considering tribal people groups. Science disembodies itself from the spirit and the soul. That's what's happening to this country and all around the world, is that the haves and have not, winners take all, is taking place.

There's a mindset that's shifting into more the organic indigenous perspective, and those are people that are being drawn to the idea of Spirit Farm. Having concrete, very practical examples of that relationship with what we grow. The biology, the biome that's in our gut as well as the biology that's in the soil, what we feed our animals, all that is a cycle of the use of compost. It's creating a closed system.

I've done a lot of work internationally and one of the things that we've looked at is transformative adaptation. Indigenous people has adapted to European style of urbanization. But now I think what's happening because of all the climate change and the pandemics, we have to look at a transformative adaptation. Transformative challenges the systems of resilience and sustainability. It looks at incremental steps away from why we've gotten to this place, is that we have a marginal perspective that we're outside of that system.

The reductionist mechanical mindset cannot interpret change unless it looks from outside. And because of these marginal perspectives, feminists, Native Americans, tribal people groups, people of color, have been looking at this dominant systems. That has to change. We have to look at a different model through a different lens. In indigenous people, our philosophy is rooted into a story about a coyote, our relationship with the land and the earth. It's not about just spinning abstract ideas up in the air. As my wonderful professor used to say, Alphonse Ortiz, all we're saying is that at least get the pendulum moving towards this organic indigenous mindset. You have to become attached to the land.
I think you've partly answered the question I'm about to ask, but so are you optimistic? Do you believe that people are listening to these messages more? Are practices beginning to change? Are you hopeful?
A lot of these regenerative farmers are swimming up against the current. The mind has to shift into more a secular pattern rather than a linear pattern to realize that it's about the people. Transformative adaptation is really positive because you're not only adapting to the changes, but you're actually transforming the system. We're going to come out in a whole new world from the things that are happening in the environment, and the system is not going to be the same. And that we will have to be willing to change and it's positive because it gives us challenges.

And to tell you the truth, I'm really sick and tired of trying to sustain stuff that doesn't work. The industrial conventional mindset of farming has really caused some major scars. We plowed up the microbial activity that's under the soil. So yeah, I think it's very positive. We can change, and we've always changed. As indigenous people we've always adapted. There's an area that didn't provide a lot of buffalo, or an area that didn't quite provide a lot of fish, or the climate was changed, we moved on. What's positive is it's rooting people back to the earth. It's rooting people back to these marginal perspectives. People are really struggling and they're looking at regenerative intelligence as the way to move.

I've been telling all my farmers, keep doing what you're doing. Keep growing things. Keep that relationship because that's what's going to help transition you, and you'll be able to adapt these changes.

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James Skeet and Joyce Skeet, in partnership with Covenant Pathways, have been organizing food drives on the Navajo Reservation in New Mexico for several years. Their vision is to reintroduce farming with the Navajo Community by sharing permaculture techniques that use less water while increasing plant production. With the addition of a hoop house, the fresh produce will be available for months outside of the growing season.

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E82: Rediscovering Navajo Indigenous Agricultural Wisdom - World Food Policy Center

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There's a great deal to learn from the deep connections between regenerative agriculture and the farming traditions of First Nations people. My guest today is James Skeet, a member of the Navajo Nation and the founder of Spirit Farm in New Mexico, a demonstration farm that draws both Native Americans and others to learn more about issues like composting and regenerative farming techniques.

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Article that demonstrates how humans can be helpful to soil/environment

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Article that demonstrates how humans can be helpful to soil/environment

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Abstract

Human occupation is usually associated with degraded landscapes but 13,000 years of repeated occupation by British Columbia's coastal First Nations has had the opposite effect, enhancing temperate rainforest productivity. This is particularly the case over the last 6,000 years when intensified intertidal shellfish usage resulted in the accumulation of substantial shell middens. We show that soils at habitation sites are higher in calcium and phosphorous. Both of these are limiting factors in coastal temperate rainforests. Western redcedar ( Thuja plicata) trees growing on the middens were found to be taller, have higher wood calcium, greater radial growth and exhibit less top die-back. Coastal British Columbia is the first known example of long-term intertidal resource use enhancing forest productivity and we expect this pattern to occur at archaeological sites along coastlines globally.

Introduction

Humans are usually associated with degraded landscapes and the 'forest primeval' is thought to be free of human influence. Removal of habitat, depletion of soil nutrients, forest productivity declines and reduction in biodiversity are commonly cited outcomes of modern human land-use patterns1,2. There is growing evidence, however, of long-term land and resource-use practices such as soil terracing3, fertilization4, forest management5,6 and controlled burning7, which provide alternative models to human presence resulting in environmental degradation. Here we show that millennia of resource use by coastal First Nations in British Columbia, Canada, contributes significant marine-derived nutrients and alters site conditions that enhance temperate rainforest productivity. We focus on western redcedar ( Thuja plicata Donn ex D. Don), a species of cultural importance throughout the Pacific Northwest of North America8,9, and a valuable timber tree10.

Coastal First Nations of British Columbia have a long and vibrant history, with oral and archaeological data providing evidence of over 13,000 years of repeated occupation. Long-term records of occupation are found on the Central Coast of British Columbia, as sea level has been relatively static throughout the Holocene11,12. The term 'habitation site' refers to a place where people lived in the past resulting in the accumulation of a physical-material record following years of seasonal or multi-seasonal occupation. Most habitation sites are situated near the shoreline, where people lived in proximity to a diversity of terrestrial (for example, root gardens, managed plant resources and mammals) and especially marine (for example, clams and fish) resources13,14,15. Significantly, these resource-use patterns resulted in the importation of shell from the intertidal zone into the terrestrial environment. Typically, the major constituents of habitation site shell middens are shell, rock, bone, charcoal, plant remains (mainly rootlets), artefacts, archaeological features and organic soil.

Disposal and stockpiling of shell, as well as the cultural use of fire, altered the species composition of the forest and understory in and around habitation sites16,17. The legacy of human use is most visibly preserved in the accumulation of substantial shell middens, which in some cases exceed 5 m in depth18 and cover thousands of square meters of forest area as the shells are placed for terracing and drainage or are simply discarded as refuse. Less visible legacies at shell midden sites are the effects of ancient fires in the form of charcoal from repeatedly buried hearths19 and site-level burning before reoccupation20, which increases nutrient availability21 and shifts competition22. Although these sites continue to have important cultural value, many have not been occupied with the same intensity or regularity for at least the last 150-250 years, especially since smallpox epidemics in the nineteenth century23,24. However, the western redcedars that have subsequently grown on these shell middens have been intensively culturally modified for harvesting wood and bark. The vast majority of the study area has not been commercially logged or developed, helping to preserve shell middens, an abundance of culturally modified trees, and many stone fish traps and clam gardens in adjacent intertidal areas25,26.

The long-term human harvesting and deposition of shellfish and other animal remnants from the marine to near-shore environment represents a significant marine-derived nutrient input and modifier of soil pH. Some marine-derived nutrients associated with these sites, such as nitrogen from salmon carcasses moved inland by predators and scavengers such as bears and wolves, have also been demonstrated to be important to community and ecosystem structure27, although these nutrients are expected to deplete relatively quickly28. However, the slow release of calcium from degrading shells (CaCO ₃) is more persistent29. Calcium deficiencies are common in forested ecosystems and have been proposed as a significant contributor to top die-back in western redcedar30, although see ref. 31, a condition that results in the death of tree crowns and could represent a significant economic loss to forestry. Further, the addition of CaCO ₃ and charcoal from fire increases soil pH, which in turn increases the availability of macronutrients such as phosphorous32. Shell midden, as a bulk sedimentary matrix, changes the physical structure of the soil by improving drainage33 while the deposition of charcoal increases the porosity of highly weathered soils and also increases phosphorous34. Increased soil pH and drainage contribute to enhanced forest productivity.

Using a combination of airborne lidar and field-based ecological methods, we examine how the consequences of long-term site occupation, such as shell middens and fire, influence measures of forest productivity at our study site on the Central Coast ( Fig. 1a,b). Forest productivity, expressed by forest canopy height, forest width, vegetation greenness and forest canopy cover (that is, productive forests extending further inland) and vegetation greenness at habitation sites was compared with forests along the entire coast contained within our study area using lidar extracted in 30 × 50 m cells set in from the coastal forest boundary by 10 m ( Fig. 1c).

The study area ( a) includes northwest Calvert Island and southwest Hecate Island on the Central Coast of British Columbia, Canada. ( b) Map of the study area with all habitation sites (red) and control sites (blue). Fire surveys (orange-filled red circles, n=7) and detailed ecological analyses (white-filled red circles, n=6) were carried out on a subset of habitation sites. ( c) Close-up map of habitation site (red circle) with approximate shell midden delineated by transparent red polygon. The blue circle shows the control site. Cells (50 × 30 m) used for extracting lidar data are shown in yellow. Data for base maps from https://catalogue.data.gov.bc.ca/dataset/nts-bc-coastline-polygons-1-250-000-digital-baseline-mapping-nts used with permission under http://open.canada.ca/en/open-government-licence-Canada.

