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answer key can be found in the message board for Science 

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answer key can be found in the message board for Science 

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Conservation biology studies the nature and status of Earth's biological diversity with the aim of protecting species and their habitats from excessive extinction rates that are caused by human actions

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Conservation biology studies the nature and status of Earth's biological diversity with the aim of protecting species and their habitats from excessive extinction rates that are caused by human actions

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A disturbance, such as a wild fire, destroys the forest ... Dynamics in secondary succession are strongly influenced by pre-disturbance conditions

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A disturbance, such as a wild fire, destroys the forest ... Dynamics in secondary succession are strongly influenced by pre-disturbance conditions

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the act of interrupting, changing the arrangement of, or upsetting : the state of being interrupted, changed in arrangement, or upset Fish can feel any disturbances in the water. 

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the act of interrupting, changing the arrangement of, or upsetting : the state of being interrupted, changed in arrangement, or upset Fish can feel any disturbances in the water. 

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Ecological succession, is the process by which a specific ecology has more or less orderly and predictably changed after a disturbance like a fire. In long-term studies, there is a species succession process in the way forests develop.

Primary, secondary and cyclic succession

Successional dynamics beginning with colonization of an area that has not been previously occupied by an ecological community, such as newly exposed rock or sand surfaces, lava flows, newly exposed glacial tills, etc., are referred to as primary succession. The stages of primary succession include pioneer plants (lichens and mosses), grassy stage, smaller shrubs, and trees. Animals begin to return when there is food there for them to eat. When it is a fully functioning ecosystem, it has reached the climax community stage. For example, parts of Acadia National Park in Maine went through primary succession.

Successional dynamics following severe disturbance or removal of a pre-existing community are called secondary succession. Dynamics in secondary succession are strongly influenced by pre-disturbance conditions, including soil development, seed banks, remaining organic matter, and residual living organisms. Because of residual fertility and pre-existing organisms, community change in early stages of secondary succession can be relatively rapid. In a fragmented old field habitat created in eastern Kansas, woody plants "colonized more rapidly (per unit area) on large and nearby patches."

Secondary succession is much more commonly observed and studied than primary succession. Particularly common types of secondary succession include responses to natural disturbances such as fire, flood, and severe winds, and to human-caused disturbances such as logging and agriculture. As an example, secondary succession has been occurring in Shenandoah National Park following the 1995 flood of the Mormon River, which destroyed plant and animal life. Today, plant and animal species are beginning to return.

Seasonal and cyclic dynamics

Unlike secondary succession, these types of vegetation change are not dependent on disturbance but are periodic changes arising from fluctuating species interactions or recurring events. These models modify the climax concept towards one of dynamic states.

Causes of plant succession

Autogenic succession can be brought by changes in the soil caused by the organisms there. These changes include accumulation of organic matter in litter or humic layer, alteration of soil nutrients, change in pH of soil by plants growing there. The structure of the plants themselves can also alter the community. For example, when larger species like trees mature, they produce shade on to the developing forest floor that tends to exclude light-requiring species. Shade-tolerant species will invade the area.

Allogenic succession is caused by external environmental influences and not by the vegetation. For example, soil changes due to erosion, leaching or the deposition of silt and clays can alter the nutrient content and water relationships in the ecosystems. Animals also play an important role in allogenic changes as they are pollinators, seed dispersers and herbivores. They can also increase nutrient content of the soil in certain areas, or shift soil about (as termites, ants, and moles do) creating patches in the habitat. This may create regeneration sites that favor certain species.

Climatic factors may be very important, but on a much longer time-scale than any other. Changes in temperature and rainfall patterns will promote changes in communities. As the climate warmed at the end of each ice age, great successional changes took place. The tundra vegetation and bare glacial till deposits underwent succession to mixed deciduous forest. The greenhouse effect resulting in increase in temperature is likely to bring profound Allogenic changes in the next century. Geological and climatic catastrophes such as volcanic eruptions, earthquakes, avalanches, meteors, floods, fires, and high wind also bring allogenic changes.

Mechanisms

In 1916, Frederic Clements published a descriptive theory of succession and advanced it as a general ecological concept. His theory of succession had a powerful influence on ecological thought. Clements' concept is usually termed classical ecological theory. According to Clements, succession is a process involving several phases:

1. Nudation: Succession begins with the development of a bare site, called Nudation (disturbance).

2. Migration: It refers to arrival of propagules.

3. Ecesis: It involves establishment and initial growth of vegetation.

4. Competition: As vegetation becomes well established, grow, and spread, various species begin to compete for space, light and nutrients.

5. Reaction: During this phase autogenic changes such as the buildup of humus affect the habitat, and one plant community replaces another.