Results

Forest productivity is highest near and on human habitation sites

To explain and understand differences in forest productivity, we obtained eco-cultural parameters (shell midden depth, prevalence of fire, soil nutrients, wood nutrients and individual tree growth metrics) using a paired design with control sites located along the coast in areas with similar forest composition and high productivity, but lacking in shell middens (that is, these sites are assumed not to be habitation sites and archaeological surveys confirm this).

Measures of forest productivity were highest in close proximity to habitation sites and decreased within ∼200 m from the shell midden boundary. Trees growing on habitation sites were taller than those growing off of habitation sites (Welch's two sample t-test: t=2.61, d.f.=12.27, P=0.022; Fig. 2a) and deeper shell middens exhibited a larger effect ( Fig. 2b). This pattern was also observed in forest width ( t=3.34, d.f.=12.36, P=0.006; Fig. 3) and vegetation greenness ( t=3.12, P=0.009; Fig. 4), and, to a lesser extent, forest canopy cover ( t=1.86, d.f.=12.58, P=0.087; Fig. 5). Only the amount of insolation was better than the distance from the shell midden boundary on habitation sites in explaining patterns of forest height across the coastal forests in our study site (28 and 24%, respectively) ( Table 2). The most important factor explaining patterns of forest width was distance from shell midden boundary on habitation sites (38%) ( Table 2). For vegetation greenness and forest canopy cover, distance from habitation site was similar to slope, aspect and elevation in explaining forest productivity patterns (∼20%) ( Table 2).

( a) Forest canopy height (in metres) by distance from the shell midden boundary (red) or distance from random locations (blue) shown with s.d. (red and blue ribbon) of bootstrapped boosted regression tree models, which are an additive regression model where terms are simple trees that are fitted in a forward, stagewise manner52. Mean canopy height across entire study area is shown by a dashed line (15.70 m). All distances are measured within the 30 m ribbon delineated from lidar data. ( b) Box plot of difference in canopy height by site type and the depth of shell midden (deep (D)=dark green, medium depth (M)=green, shallow (S)=light green) with forest canopy height at habitation sites significantly greater than all non-habitation sites ( P=0.02). Control sites are located along the coast in areas without shell midden where 'All' sites include the entire study area shown in yellow in Fig. 1b. Boxes represent first, second and third quartiles with whiskers extending to the highest and lowest value that is within 1.5 × interquartile range (IQR). Significantly higher values are denoted by '*'.

( a) Forest width (in metres) by distance from the shell midden boundary (red) or distance from random locations (blue) shown with s.d. of bootstrapped boosted regression tree models and mean forest width across entire study area shown by a dashed line (82.67 m). ( b) Box plot of difference in canopy height by site type and size of the depth of shell midden (deep (D)=dark green, medium depth (M)=green, shallow (S)=light green) with forest width at habitation sites being significantly greater than all non-habitation sites ( t=3.341, P=0.006). Control sites are located along the coast in areas without shell midden where 'All' sites include the entire study area shown in yellow in Fig. 1. Boxes represent first, second and third quartiles with whiskers extending to the highest and lowest value that is within 1.5 × IQR. Significantly higher values are denoted by '*'.

( a) Vegetation greenness by distance from the shell midden boundary (red) or distance from random locations (blue) shown with s.d. of bootstrapped boosted regression tree models and mean vegetation greenness across entire study area shown by a dashed line (0.117). ( b) Box plot of difference in vegetation greenness by site type and the depth of shell midden (deep (D)=dark green, medium depth (M)=green, shallow (S)=light green) with vegetation greenness at habitation sites being significantly higher compared with all non-habitation sites ( t=3.117, P=0.009). Control sites are located along the coast in areas without shell midden where 'All' sites include the entire study area shown in yellow in Fig. 1. Boxes represent first, second and third quartiles with whiskers extending to the highest and lowest value that is within 1.5 × IQR. Significantly higher values are denoted by '*'.

( a) Forest canopy cover (in percentage) by distance from the shell midden boundary (red) or distance from random locations (blue) shown with s.d. of bootstrapped boosted regression tree models and mean forest canopy cover across entire study area shown by a dashed line (73.01%). ( b) Box plot of difference in forest canopy cover by site type and the depth of shell midden (deep (D)=dark green, medium depth (M)=green, shallow (S)=light green) with forest canopy cover at habitation sites being moderately higher compared with all non-habitation sites ( t=1.857, P=0.087). Control sites are located along the coast in areas without shell midden where 'All' sites include the entire study area shown in yellow in Fig. 1. Boxes represent first, second and third quartiles with whiskers extending to the highest and lowest value that is within 1.5 × IQR.

Table 1 Description of habitation and control sites.

Table 2 Results from bootstrapped boosted tree regression models for measures of forest productivity.

Nutrient modifications enhance forest productivity

Soil from habitation sites can explain these striking differences in productivity, being significantly higher in calcium (nested analysis of variance: F=12.34, d.f.=1, P=0.001; Fig. 6a), phosphorous ( F=7.01, d.f.=1, P=0.012) and pH ( F=19.55, d.f.=1, P=0.001; Fig. 7a), and lower in potassium ( F=5.03, d.f.=1, P=0.032; Fig. 7b). Nitrogen, sulphur and magnesium levels were similar ( Fig. 7c-f). Western redcedar trees growing on habitation sites had significantly higher wood calcium levels ( F=4.41, d.f.=1, P=0.037; Fig. 6b), greater radial growth ( F=23.61, d.f.=1, P<0.001; Fig. 6c) and experienced less top die-back ( χ ²-test=14.19, d.f.=1, P<0.001; Fig. 6d). Lastly, above-ground evidence of fire was exclusively associated with habitation sites ( Table 2) and this may also have contributed to forest productivity.

Levels of calcium in ( a) soil and ( b) western redcedar (T. plicata) wood, and with forest productivity metrics of ( c) radial growth and ( d) the proportion of western redcedar trees exhibiting top die-back (image showing redcedar with (i) and without (ii) top die-back). Red circles correspond to habitation sites with shell middens ( n=6; see Table 1 for details). Blue circles correspond to control sites that were selected based on similar composition (dominance of western redcedar), high productivity and lacking a shell midden (hence was considered not to be a habitation site). Coloured circles are mean values and error bars represent standard error. Image credit: A. Trant.

Habitation sites had ( a) significantly more basic soils (higher pH) ( F=19.55, df=1, P<0.001), ( b) significantly higher potassium (K) in control sites ( F=5.03, df=1, P=0.032) and ( c) significantly higher phosphorous (P) in habitation sites ( F=7.01, df=1, P=0.012). There were no significant differences for ( d) sulphur (S) ( F=1.74, df=1, P=0.196), ( e) nitrogen (N) ( F=1.56, df=1, P=0.218) and ( f) magnesium (Mg) ( F=0.63, P=0.432). Coloured circles are mean values and error bars represent s.e. Significantly higher values are denoted by '*'.

Discussion

Although pre-occupation site productivity is unknown, multiple lines of evidence demonstrate that productivity is enhanced at habitation sites, independent from any site selection effect that may exist.

First, from an ecological and archaeological perspective, the dominant tree species, western redcedar, did not appear in this region until at least 7,000-8,000 Cal BP35,36, with modern vegetation arising 4,000-2,000 Cal BP37, millennia after many of these sites were originally occupied ( Table 1). Second, shell middens and historic fire dramatically change local site topography, nutrient dynamics, soil pH and site drainage. We are therefore confident that current measures of forest productivity are enhanced by these sites being occupied, regardless of site conditions before occupation.

Local patterns in forest productivity in these coastal regions have previously been shown to be primarily driven by insolation (aspect), water retention of soils and nutrient availability38. Our data demonstrate similar effects of these factors, but also reveal that distance from habitation sites is routinely ranked as one of the most important predictors of forest productivity ( Table 2). Thus, shell midden habitation sites and the occurrence of historic fires transform the local site conditions through increased soil pH and macronutrient inputs39,40, better site drainage and more level ground, thus offering a mechanism by which forest productivity is enhanced in an otherwise nutrient-limited ecosystem. Shell middens have been shown to alter soil chemistry resulting in greater vegetation cover and higher species richness29 with qualitative reports of vegetation growing on shell middens being botanically different41, and greener and denser42. However, this is the first known documentation of changes to forest productivity resulting from long-term intertidal resource use patterns. Wider forests around habitation sites may be related to the nutrient and drainage benefits from shell middens. In addition, the cultural use of fire at habitation sites probably extended beyond the boundaries of the shell midden either intentionally or accidentally. Less pronounced effects of habitation sites on forest canopy cover might be influenced more by canopy competition for light than nutrients and site drainage.