6. Stabilization: A supposedly stable climax community forms.

Seral communities

A seral community is an intermediate stage found in an ecosystem advancing towards its climax community. In many cases more than one seral stage evolves until climax conditions are attained. A prisere is a collection of seres making up the development of an area from non-vegetated surfaces to a climax community. Depending on the substratum and climate, different seres are found.

Changes in animal life

Succession theory was developed primarily by botanists. The study of succession applied to whole ecosystems initiated in the writings of Ramon Margalef, while Eugene Odum's publication of The Strategy of Ecosystem Development is considered its formal starting point.

Animal life also exhibit changes with changing communities. In lichen stage the fauna is sparse. It comprises few mites, ants and spiders living in the cracks and crevices. The fauna undergoes a qualitative increase during herb grass stage. The animals found during this stage include nematodes, insects larvae, ants, spiders, mites, etc. The animal population increases and diversifies with the development of forest climax community. The fauna consists of invertebrates like slugs, snails, worms, millipedes, centipedes, ants, bugs; and vertebrates such as squirrels, foxes, mice, moles, snakes, various birds, salamanders and frogs.

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Ecological succession, is the process by which a specific ecology has more or less orderly and predictably changed after a disturbance like a fire. In long-term studies, there is a species succession process in the way forests develop.

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An ecological footprint measures how much people take from nature. The footprint is then compared to the amount of natural resources nature can renew.

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An ecological footprint measures how much people take from nature. The footprint is then compared to the amount of natural resources nature can renew.

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A natural resource is what people can use which comes from the natural environment. Examples of natural resources are air, water, wood, oil, ...

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A natural resource is what people can use which comes from the natural environment. Examples of natural resources are air, water, wood, oil, ...

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The addition of any substance to an area that harms the living organisms in that area.... Air pollution · Water pollution · Noise pollution · Soil pollution or land pollution · Plastic pollution · Thermal pollution · Effects Human health Environment 

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The addition of any substance to an area that harms the living organisms in that area.... Air pollution · Water pollution · Noise pollution · Soil pollution or land pollution · Plastic pollution · Thermal pollution · Effects Human health Environment 

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Pollution is when something is added to the environment that is harmful or poisonous to living things. There are four main types of pollution: air, water, noise, and soil or land pollution. Smoke or dust in the air is a type of pollution because it is bad for the lungs when we breathe in. Sewage in drinking water is another type of pollution. It can make people ill because it contains germs and viruses. People living next to a building site where there is too much noise can become sick because of a lack of sleep. Dangerous chemicals can seep into soil from litter and other man-made chemicals.

As pollution grows, ways to combat it have grown, too. Solar energy and wind energy give people other ways to power their homes. When people use these alternative forms of energy, they put less carbon dioxide into the environment.

Air pollution

Air pollution is caused by poisonous gases, sulphur dioxide, nitrogen dioxide, carbon monoxide, and very small particulates. It is also caused by the smoke and harmful gases released by the fires that make vehicles and factories go. Use of coal, wood, and kerosene as fuels for fire also causes air pollution. Air pollution may cause breathing problems such as asthma or other health problems. It also causes diseases like cancer.

Air pollution causes global warming and acid rain. It results in increased temperatures, erratic rains, and drought worldwide. This makes it difficult for living organisms to survive.

Water pollution

Water pollution is the presence of harmful materials in water, such as sewage, dissolved metals, waste from farms or factories, and crude oil spilled from oil tankers. The three main substances that pollute water are nitrates from fertilizers, sewage, and detergents.

Activities such as bathing and washing clothes near lakes, ponds, or rivers add nutrients like nitrogen and phosphorous into water. This leads to the growth of too much algae on the surface of the water. This algae blocks the penetration of sunlight and air into the water.

Pollution causes harm to organisms living in water and can also harm people's health. In extreme cases, it may cause problems such as cancer.

Noise pollution

Noise pollution, also known as sound pollution, is noise that is harmful to humans and animals. This includes the sound of vehicles, loudspeakers, etc. Noise pollution can cause ear problems or even permanent deafness, especially in older people.

Soil pollution or land pollution

Soil pollution (also known as land pollution) is when man-made chemicals, such as hydrocarbons, heavy metals, or solvents get into the soil. These chemicals come from industrial activities and poor waste management. Soil pollution may cause health risks. The chemicals can produce harmful vapors, or they can contaminate water supplies underneath the polluted soil.

Plastic pollution

Plastic pollution is the collection of plastic products in the environment that negatively affects wildlife, wildlife habitat, or humans.