We reveal a strong association between habitation sites and low-severity fire. The cool climate, high levels of annual precipitation (>4,000 mm) and low probability of summer lightning on Canada's west coast render lightning-caused fires unlikely43. Historically, low-severity fires may have been an important contributor to increased forest productivity in our study area and may also be associated with active management practices such as land clearing, timber harvesting and promoting culturally important species such as berry-producing shrubs44,45.

Ecosystems with a history of extensive human use through commercial logging, development or other forms of contemporary resource extraction are often considered degraded and disturbed. Here we offer alternative consequences of extensive and long-term human management in coastal areas. Pockets of enhanced forest productivity are associated with increased phosphorous availability resulting from higher soil pH from the slow leaching of calcium from shell middens along with the nutrient amendments of past fires. Taken together, this leads to higher forest productivity than might otherwise be predicted for coastal soils with high nitrogen and low availability of other important nutrients such as calcium46. With a deep time perspective from 13,000 years of repeated occupation of the study area, it is clear that coastal First Nations people have developed practices that enhanced nutrient-limited ecosystems, making the environment that supported them even more productive. Middens containing large amounts of bivalves and univalves47 are common regionally48 and worldwide49, making the patterns we report generalizable to other coastal landscapes.

Methods

Study site

This research was conducted in the Hakai Lúxvbálís Conservancy on Calvert and Hecate Islands (N 51° 38′-W 128° 05′), located on the outer coast of central British Columbia ( Fig. 1). The study site is situated in the very wet hypermaritime subzone (CWHvh2), a variant of the Coastal Western Hemlock biogeoclimatic classification50. The CWHvh2 receives some of the highest annual rainfall in North America (∼4,000 mm) and is characterized by a moderate year-round climate (average temperature 7 °C).

Forests in the nearshore environment are dominated by western redcedar ( T. plicata Donn ex D. Don) and western hemlock ( Tsuga heterophylla [Raf.] Sarg.), with lesser amounts of yellow-cedar ( Cupressus nootkatensis [D.Don] Farjon and Harder) and Sitka spruce ( Picea sitchensis [Bong.] Carr.). Productive forests growing in moderately drained soils are in contrast to the majority of forests in the study area, which exhibit stunted growth forms as a result of prolonged saturation of soils and acidic conditions associated with high rates of peat accumulation51. Compared with inland areas of the British Columbia coast, Calvert and Hecate Islands and are comprised of homogenous and nutrient-poor quartz granodiorite bedrock geology51.

We selected sites ( n=15) in formerly occupied habitations that vary in usage type, intensity, year of establishment and year since last occupied ( Table 1). All habitation sites in this study contain shell middens (>50 cm depth) and were categorized as shallow=50-99 cm, medium=100-249 cm and deep>250 cm. Field sites were compared with lidar analyses of the entire coastline contained within the study area (see below). For detailed ecological sampling and fire surveys, a subset of habitation sites ( n=6 and n=7, respectively) were compared with control sites that were selected for having high productivity, similar forest structure and site attributes (bedrock and surficial till type and extent, aspect, slope and proximately to shore) but lacked any above or below ground evidence of shell midden ( Fig. 1b) and thus are considered not to be habitation sites.

Archaeology

Shell midden sites were identified using map information from the British Columbia Site Inventory Database where possible. Field-based methods were also used to identify previously unrecorded shell middens. Field crews employed different types of subsurface testing methods to identify the extents of these deposits including the use of augers, probes, cores, shovel tests and excavation units. Charcoal and plant macrofossil samples from these tests were selected for radiocarbon dating and sent to the W.M. Keck Carbon Cycle Accelerator Mass Spectrometry Lab at the University of California, Irvine, for analysis.

Remote sensing data

Discrete return airborne scanning lidar was acquired on 15 August 2012 by Terra Remote Sensing Inc. (Sidney, BC, Canada). Lidar was collected from 1,150 m AGL at 100 kHz with a maximum scan angle of 26°. The resulting point data have an average point density of 2 points per m ² with an average vertical accuracy of 15 cm. A digital terrain surface was generated from classified ground returns using triangular irregular network interpolation and rasterized at a spatial resolution of 1.0 m. The terrain model was used to derive elevation, slope, aspect and upstream area layers, as well as to normalize non-ground lidar returns to height above ground surface. Vegetation greenness as expressed in the Normalized Difference Vegetation Index was calculated from SPOT6 images acquired on 10 August 2014 and corrected to surface reflectance.

Boosted regression tree modelling

To evaluate the effect of proximity to habitation sites on vegetation structure compared with other landscape factors we fit a Boosted Regression Tree model for four metrics of forest productivity acquired through remote sensing: forest canopy height, forest width, vegetation greenness, represented by Normalized Difference Vegetation Index, and forest canopy cover. Boosted Regression Tree modelling is flexible, as it accepts both continuous and classified variables and also allows for nonlinear relations52. In addition to the terrain covariates, we also included surface material and coastal morphology and exposure from the British Columbia shorezone map53. The study area has a strong gradient of forest structure perpendicular to the shoreline with productive forests on the coastline and mostly marginally productive vegetation and bog areas inland. To account for this gradient and coastal edge effects, we extracted all vegetation data and the covariates from cells that extended 30 m inland and ran 50 m along the shoreline. These cells were set in 10 m from the coastal forest boundary given that vegetation structure is highly variable due to exposure and edge effects. All model data were averaged to 50 m wide sections of this coastal buffer on the study area ( n=600). Models were built using Boosted Regression Trees from the 'gbm' package in R statistical software54, following the methods described in Friedman55,56. We determined optimal fitting parameters in an initial exploration using tenfold cross-validation at a tree complexity of 4, minimum number of samples per node at 5 and a learning rate of 0.01. The number of trees was optimized for each individual model and was between 700 and 1,400. The only model settings and covariates that varied were distance to habitation and control sites, and we focus on the effect of these parameters. Model performance is indicated by the per cent deviance explained and we consider the effect of individual covariates as their relative influence (as per cent of total deviance explained). Models were bootstrapped (100 runs using 80% of data per run) to generate the s.d. that appears on mean values by distance from habitation site and random location. Differences in forest canopy height, forest width, forest canopy cover and vegetation greenness between habitation sites and non-habitation sites were assessed using a Welch's two-sample t-test.

Fire surveys

We ran belt transects to examine the presence of fire in forests surrounding habitation and control sites ( n=7). The location of transects was randomly assigned proportional to the size of the nearshore site area and transects 6 m wide and 30 m long ( n=3) were completed perpendicular to the shoreline at each site. Trees with a diameter at breast height >15 cm diameter were sampled and tree height, health (top die-back, rot) and decay class were recorded. We also recorded the presence of culturally modified trees, char and fire scars.

Nutrients and tree radial growth

At each habitation and control site ( n=6), we sampled 9-14 western redcedar trees and using a 5.15 mm increment borer, extracted 2 cores at breast height (1.4 m) for determining radial growth and wood nutrient analyses. For each tree, we recorded physical attributes of diameter at breast height, height and health (for example, top die-back). Increment samples for radial growth analyses were air-dried, mounted and sanded to a high polish. All western redcedar samples were measured and counted using a Velmex sliding stage micrometre (precision 0.001 mm). For wood nutrient analyses, increment samples were cut into decadal units using a scalpel under a dissection scope and stored in paper coin envelopes. Three samples from each tree were analysed for macro and micronutrients for the period 1905-1914, 1955-1964 and 2005-2014, representing evenly spaced decadal sections across the longest shared record.

At all habitation and control sites, we collected soil samples using an AMS soil auger with a diameter of 5.7 cm. Soil samples were taken at 30 cm below litter layer where we were assumed to be in the active rooting layer and when shell middens were present, samples were taken from soils developed on top of shell middens. Large roots and plant material were removed from the samples. Samples were stored in plastic bags and refrigerated until analysed. All soil and wood samples were analysed for nutrient content by the North Road Laboratory facility of the Research, Innovation and Knowledge Management Branch of the British Columbia Ministry of Forest, Lands and Natural Resources.

Differences in nutrients and radial growth were determined using a nested analysis of variance with sites being nested within site type (habitation or control). Differences in top die-back between site type were determined using a χ ²-test to account for binary data. To be consistent between approaches, five trees were excluded from analyses, because they were >40 m from the shoreline and hence were outside of the area included in lidar data.

Data availability

The data that support the findings of this study are available from the corresponding author upon request.

Additional information

How to cite this article: Trant, A. J. et al. Intertidal resource use over millennia enhances forest productivity. Nat. Commun. 7:12491 doi: 10.1038/ncomms12491 (2016).

Acknowledgements

This research was supported by funding to B.M.S from the Hakai Institute, an NSERC Discovery Grant (386594-2010), the Canada Foundation for Innovation Leader's Opportunity Fund (26102), the British Columbia Knowledge Development Fund (804609) and the Ian McTaggart Cowan Professorship at the University of Victoria. We thank E. Peterson, C. Munck, B.C. Parks, J. Bennett, C. Darimont, C. Dawson, J. Fisher, O. Fitzpatrick, K. Fretwell, S. Friesen, B. Hawkins, W. Housty, P. Johnson, K. Jordan, A. MacKinnon, J. Maxwell, W. McInnes, I. McKechnie, M. Oelbermann, F. Rahemtulla, J. Reynolds, N. Shackelford, J. Silberg, D. Smith, J. Stafford, N. Turner, E. Urquhart, J. Vickers, E. White and S. Wickham.

Author information

Authors and Affiliations

1. School of Environment, Resources and Sustainability, University of Waterloo, 200 University Avenue West, Waterloo, N2L 3G1, Ontario, Canada

Andrew J. Trant

2. Hakai Institute, Calvert Island, PO Box 309, Heriot Bay, BC V0P 1H0, British Columbia, Canada

Andrew J. Trant, Wiebe Nijland, Kira M. Hoffman, Darcy L. Mathews, Duncan McLaren, Trisalyn A. Nelson & Brian M. Starzomski

3. School of Environmental Studies, University of Victoria, PO Box 1700 STN CSC, Victoria, V8W 2Y2, British Columbia, Canada

Andrew J. Trant, Wiebe Nijland, Kira M. Hoffman, Darcy L. Mathews & Brian M. Starzomski

4. Department of Geography, University of Victoria, PO Box 1700 STN CSC, Victoria, V8W 2Y2, British Columbia, Canada

Wiebe Nijland

5. Department of Anthropology, University of Victoria, PO Box 1700 STN CSC, Victoria, V8W 2Y2, British Columbia, Canada

Duncan McLaren

6. School of Geographical Sciences and Urban Planning, Arizona State University, PO Box 875302, Tempe, 85287-5302, Arizona, USA

Trisalyn A. Nelson

Contributions

A.J.T. and B.M.S. originally conceived the study, with W.N. and K.M.H. adding additional methods. A.J.T., K.M.H., B.M.S., D.M. and D.L.M. conducted the fieldwork. A.J.T. and W.N. performed the data analysis aided by B.M.S., K.M.H. and T.A.N. A.J.T., B.M.S., K.M.H. and W.N. drafted the manuscript. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Andrew J. Trant.

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The authors declare no competing financial interests.

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Trant, A., Nijland, W., Hoffman, K. et al. Intertidal resource use over millennia enhances forest productivity. Nat Commun 7, 12491 (2016). https://doi.org/10.1038/ncomms12491
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Intertidal resource use over millennia enhances forest productivity - Nature Communications

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Human occupation is usually associated with degraded landscapes but 13,000 years of repeated occupation by British Columbia's coastal First Nations has had the opposite effect, enhancing temperate rainforest productivity. This is particularly the case over the last 6,000 years when intensified intertidal shellfish usage resulted in the accumulation of substantial shell middens.

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Land degradation affects people and ecosystems throughout the planet and is both affected by climate change and contributes to it. In this report, land degradation is defined as a negative trend in land condition, caused by direct or indirect human-induced processes including anthropogenic climate change, expressed as long-term reduction or loss of at least one of the following: biological productivity, ecological integrity, or value to humans. Forest degradation is land degradation that occurs in forest land. Deforestation is the conversion of forest to non-forest land and can result in land degradation. {4.1.3}
Land degradation adversely affects people's livelihoods (very high confidence) and occurs over a quarter of the Earth's ice-free land area (medium confidence). The majority of the 1.3 to 3.2 billion affected people (low confidence) are living in poverty in developing countries (medium confidence).
Land-use changes and unsustainable land management are direct human causes of land degradation ( very high confidence), with agriculture being a dominant sector driving degradation ( very high confidence). Soil loss from conventionally tilled land exceeds the rate of soil formation by >2 orders of magnitude ( medium confidence). Land degradation affects humans in multiple ways, interacting with social, political, cultural and economic aspects, including markets, technology, inequality and demographic change ( very high confidence). Land degradation impacts extend beyond the land surface itself, affecting marine and freshwater systems, as well as people and ecosystems far away from the local sites of degradation ( very high confidence). {4.1.6, 4.2.1, 4.2.3, 4.3, 4.6.1, 4.7, Table 4.1}

Climate change exacerbates the rate and magnitude of several ongoing land degradation processes and introduces new degradation patterns (high confidence). Human-induced global warming has already caused observed changes in two drivers of land degradation: increased frequency, intensity and/or amount of heavy precipitation ( medium confidence); and increased heat stress ( high confidence). In some areas sea level rise has exacerbated coastal erosion ( medium confidence). Global warming beyond present day will further exacerbate ongoing land degradation processes through increasing floods ( medium confidence), drought frequency and severity ( medium confidence), intensified cyclones ( medium confidence), and sea level rise ( very high confidence), with outcomes being modulated by land management ( very high confidence). Permafrost thawing due to warming ( high confidence), and coastal erosion due to sea level rise and impacts of changing storm paths ( low confidence), are examples of land degradation affecting places where it has not typically been a problem. Erosion of coastal areas because of sea level rise will increase worldwide ( high confidence). In cyclone prone areas, the combination of sea level rise and more intense cyclones will cause land degradation with serious consequences for people and livelihoods ( very high confidence). {4.2.1, 4.2.2, 4.2.3, 4.4.1, 4.4.2, 4.9.6, Table 4.1}
Land degradation and climate change, both individually and in combination, have profound implications for natural resource-based livelihood systems and societal groups (high confidence)

The number of people whose livelihood depends on degraded lands has been estimated to be about 1.5 billion worldwide ( very low confidence). People in degraded areas who directly depend on natural resources for subsistence, food security and income, including women and youth with limited adaptation options, are especially vulnerable to land degradation and climate change ( high confidence). Land degradation reduces land productivity and increases the workload of managing the land, affecting women disproportionally in some regions. Land degradation and climate change act as threat multipliers for already precarious livelihoods ( very high confidence), leaving them highly sensitive to extreme climatic events, with consequences such as poverty and food insecurity ( high confidence) and, in some cases, migration, conflict and loss of cultural heritage ( low confidence). Changes in vegetation cover and distribution due to climate change increase the risk of land degradation in some areas ( medium confidence). Climate change will have detrimental effects on livelihoods, habitats and infrastructure through increased rates of land degradation ( high confidence) and from new degradation patterns ( low evidence, high agreement). {4.1.6, 4.2.1, 4.7}

Land degradation is a driver of climate change through emission of greenhouse gases (GHGs) and reduced rates of carbon uptake (very high confidence). Since 1990, globally the forest area has decreased by 3% ( low confidence) with net decreases in the tropics and net increases outside the tropics ( high confidence). Lower carbon density in re-growing forests, compared to carbon stocks before deforestation, results in net emissions from land-use change ( very high confidence). Forest management that reduces carbon stocks of forest land also leads to emissions, but global estimates of these emissions are uncertain. Cropland soils have lost 20-60% of their organic carbon content prior to cultivation, and soils under conventional agriculture continue to be a source of GHGs ( medium confidence). Of the land degradation processes, deforestation, increasing wildfires, degradation of peat soils, and permafrost thawing contribute most to climate change through the release of GHGs and the reduction in land carbon sinks following deforestation ( high confidence). Agricultural practices also emit non-CO ₂ GHGs from soils and these emissions are exacerbated by climate change ( medium confidence). Conversion of primary to managed forests, illegal logging and unsustainable forest management result in GHG emissions ( very high confidence) and can have additional physical effects on the regional climate including those arising from albedo shifts ( medium confidence). These interactions call for more integrative climate impact assessments. {4.2.2, 4.3, 4.5.4, 4.6}

Large-scale implementation of dedicated biomass production for bioenergy increases competition for land with potentially serious consequences for food security and land degradation (high confidence). Increasing the extent and intensity of biomass production, for example, through fertiliser additions, irrigation or monoculture energy plantations, can result in local land degradation. Poorly implemented intensification of land management contributes to land degradation (e.g., salinisation from irrigation) and disrupted livelihoods ( high confidence). In areas where afforestation and reforestation occur on previously degraded lands, opportunities exist to restore and rehabilitate lands with potentially significant co-benefits ( high confidence) that depend on whether restoration involves natural or plantation forests. The total area of degraded lands has been estimated at 10-60 Mkm ² ( very low confidence). The extent of degraded and marginal lands suitable for dedicated biomass production is highly uncertain and cannot be established without due consideration of current land use and land tenure. Increasing the area of dedicated energy crops can lead to land degradation elsewhere through indirect land-use change ( medium confidence). Impacts of energy crops can be reduced through strategic integration with agricultural and forestry systems ( high confidence) but the total quantity of biomass that can be produced through synergistic production systems is unknown. {4.1.6, 4.4.2, 4.5, 4.7.1, 4.8.1, 4.8.3, 4.8.4, 4.9.3}