Human health

Bad air quality can kill many organisms, including humans. Ozone pollution can cause respiratory disease, cardiovascular disease, throat inflammation, chest pain, and congestion. A 2010 analysis estimated that 1.2 million people died prematurely each year in China because of air pollution. The high smog levels China has been facing for a long time can do damage to civilians' bodies and cause diseases. The WHO estimated in 2007 that air pollution causes half a million deaths per year in India. Studies have estimated that the number of people killed each year in the United States could be over 50,000.

Water pollution causes approximately 14,000 deaths per day, mostly in developing countries. In these countries, water is contaminated by untreated sewage. An estimated 500 million Indians have no access to a proper toilet. Over ten million people in India fell ill with waterborne illnesses in 2013, and 1,535 people died, most of them children. Nearly 500 million Chinese do not have access to safe drinking water.

Oil spills can cause skin irritations and rashes.

Noise pollution can cause hearing loss, high blood pressure, stress, and sleep disturbance.

The ingestion of Mercury has been linked to developmental deficits in children and neurologic symptoms.

Older people are exposed to diseases induced by air pollution. Those with heart or lung disorders are at additional risk. Children and infants are also at serious risk. Lead and other heavy metals have been shown to cause neurological problems. Chemical and radioactive substances can cause cancer and as well as birth defects.

An October 2017 study by the Lancet Commission on Pollution and Health found that global pollution, specifically toxic air, water, soils, and workplaces, kill nine million people annually.

Environment

Pollution is present widely in the environment. There are several effects of this:

Pollution control

Pollution control is a term used in environmental management. It means the control of emissions and effluents into air, water, or soil. Without pollution control, the waste products from overconsumption, heating, agriculture, mining, manufacturing, transportation, and other human activities could degrade the environment. It is believed that pollution prevention and waste minimization are better than pollution control.

Pollution control devices

Air pollution control

Dust collection systems

Scrubbers

Baffle spray scrubber

Cyclonic spray scrubber

Ejector venturi scrubber

Mechanically aided scrubber

Spray tower

Wet scrubber

Sewage treatment

Sedimentation (Primary treatment)

Activated sludge biotreaters (Secondary treatment; also used for industrial wastewater)

Aerated lagoons

Constructed wetlands (also used for urban runoff)

Industrial wastewater treatment

API oil-water separators

Biofilters

Dissolved air flotation (DAF)

Powdered activated carbon treatment

Ultrafiltration

Vapor recovery systems

Phytoremediation

Interesting facts about pollution

Cleanups can save animals' lives and discourage people from littering in the future.

People who live in places with high levels of air pollutants have a 20% higher risk of death from lung cancer than people who live in less polluted areas.

Plants can filter air pollution.

There are more than 73 kinds of pesticides in groundwater that is used as drinking water.

Approximately 40% of the lakes in America are too polluted for fishing, aquatic life, or swimming.

In 1975, the National Academy of Sciences estimated that cargo ships and cruise liners had dumped 14 billion pounds of garbage into the ocean.

Homeowners use chemicals that are 10 times more toxic per acre than the amount used by the farmers.

In the U.S., 41% of all insecticides are used on corn. Eighty percent of these are used to treat a pest that could be controlled simply by rotating the corn for one year with any other crop.

Americans buy more than 29 million bottles of water every year. Only 13% of these bottles are recycled every year.

Recycling and compostng have become more popular. They prevented 85 million tons of material away from being disposed of in 2010, up from 18 million tons in 1980.

Noise pollution is the most ignored type of pollution.

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In Spanish: Contaminación para niños

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able to be maintained at a certain rate or level.  The study of ecology believes that sustainability is achieved through the balance of species and the resources within their environment. 

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able to be maintained at a certain rate or level.  The study of ecology believes that sustainability is achieved through the balance of species and the resources within their environment. 

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Sustainability means that a process or state can be maintained at a certain level for as long as is wanted. In the 21st century, it refers generally to how the Earth and humans can co-exist.

The study of ecology believes that sustainability is achieved through the balance of species and the resources within their environment. To maintain this equilibrium, available resources must not be depleted faster than resources are naturally generated.

Healthy ecosystems and environments are necessary to the survival of humans and other organisms. Ways of reducing negative human impact are environmentally-friendly chemical engineering, environmental resources management and environmental protection. Information is gained from green computing, green chemistry, earth science, environmental science and conservation biology. Ecological economics studies the fields of academic research that aim to address human economies and natural ecosystems.

Ways of living more sustainably can take many forms from reorganizing living conditions (e.g., ecovillages, eco-municipalities and sustainable cities), reappraising economic sectors ( permaculture, green building, sustainable agriculture), or work practices (sustainable architecture), using science to develop new technologies (green technologies, renewable energy and sustainable fission and fusion power), or designing systems in a flexible and reversible manner, and adjusting individual lifestyles that conserve natural resources.

Despite the increased popularity of the use of the term "sustainability", the possibility that human societies will achieve environmental sustainability has been, and continues to be, questioned-in light of environmental degradation, climate change, overconsumption, population growth and societies' pursuit of unlimited economic growth in a closed system.

Environmental dimension

Healthy ecosystems provide vital goods and services to humans and other organisms. There are two major ways of reducing negative human impact and enhancing ecosystem services and the first of these is environmental management. This direct approach is based largely on information gained from earth science, environmental science and conservation biology.

Environmental management

At the global scale and in the broadest sense environmental management involves the oceans, freshwater systems, land and atmosphere, it can also be equally applied to any ecosystem from a tropical rainforest to a home garden.

Atmosphere

Management of the global atmosphere now involves assessment of all aspects of the carbon cycle to identify opportunities to address human-induced climate change and this has become a major focus of scientific research because of the potential catastrophic effects on biodiversity and human communities.

Other human impacts on the atmosphere include the air pollution in cities, the pollutants including toxic chemicals like nitrogen oxides, sulfur oxides, volatile organic compounds and particulate matter that produce photochemical smog and acid rain, and the chlorofluorocarbons that degrade the ozone layer.

Freshwater and oceans

Water covers 71% of the Earth's surface. Of this, 97.5% is the salty water of the oceans and only 2.5% freshwater, most of which is locked up in the Antarctic ice sheet. The remaining freshwater is found in glaciers, lakes, rivers, wetlands, the soil, aquifers and atmosphere. Due to the water cycle, fresh water supply is continually replenished by precipitation, however there is still a limited amount necessitating management of this resource.

Awareness of the global importance of preserving water for ecosystem services has only recently emerged as, during the 20th century, more than half the world's wetlands have been lost along with their valuable environmental services. Increasing urbanization pollutes clean water supplies and much of the world still does not have access to clean, safe water. Greater emphasis is now being placed on the improved management of blue (harvestable) and green (soil water available for plant use) water, and this applies at all scales of water management.

Ocean circulation patterns have a strong influence on climate and weather and, in turn, the food supply of both humans and other organisms. Scientists have warned of the possibility, under the influence of climate change, of a sudden alteration in circulation patterns of ocean currents that could drastically alter the climate in some regions of the globe. Ten per cent of the world's population - about 600 million people - live in low-lying areas vulnerable to sea level rise.

Loss of biodiversity stems largely from the habitat loss. Land use change is fundamental to the operations of the biosphere because alterations in the relative proportions of land dedicated to urbanisation, agriculture, forest, woodland, grassland and pasture have a marked effect on the global water, carbon and nitrogen biogeochemical cycles and this can impact negatively on both natural and human systems. At the local human scale, major sustainability benefits accrue from sustainable parks and gardens and green cities.

Food is essential to life. Feeding more than six billion human bodies takes a heavy toll on the Earth's resources. Environmental problems associated with industrial agriculture and agribusiness are now being addressed through such movements as sustainable agriculture, organic farming and more sustainable business practices.

Management of human consumption

The underlying driver of direct human impacts on the environment is human consumption. This impact is reduced by not only consuming less but by also making the full cycle of production, use and disposal more sustainable.

Key resource categories relating to human needs are food, energy, materials and water.

The Sun's energy, stored by plants ( primary producers) during photosynthesis, passes through the food chain to other organisms to ultimately power all living processes.

Since the industrial revolution the concentrated energy of the Sun stored in fossilized plants as fossil fuels has been a major driver of technology which, in turn, has been the source of both economic and political power. In 2007 climate scientists of the IPCC concluded that there was at least a 90% probability that atmospheric increase in CO ₂ was human-induced, mostly as a result of fossil fuel emissions but, to a lesser extent from changes in land use. Stabilizing the world's climate will require high-income countries to reduce their emissions by 60-90%.

Reducing greenhouse emissions, is being tackled at all scales, ranging from tracking the passage of carbon through the carbon cycle to the commercialization of renewable energy, developing less carbon-hungry technology and transport systems and attempts by individuals to lead carbon neutral lifestyles by monitoring the fossil fuel use embodied in all the goods and services they use.

Water security and food security are inextricably linked. In the decade 1951-60 human water withdrawals were four times greater than the previous decade. This rapid increase resulted from scientific and technological developments impacting through the economy - especially the increase in irrigated land, growth in industrial and power sectors, and intensive dam construction on all continents. This altered the water cycle of rivers and lakes, affected their water quality and had a significant impact on the global water cycle.