Reducing unsustainable use of traditional biomass reduces land degradation and emissions of CO 2 while providing social and economic co-benefits (very high confidence). Traditional biomass in the form of fuelwood, charcoal and agricultural residues remains a primary source of energy for more than one-third of the global population, leading to unsustainable use of biomass resources and forest degradation and contributing around 2% of global GHG emissions ( low confidence). Enhanced forest protection, improved forest and agricultural management, fuel-switching and adoption of efficient cooking and heating appliances can promote more sustainable biomass use and reduce land degradation, with co-benefits of reduced GHG emissions, improved human health, and reduced workload especially for women and youth ( very high confidence). {4.1.6, 4.5.4}

Land degradation can be avoided, reduced or reversed by implementing sustainable land management, restoration and rehabilitation practices that simultaneously provide many co-benefits, including adaptation to and mitigation of climate change (high confidence). Sustainable land management involves a comprehensive array of technologies and enabling conditions, which have proven to address land degradation at multiple landscape scales, from local farms ( very high confidence) to entire watersheds ( medium confidence). Sustainable forest management can prevent deforestation, maintain and enhance carbon sinks and can contribute towards GHG emissions-reduction goals. Sustainable forest management generates socio-economic benefits, and provides fibre, timber and biomass to meet society's growing needs. While sustainable forest management sustains high carbon sinks, the conversion from primary forests to sustainably managed forests can result in carbon emission during the transition and loss of biodiversity ( high confidence). Conversely, in areas of degraded forests, sustainable forest management can increase carbon stocks and biodiversity ( medium confidence). Carbon storage in long-lived wood products and reductions of emissions from use of wood products to substitute for emissions-intensive materials also contribute to mitigation objectives. {4.8, 4.9, Table 4.2}

Lack of action to address land degradation will increase emissions and reduce carbon sinks and is inconsistent with the emissions reductions required to limit global warming to 1.5°C or 2°C. (high confidence). Better management of soils can offset 5-20% of current global anthropogenic GHG emissions ( medium confidence). Measures to avoid, reduce and reverse land degradation are available but economic, political, institutional, legal and socio-cultural barriers, including lack of access to resources and knowledge, restrict their uptake ( very high confidence). Proven measures that facilitate implementation of practices that avoid, reduce, or reverse land degradation include tenure reform, tax incentives, payments for ecosystem services, participatory integrated land-use planning, farmer networks and rural advisory services. Delayed action increases the costs of addressing land degradation, and can lead to irreversible biophysical and human outcomes ( high confidence). Early actions can generate both site-specific and immediate benefits to communities affected by land degradation, and contribute to long-term global benefits through climate change mitigation ( high confidence). {4.1.5, 4.1.6, 4.7.1, 4.8, Table 4.2}

Even with adequate implementation of measures to avoid, reduce and reverse land degradation, there will be residual degradation in some situations (high confidence). Limits to adaptation are dynamic, site specific and determined through the interaction of biophysical changes with social and institutional conditions. Exceeding the limits of adaptation will trigger escalating losses or result in undesirable changes, such as forced migration, conflicts, or poverty. Examples of potential limits to adaptation due to climate-change-induced land degradation are coastal erosion (where land disappears, collapsing infrastructure and livelihoods due to thawing of permafrost), and extreme forms of soil erosion. {4.7, 4.8.5, 4.8.6, 4.9.6, 4.9.7, 4.9.8}

Land degradation is a serious and widespread problem, yet key uncertainties remain concerning its extent, severity, and linkages to climate change (very high confidence). Despite the difficulties of objectively measuring the extent and severity of land degradation, given its complex and value-based characteristics, land degradation represents - along with climate change - one of the biggest and most urgent challenges for humanity ( very high confidence). The current global extent, severity and rates of land degradation are not well quantified. There is no single method by which land degradation can be measured objectively and consistently over large areas because it is such a complex and value-laden concept ( very high confidence). However, many existing scientific and locally-based approaches, including the use of indigenous and local knowledge, can assess different aspects of land degradation or provide proxies. Remote sensing, corroborated by other data, can generate geographically explicit and globally consistent data that can be used as proxies over relevant time scales (several decades). Few studies have specifically addressed the impacts of proposed land-based negative emission technologies on land degradation. Much research has tried to understand how livelihoods and ecosystems are affected by a particular stressor - for example, drought, heat stress, or waterlogging. Important knowledge gaps remain in understanding how plants, habitats and ecosystems are affected by the cumulative and interacting impacts of several stressors, including potential new stressors resulting from large-scale implementation of negative emission technologies. {4.10}

This chapter examines the scientific understanding of how climate change impacts land degradation, and vice versa, with a focus on non-drylands. Land degradation of drylands is covered in Chapter 3. After providing definitions and the context (Section 4.1) we proceed with a theoretical explanation of the different processes of land degradation and how they are related to climate and to climate change, where possible (Section 4.2). Two sections are devoted to a systematic assessment of the scientific literature on status and trend of land degradation (Section 4.3) and projections of land degradation (Section 4.4). Then follows a section where we assess the impacts of climate change mitigation options, bioenergy and land-based technologies for carbon dioxide removal (CDR), on land degradation (Section 4.5). The ways in which land degradation can impact on climate and climate change are assessed in Section 4.6. The impacts of climate-related land degradation on human and natural systems are assessed in Section 4.7. The remainder of the chapter assesses land degradation mitigation options based on the concept of sustainable land management: avoid, reduce and reverse land degradation (Section 4.8), followed by a presentation of eight illustrative case studies of land degradation and remedies (Section 4.9). The chapter ends with a discussion of the most critical knowledge gaps and areas for further research (Section 4.10).

Sustainable land management (SLM) is defined as 'the stewardship and use of land resources, including soils, water, animals and plants, to meet changing human needs, while simultaneously ensuring the long-term productive potential of these resources and the maintenance of their environmental functions' - adapted from World Overview of Conservation Approaches and Technologies (WOCAT n.d.). Achieving the objective of ensuring that productive potential is maintained in the long term will require implementation of adaptive management and 'triple loop learning', that seeks to monitor outcomes, learn from experience and emerging new knowledge, modifying management accordingly (Rist et al. 201354).

Sustainable Forest Management (SFM) is defined as 'the stewardship and use of forests and forest lands in a way, and at a rate, that maintains their biodiversity, productivity, regeneration capacity, vitality and their potential to fulfill, now and in the future, relevant ecological, economic and social functions, at local, national, and global levels, and that does not cause damage to other ecosystems' (Forest Europe 199355; Mackey et al. 201556). This SFM definition was developed by the Ministerial Conference on the Protection of Forests in Europe and has since been adopted by the Food and Agriculture Organization. Forest management that fails to meet these sustainability criteria can contribute to land degradation.

Land degradation can be reversed through restoration and rehabilitation. These terms are defined in the Glossary, along with other terms that are used but not explicitly defined in this section of

the report. While the definitions of SLM and SFM are very similar and could be merged, both are included to maintain the subtle differences in the existing definitions. SFM can be considered a subset of SLM - that is, SLM applied to forest land.

Climate change impacts interact with land management to determine sustainable or degraded outcome (Figure 4.1). Climate change can exacerbate many degradation processes (Table 4.1) and introduce novel ones (e.g., permafrost thawing or biome shifts). To avoid, reduce or reverse degradation, land management activities can be selected to mitigate the impact of, and adapt to, climate change. In some cases, climate change impacts may result in increased productivity and carbon stocks, at least in the short term. For example, longer growing seasons due to climate warming can lead to higher forest productivity (Henttonen et al. 201757; Kauppi et al. 201458; Dragoni et al. 201159), but warming alone may not increase productivity where other factors such a water supply are limiting (Hember et al. 201760).

The types and intensity of human land-use and climate change impacts on lands affect their carbon stocks and their ability to operate as carbon sinks. In managed agricultural lands, degradation can result in reductions of soil organic carbon stocks, which also adversely affects land productivity and carbon sinks (Figure 4.1).

The transition from natural to managed forest landscapes usually results in an initial reduction of landscape-level carbon stocks. The magnitude of this reduction is a function of the differential in frequency of stand-replacing natural disturbances (e.g., wildfires) and harvest disturbances, as well as the age-dependence of these disturbances (Harmon et al. 199061; Kurz et al. 199862; Trofymow et al. 200863).

SFM applied at the landscape scale to existing unmanaged forests can first reduce average forest carbon stocks and subsequently increase the rate at which CO ₂ is removed from the atmosphere, because net ecosystem production of forest stands is highest in intermediate stand ages (Kurz et al. 201364; Volkova et al. 201865; Tang et al. 201466). The net impact on the atmosphere depends on the magnitude of the reduction in carbon stocks, the fate of the harvested biomass (i.e. use in short - or long-lived products and for bioenergy, and therefore displacement of emissions associated with GHG-intensive building materials and fossil fuels), and the rate of regrowth. Thus, the impacts of SFM on one indicator (e.g., past reduction in carbon stocks in the forested landscape) can be negative, while those on another indicator (e.g., current forest productivity and rate of CO ₂ removal from the atmosphere, avoided fossil fuel emissions) can be positive. Sustainably managed forest landscapes can have a lower biomass carbon density than unmanaged forest, but the younger forests can have a higher growth rate, and therefore contribute stronger carbon sinks than older forests (Trofymow et al. 200867; Volkova et al. 201868; Poorter et al. 201669).

Selective logging and thinning can maintain and enhance forest productivity and achieve co-benefits when conducted with due care for the residual stand and at intensity and frequency that does not exceed the rate of regrowth (Romero and Putz 201870). In contrast, unsustainable logging practices can lead to stand-level degradation. For example, degradation occurs when selective logging (high-grading) removes valuable large-diameter trees, leaving behind damaged, diseased, non-commercial or otherwise less productive trees, reducing carbon stocks and also adversely affecting subsequent forest recovery (Belair and Ducey 201871; Nyland 199272).

Land degradation results from a complex chain of causes making the clear distinction between direct and indirect drivers difficult. In the context of climate change, an additional complex aspect is brought by the reciprocal effects that both processes have on each other (i.e. climate change influencing land degradation and vice versa). In this chapter, we use the terms 'processes' and 'drivers' with the following meanings:

Processes of land degradation are those direct mechanisms by which land is degraded and are similar to the notion of 'direct drivers' in the Millennium Ecosystem Assessment framework (Millennium Ecosystem Assessment, 2005135). A comprehensive list of land degradation processes is presented in Table 4.1.

Drivers of land degradation are those indirect conditions which may drive processes of land degradation and are similar to the notion of 'indirect drivers' in the Millennium Ecosystem Assessment framework. Examples of indirect drivers of land degradation are changes in land tenure or cash crop prices, which can trigger land-use or management shifts that affect land degradation.

An exact demarcation between processes and drivers is not possible. Drought and fires are described as drivers of land degradation in the next section but they can also be a process: for example, if repeated fires deplete seed sources, they can affect regeneration and succession of forest ecosystems. The responses to land degradation follow the logic of the LDN concept: avoiding, reducing and reversing land degradation (Orr et al. 2017136; Cowie et al. 2018137).

In research on land degradation, climate and climate variability are often intrinsic factors. The role of climate change, however, is less articulated. Depending on what conceptual framework is used, climate change is understood either as a process or a driver of land degradation, and sometimes both.

The scientific literature on land degradation often excludes forest degradation, yet here we attempt to assess both issues. Because of the different bodies of scientific literature, we assess land degradation and forest degradation under different sub-headings and, where possible, draw integrated conclusions.

Quantifying degradation in forests has also proven difficult. Remote sensing based inventory methods can measure reductions in canopy cover or carbon stocks more easiliy than reductions in biological productivity, losses of ecological integrity or value to humans. However, the causes of reductions in canopy cover or carbon stocks can be many (Curtis et al. 2018459), including natural disturbances (e.g., fires, insects and other forest pests), direct human activities (e.g., harvest, forest management) and indirect human impacts (such as climate change) and these may not reduce long-term biological productivity. In many boreal, some temperate and other forest types natural disturbances are common, and consequently these disturbance-adapted forest types are comprised of a mosaic of stands of different ages and stages of stand recovery following natural disturbances. In those managed forests where natural disturbances are uncommon or suppressed, harvesting is the primary determinant of forest age-class distributions.

The lack of a consistent definition of forest degradation also affects the ability to establish estimates of the rates or impacts of forest degradation because the drivers of degradation are not clearly defined (Sasaki and Putz 2009465). Moreover, the literature at times confounds estimates of forest degradation and deforestation (i.e., the conversion of forest to non-forest land uses). Deforestation is a change in land use, while forest degradation is not, although severe forest degradation can ultimately lead to deforestation.

The trends of productivity shown by several remote-sensing studies (see previous section) are largely consistent with mapping of forest cover and change using a 34-year time series of coarse resolution satellite data (NOAA AVHRR) (Song et al. 2018468). This study, based on a thematic classification of satellite data, suggests that (i) global tree canopy cover increased by 2.24 million km ² between 1982 and 2016 (corresponding to +7.1%) but with regional differences that contribute a net loss in the tropics and a net gain at higher latitudes, and (ii) the fraction of bare ground decreased by 1.16 million km ² (corresponding to -3.1%), mainly in agricultural regions of Asia (Song et al. 2018469), see Figure 4.5. Other tree or land cover datasets show opposite global net trends (Li et al. 2018b470), but high agreement in terms of net losses in the tropics and large net gains in the temperate and boreal zones (Li et al. 2018b471; Song et al. 2018472; Hansen et al. 2013473). Differences across global estimates are further discussed in Chapter 1 (Section 1.1.2.3) and Chapter 2.

The changes detected from 1982 to 2016 were primarily linked to direct human action, such as land-use changes (about 60% of the observed changes), but also to indirect effects, such as human-induced climate change (about 40% of the observed changes) (Song et al. 2018474), a finding also supported by a more recent study (Chen et al. 2019475). The climate-induced effects were clearly discernible in some regions, such as forest decline in the US Northwest due to increasing pest infestation and increasing fire frequency (Lesk et al. 2017476; Abatzoglou and Williams 2016477; Seidl et al. 2017478), warming-induced

vegetation increase in the Arctic region, general greening in the Sahel probably as a result of increasing rainfall and atmospheric CO ₂, and advancing treelines in mountain regions (Song et al. 2018479). Keenan et al. (2015)480 and Sloan and Sayer (2015)481 studied the 2015 Forest Resources Assessment (FRA) of the Food and Agriculture Organization of the United Nations (FAO) (FAO 2016482) and found that the total forest area from 1990 to 2015 declined by 3%, an estimate that is supported by a global remote-sensing assessment of forest area change that found a 2.8% decline between 1990-2010 (D'Annunzio et al. 2017483; Lindquist and D'Annunzio 2016484). The trend in deforestation is, however, contradicted between these two global assessments, with FAO (2016) suggesting that deforestation is slowing down, while the remote sensing assessments finds it to be accelerating (D'Annunzio et al. 2017485). Recent estimates (Song et al. 2018486) owing to semantic and methodological differences (see Chapter 1, Section 1.1.2.3) suggest that global tree cover has increased over the period 1982-2016, which contradicts the forest area dynamics assessed by FAO (2016)487 and Lindquist and D'Annunzio (2016)488. The loss rate in tropical forest areas from 2010 to 2015 is 55,000 km ² yr⁻¹. According to the FRA, the global natural forest area also declined from 39.61 Mkm ² to 37.21 Mkm ² during the period 1990 to 2015 (Keenan et al. 2015489).

Since 1850, deforestation globally contributed 77% of the emissions from land-use and land-cover change while degradation contributed 10% (with the remainder originating from non-forest land uses) (Houghton and Nassikas 2018490). That study also showed large temporal and regional differences with northern mid-latitude forests currently contributing to carbon sinks due to increasing forest area and forest management. However, the contribution to carbon emissions of degradation as percentage of total forest emissions (degradation and deforestation) are uncertain, with estimates varying from 25% (Pearson et al. 2017491) to nearly 70% of carbon losses (Baccini et al. 2017492). The 25% estimate refers to an analysis of 74 developing countries within tropical and subtropical regions covering 22 million km ² for the period 2005-2010, while the 70% estimate refers to an analysis of the tropics for the period 2003-2014, but, by and large, the scope of these studies is the same. Pearson et al. (2017)493 estimated annual gross emissions of 2.1 GtCO ₂, of which 53% were derived from timber harvest, 30% from woodfuel harvest and 17% from forest fire. Estimating gross emissions only, creates a distorted representation of human impacts on the land sector carbon cycle. While forest harvest for timber and fuelwood and land-use change (deforestation) contribute to gross emissions, to quantify impacts on the atmosphere, it is necessary to estimate net emissions, that is, the balance of gross emissions and gross removals of carbon from the atmosphere through forest regrowth (Chazdon et al. 2016a494; Poorter et al. 2016495; Sanquetta et al. 2018496).

Current efforts to reduce atmospheric CO ₂ concentrations can be supported by reductions in forest-related carbon emissions and increases in sinks, which requires that the net impact of forest management on the atmosphere be evaluated (Griscom et al. 2017497). Forest management and the use of wood products in GHG mitigation strategies result in changes in forest ecosystem carbon stocks, changes in harvested wood product carbon stocks, and potential changes in emissions resulting from the use of wood products and forest biomass that substitute for other emissions-intensive materials such as concrete, steel and fossil fuels (Kurz et al. 2016498; Lemprière et al. 2013499; Nabuurs et al. 2007500). The net impact of these changes on GHG emissions and removals, relative to a scenario without forest mitigation actions, needs to be quantified, (e.g., Werner et al. 2010501; Smyth et al. 2014502; Xu et al. 2018503). Therefore, reductions in forest ecosystem carbon stocks alone are an incomplete estimator of the impacts of forest management on the atmosphere (Nabuurs et al. 2007504; Lemprière et al. 2013505; Kurz et al. 2016506; Chen et al. 2018b507). The impacts of forest management and the carbon storage in long-lived products and landfills vary greatly by region, however, because of the typically much shorter lifespan of wood products produced from tropical regions compared to temperate and boreal regions (Earles et al. 2012508; Lewis et al. 2019509; Iordan et al. 2018510) (Section 4.8.4).