Currently towards 35% of human water use is unsustainable, drawing on diminishing aquifers and reducing the flows of major rivers: this percentage is likely to increase if climate change impacts become more severe, populations increase, aquifers become progressively depleted and supplies become polluted and unsanitary.

Water efficiency is being improved on a global scale by increased demand management, improved infrastructure, improved water productivity of agriculture, minimising the water intensity (embodied water) of goods and services, addressing shortages in the non-industrialised world, concentrating food production in areas of high productivity, and planning for climate change. At the local level, people are becoming more self-sufficient by harvesting rainwater and reducing use of mains water.

The American Public Health Association (APHA) defines a "sustainable food system" as "one that provides healthy food to meet current food needs while maintaining healthy ecosystems that can also provide food for generations to come with minimal negative impact to the environment. A sustainable food system also encourages local production and distribution infrastructures and makes nutritious food available, accessible, and affordable to all. Further, it is humane and just, protecting farmers and other workers, consumers, and communities."

Concerns about the environmental impacts of agribusiness and the stark contrast between the obesity problems of the Western world and the poverty and food insecurity of the developing world have generated a strong movement towards healthy, sustainable eating as a major component of overall ethical consumerism. The environmental effects of different dietary patterns depend on many factors, including the proportion of animal and plant foods consumed and the method of food production.

A Mediterranean diet is recommended which is associated with health and longevity and is low in meat, rich in fruits and vegetables, low in added sugar and limited salt, and low in saturated fatty acids; the traditional source of fat in the Mediterranean is olive oil, rich in monounsaturated fat. The healthy rice-based Japanese diet is also high in carbohydrates and low in fat. Both diets are low in meat and saturated fats and high in legumes and other vegetables; they are associated with a low incidence of ailments and low environmental impact.

At the global level the environmental impact of agribusiness is being addressed through sustainable agriculture and organic farming. At the local level there are various movements working towards local food production, more productive use of urban wastelands and domestic gardens including permaculture, urban horticulture, local food, slow food, sustainable gardening, and organic gardening.

Sustainable seafood is seafood from either fished or farmed sources that can maintain or increase production in the future without jeopardizing the ecosystems from which it was acquired. The sustainable seafood movement has gained momentum as more people become aware about both overfishing and environmentally-destructive fishing methods.

Materials, toxic substances, waste

As global population and affluence has increased, so has the use of various materials increased in volume, diversity and distance transported. Included here are raw materials, minerals, synthetic chemicals (including hazardous substances), manufactured products, food, living organisms and waste. By 2050, humanity could consume an estimated 140 billion tons of minerals, ores, fossil fuels and biomass per year (three times its current amount) unless the economic growth rate is decoupled from the rate of natural resource consumption. Developed countries' citizens consume an average of 16 tons of those four key resources per capita (ranging up to 40 or more tons per person in some developed countries with resource consumption levels far beyond what is likely sustainable.

Sustainable use of materials has targeted the idea of dematerialization, converting the linear path of materials (extraction, use, disposal in landfill) to a circular material flow that reuses materials as much as possible, much like the cycling and reuse of waste in nature. This approach is supported by product stewardship and the increasing use of material flow analysis at all levels, especially individual countries and the global economy. The use of sustainable biomaterials that come from renewable sources and that can be recycled is preferred to the use on non-renewables from a life cycle standpoint.

Synthetic chemical production has escalated following the stimulus it received during the second World War. Chemical production includes everything from herbicides, pesticides and fertilizers to domestic chemicals and hazardous substances. Apart from the build-up of greenhouse gas emissions in the atmosphere, chemicals of particular concern include: heavy metals, nuclear waste, chlorofluorocarbons, persistent organic pollutants and all harmful chemicals capable of bioaccumulation. Although most synthetic chemicals are harmless there needs to be rigorous testing of new chemicals, in all countries, for adverse environmental and health effects. International legislation has been established to deal with the global distribution and management of dangerous goods.

Every economic activity produces material that can be classified as waste. To reduce waste industry, business and government are now mimicking nature by turning the waste produced by industrial metabolism into resource. Dematerialization is being encouraged through the ideas of industrial ecology, ecodesign and ecolabelling. In addition to the well-established "reduce, reuse and recycle," shoppers are using their purchasing power for ethical consumerism.

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Changes in environmental conditions lead to coral bleaching and harm to biodiversity of fragile marine ecosystems.

In Spanish: Sostenibilidad para niños

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the force exerted by a growing population upon its environment, resulting in dispersal or reduction of the population.

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the force exerted by a growing population upon its environment, resulting in dispersal or reduction of the population.