Assessments of forest degradation based on remote sensing of changes in canopy density or land cover, (e.g., Hansen et al. 2013511; Pearson et al. 2017512) quantify changes in above-ground biomass carbon stocks and require additional assumptions or model-based analyses to also quantify the impacts on other ecosystem carbon pools including below-ground biomass, litter, woody debris and soil carbon. Depending on the type of disturbance, changes in above-ground biomass may lead to decreases or increases in other carbon pools, for example, windthrow and insect-induced tree mortality may result in losses in above-ground biomass that are (initially) offset by corresponding increases in dead organic matter carbon pools (Yamanoi et al. 2015513; Kurz et al. 2008514), while deforestation will reduce the total ecosystem carbon pool (Houghton et al. 2012515).

As economies evolve, the patterns of land-use and carbon stock changes associated with human expansion into forested areas often include a period of rapid decline of forest area and carbon stocks, recognition of the need for forest conservation and rehabilitation, and a transition to more sustainable land management that is often associated with increasing carbon stocks, (e.g., Birdsey et al. 2006524). Developed and developing countries around the world are in various stages of forest transition (Kauppi et al. 2018525; Meyfroidt and Lambin 2011526). Thus, opportunities exist for SFM to contribute to atmospheric carbon targets through reduction of deforestation and degradation, forest conservation, forest restoration, intensification of management, and enhancements of carbon stocks in forests and harvested wood products (Griscom et al. 2017527) ( medium evidence, medium agreement).

Land degradation will be affected by climate change in both direct and indirect ways, and land degradation will, to some extent, also feed back into the climate system. The direct impacts are those in which climate and land interact directly in time and space. Examples of direct impacts are when increasing rainfall intensity exacerbates soil erosion, or when prolonged droughts reduce the vegetation cover of the soil, making it more prone to erosion and nutrient depletion. The indirect impacts are those where climate change impacts and land degradation are separated in time and/or space. Examples of such impacts are when declining agricultural productivity due to climate change drives an intensification of agriculture elsewhere, which may cause land degradation. Land degradation, if sufficiently widespread, may also feed back into the climate system by reinforcing ongoing climate change.

Although climate change is exacerbating many land degradation processes ( high to very high confidence), prediction of future land degradation is challenging because land management practices determine, to a very large extent, the state of the land. Scenarios of climate change in combination with land degradation models can provide useful knowledge on what kind and extent of land management will be necessary to avoid, reduce and reverse land degradation.

While Chapter 2 has its focus on land cover changes and their impacts on the climate system, this chapter focuses on the influences of individual land degradation processes on climate (see Table 4.1) which may or may not take place in association with land cover changes. The effects of land degradation on CO ₂ and other GHGs as well as those on surface albedo and other physical controls of the global radiative balance are discussed.

Unravelling the impacts of climate-related land degradation on poverty and livelihoods is highly challenging. This complexity is due to the interplay of multiple social, political, cultural and economic factors, such as markets, technology, inequality, population growth, (Barbier and Hochard 2018841) each of which interact and shape the ways in which social-ecological systems respond (Morton 2007842). We find limited evidence attributing the impacts of climate-related land degradation to poverty and livelihoods, with climate often not distinguished from any other driver of land degradation. Climate is nevertheless frequently noted as a risk multiplier for both land degradation and poverty ( high agreement, robust evidence) and is one of many stressors people live with, respond to and adapt to in their daily lives (Reid and Vogel 2006843). Climate change is considered to exacerbate land degradation and potentially accelerate it due to heat stress, drought, changes to evapotranspiration rates and biodiversity, as well as a result of changes to environmental conditions that allow new pests and diseases to thrive (Reed and Stringer 2016844). In general terms, the climate (and climate change) can increase human and ecological communities' sensitivity to land degradation. Land degradation then leaves livelihoods more sensitive to the impacts of climate change and extreme climatic events ( high agreement, robust evidence). If human and ecological communities exposed to climate change and land degradation are sensitive and cannot adapt, they can be considered vulnerable to it; if they are sensitive and can adapt, they can be considered resilient (Reed and Stringer 2016845). The impacts of land degradation will vary under a changing climate, both spatially and temporally, leading some communities and ecosystems to be more vulnerable or more resilient than others under different scenarios. Even within communities, groups such as women and youth are often more vulnerable than others.

Land degradation in the form of soil carbon loss is estimated to have been ongoing for at least 12,000 years, but increased exponentially in the last 200 years (Sanderman et al. 2017912). Before the advent of modern sources of nutrients, it was imperative for farmers to maintain and improve soil fertility through the prevention of runoff and erosion, and management of nutrients through vegetation residues and manure. Many ancient farming systems were sustainable for hundreds and even thousands of years, such as raised-field agriculture in Mexico (Crews and Gliessman 1991913), tropical forest gardens in Southeast Asia and Central America (Ross 2011914; Torquebiau 1992915; Turner and Sabloff 2012916), terraced agriculture in East Africa, Central America, Southeast Asia and the Mediterranean basin (Turner and Sabloff 2012917; Preti and Romano 2014918; Widgren and Sutton 2004919; Håkansson and Widgren 2007920; Davies and Moore 2016921; Davies 2015922), and integrated rice-fish cultivation in East Asia (Frei and Becker 2005923).

Such long-term sustainable farming systems evolved in very different times and geographical contexts, but they share many common features, such as: the combination of species and structural diversity in time and space (horizontally and vertically) in order to optimise the use of available land; recycling of nutrients through biodiversity of plants, animals and microbes; harnessing the full range of site-specific micro-environments (e.g., wet and dry soils); biological interdependencies which help suppression of pests; reliance on mainly local resources; reliance on local varieties of crops, and sometimes incorporation of wild plants and animals; the systems are often labour and knowledge intensive (Rudel et al. 2016924; Beets 1990925; Netting 1993926; Altieri and Koohafkan 2008927). Such farming systems have stood the test of time and can provide important knowledge for adapting farming systems to climate change (Koohafkann and Altieri 2011928).

In modern agriculture, the importance of maintaining the biological productivity and ecological integrity of farmland has not been a necessity in the same way as in pre-modern agriculture because nutrients and water have been supplied externally. The extreme land degradation in the US Midwest during the Dust Bowl period in the 1930s became an important wake-up call for agriculture and agricultural research and development, from which we can still learn much in order to adapt to ongoing and future climate change (McLeman et al. 2014929; Baveye et al. 2011930; McLeman and Smit 2006931).

SLM is a unifying framework for addressing land degradation and can be defined as the stewardship and use of land resources, including soils, water, animals and plants, to meet changing human needs, while simultaneously ensuring the long-term productive potential of these resources and the maintenance of their environmental functions. It is a comprehensive approach comprising technologies combined with social, economic and political enabling conditions (Nkonya et al. 2011932). It is important to stress that farming systems are informed by both scientific and local/traditional knowledge. The power of SLM in small-scale diverse farming was demonstrated effectively in Nicaragua after the severe cyclone Mitch in 1998 (Holt-Giménez 2002933). Pairwise analysis of 880 fields with and without implementation of SLM practices showed that the SLM fields systematically fared better than the fields without SLM in terms of more topsoil remaining, higher field moisture, more vegetation, less erosion and lower economic losses after the cyclone. Furthermore, the difference between fields with and without SLM increased with increasing levels of storm intensity, slope gradient, and age of SLM (Holt-Giménez 2002934).

When addressing land degradation through SLM and other approaches, it is important to consider feedbacks that impact on climate change. Table 4.2 shows some of the most important land degradation issues, their potential solutions, and their impacts on climate change. This table provides a link between the comprehensive lists of land degradation processes (Table 4.1) and land management solutions.

Table 4.2

Interaction of human and climate drivers can exacerbate desertification and land degradation.

Implementation of SLM practices has been shown to increase the productivity of land (Branca et al. 2013941) and to provide good economic returns on investment in many different settings around the world (Mirzabaev et al. 2015942). Giger et al. (2018)943 showed, in a meta study of 363 SLM projects over the period 1990 to 2012, that 73% of the projects were perceived to have a positive or at least neutral cost-benefit ratio in the short term, and 97% were perceived to have a positive or very positive cost-benefit ratio in the long term ( robust evidence, high agreement). Despite the positive effects, uptake is far from universal. Local factors, both biophysical conditions (e.g., soils,

drainage, and topography) and socio-economic conditions (e.g., land tenure, economic status, and land fragmentation) play decisive roles in the interest in, capacity to undertake, and successful implementation of SLM practices (Teshome et al. 2016944; Vogl et al. 2017945; Tesfaye et al. 2016946; Cerdà et al. 2018947; Adimassu et al. 2016948). From a landscape perspective, SLM can generate benefits, including adaptation to and mitigation of climate change, for entire watersheds, but challenges remain regarding coordinated and consistent implementation ( medium evidence, medium agreement) (Kerr et al. 2016949; Wang et al. 2016a950).

Climate change impacts on land degradation can be avoided, reduced or even reversed, but need to be addressed in a context-sensitive manner. Many of the responses described in this section can also provide synergies of adaptation and mitigation. In this section we provide more in-depth analysis of a number of salient aspects of how land degradation and climate change interact. Table 4.3 is a synthesis of how of these case studies relate to climate change and other broader issues in terms of co-benefits.

Table 4.3

Synthesis of how the case studies interact with climate change and a broader set of co-benefits.

Such degradation takes the form of high soil salinity, inundation and waterlogging, erosion and freshwater contamination. The interannual variability of precipitation with flooding conditions in some years and drought conditions in others has caused variable river flows and sediment runoff below Kotri Barrage (about 200 km upstream of the Indus delta). This has affected hydrological processes in the lower reaches of the river and the delta, contributing to the degradation (Rasul et al. 20121657).

Over 480,000 ha of fertile land is now affected by sea water intrusion, wherein eight coastal subdivisions of the districts of Badin and Thatta are mostly affected (Chandio et al. 20111658). A very high intrusion rate of 0.179 ± 0.0315 km yr⁻¹, based on the analysis of satellite data, was observed in the Indus delta during the 10 years between 2004 and 2015 (Kalhoro et al. 20161522). The area of agricultural crops under cultivation has been declining, with economic losses of millions of USD (IUCN 20031523). Crop yields have reduced due to soil salinity, in some places failing entirely. Soil salinity varies seasonally, depending largely on the river discharge: during the wet season (August 2014), salinity (0.18 mg L ⁻¹) reached 24 km upstream, while during the dry season (May 2013), it reached 84 km upstream (Kalhoro et al. 20161524). The freshwater aquifers have also been contaminated with sea water, rendering them unfit for drinking or irrigation purposes. Lack of clean drinking water and sanitation causes widespread diseases, of which diarrhoea is most common (IUCN 20031525).

Lake Urmia in northwest Iran, the second-largest saltwater lake in the world and the habitat for endemic Iranian brine shrimp, Artemia urmiana, has also been affected by salty water intrusion. During a 17- year period between 1998 and 2014, human disruption, including agriculture and years of dam building affected the natural flow of freshwater as well as salty sea water in the surrounding area of Lake Urmia. Water quality has also been adversely affected, with salinity fluctuating over time, but in recent years reaching a maximum of 340 g L ⁻¹ (similar to levels in the Dead Sea). This has rendered the underground water unfit for drinking and agricultural purposes and risky to human health and livelihoods. Adverse impacts of global climate change as well as direct human impacts have caused changes in land use, overuse of underground water resources and construction of dams over rivers, which resulted in the drying-up of the lake in large part. This condition created sand, dust and salt storms in the region which affected many sectors including agriculture, water resources, rangelands, forests and health, and generally presented desertification conditions around the lake (Karbassi et al. 20101526; Marjani and Jamali 20141527; Shadkam et al. 20161528).

Rapid irrigation expansion in the basin has, however, indirectly contributed to inflow reduction. Annual inflow to Lake Urmia has dropped by 48% in recent years. About three-fifths of this change was caused by climate change and two-fifths by water resource development and agriculture (Karbassi et al. 20101529; Marjani and Jamali 20141530; Shadkam et al. 20161531).

In other countries, intrusion of seawater is exacerbated by destruction of mangrove forests. Mangroves are important coastal ecosystems that provide spawning bed for fish, timber for building, and livelihoods to dependent communities. They also act as barriers against coastal erosion, storm surges, tropical cyclones and tsunamis (Kalhoro et al. 20171537) and are among the most carbon-rich stocks on Earth (Atwood et al. 20171538). They nevertheless face a variety of threats: climatic (storm surges, tidal activities, high temperatures) and human (coastal developments, pollution, deforestation, conversion to aquaculture, rice culture, oil palm plantation), leading to declines in their areas. In Pakistan, using remote sensing, the mangrove forest cover in the Indus delta decreased from 260,000 ha in 1980s to 160,000 ha in 1990 (Chandio et al. 20111539). Based on remotely sensed data, a sharp decline in the mangrove area was also found in the arid coastal region of Hormozgan province in southern Iran during 1972, 1987 and 1997 (Etemadi et al. 20161540). Myanmar has the highest rate (about 1% yr ⁻¹) of mangrove deforestation in the world (Atwood et al. 2017). Regarding global loss of carbon stored in the mangrove due to deforestation, four countries exhibited high levels of loss: Indonesia (3410 GgCO ₂ yr ⁻¹), Malaysia (1288 GgCO ₂ yr ⁻¹), US (206 GgCO ₂ yr ⁻¹) and Brazil (186 GgCO ₂ yr ⁻¹). Only in Bangladesh and Guinea Bissau was there no decline in the mangrove area from 2000 to 2012 (Atwood et al. 20171541).

Frequency and intensity of average tropical cyclones will continue to increase (Knutson et al. 20151543) and global sea level will continue to rise. The IPCC (2013)1544 projected with medium confidence that the sea level in the Asia Pacific region will rise from 0.4 to 0.6 m, depending on the emission pathway, by the end of this century. Adaptation measures are urgently required to protect the world's coastal areas from further degradation due to saline intrusion. A viable policy framework is needed to ensure that the environmental flows to deltas in order to repulse the intruding seawater.

The co-benefits of improved land management, such as mitigation of climate change, increased climate resilience of agriculture, and impacts on rural areas/societies are well known in theory, but there is a lack of a coherent and systematic global inventory of such integrated efforts. Both successes and failures are important to document systematically.

Efforts to reduce climate change through land-demanding mitigation actions aimed at removing atmospheric carbon, such as afforestation, reforestation, bioenergy crops, intensification of land management and plantation forestry can adversely affect land conditions and lead to degradation. However, they may also lead to avoidance, reduction and reversal of degradation. Regionally differentiated, socially and ecologically appropriate SLM strategies need to be identified, implemented, monitored and the results communicated widely to ensure climate effective outcomes.

Impacts of new technologies on land degradation and their social and economic ramifications need more research.

Improved quantification of the global extent, severity and rates of land degradation by combining remote sensing with a systematic use of ancillary data is a priority. The current attempts need better scientific underpinning and appropriate funding.

Land degradation is defined using multiple criteria but the definition does not provide thresholds or the magnitude of acceptable change. In practice, human interactions with land will result in a variety of changes; some may contribute positively to one criterion while adversely affecting another. Research is required on the magnitude of impacts and the resulting trade-offs. Given the urgent need to remove carbon from the atmosphere and to reduce climate change impacts, it is important to reach agreement on what level of reduction in one criterion (biological productivity, ecological integrity) may be acceptable for a given increase in another criterion (ecological integrity, biological productivity).

Attribution of land degradation to the underlying drivers is a challenge because it is a complex web of causality rather than a simple cause-effect relationship. Also, diverging views on land degradation in relation to other challenges is hampering such efforts.

A more systematic treatment of the views and experiences of land users would be useful in land degradation studies.

Much research has tried to understand how social and ecological systems are affected by a particular stressor, for example, drought, heat, or waterlogging. But less research has tried to understand how such systems are affected by several simultaneous stressors - which is more realistic in the context of climate change (Mittler 20061).

More realistic modelling of carbon dynamics, including better appreciation of below-ground biota, would help us to better quantify the role of soils and soil management for soil carbon sequestration.

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Land degradation affects people and ecosystems throughout the planet and is both affected by climate change and contributes to it. In this report, land degradation is defined as a negative trend in land condition, caused by direct or indirect human-induced processes including anthropogenic climate change, expressed as long-term reduction or loss of at least one of the following: biological productivity, ecological integrity, or value to humans.

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Multi year soil enrichment project by farmers in Colorado findings

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Multi year soil enrichment project by farmers in Colorado findings

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Primary document to use for projects

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Final report for FW19-341 - SARE Grant Management System

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OUR GRANT’S QUESTION WAS: Does providing annual soil health testing, education and team-building lead to broader adoption of practices which improve soil health?
3 YEARS LATER, OUR ANSWER IS: “Yes, for some growers, BUT………”

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https://www.youtube.com/watch?v=NJhpoYwAqFA

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African perspective on climate-smart agriculture

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African perspective on climate-smart agriculture

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Excellent. 5'. will use. Includes food, water and carbon capture all in Africa.

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Climate-Smart Agriculture: Helping the World Produce More Food