Left: ecosystems are highly marine systems., right: on the in.An ecosystem is a of living organisms in conjunction with the of their environment, interacting as a. These and are linked together through nutrient cycles and energy flows.

Energy enters the system through and is incorporated into plant tissue. By feeding on plants and on one-another, animals play an important role in the movement of and through the system. They also influence the quantity of plant and present. By breaking down dead, release carbon back to the atmosphere and facilitate by converting nutrients stored in dead biomass back to a form that can be readily used by plants and other microbes.Ecosystems are controlled by external and internal. External factors such as, which forms the soil and, control the overall structure of an ecosystem but are not themselves influenced by the ecosystem.

Unlike external factors, internal factors are controlled, for example, decomposition, root competition, shading, disturbance, succession, and the types of species present.Ecosystems are entities—they are subject to periodic disturbances and are in the process of recovering from some past disturbance. Ecosystems in similar environments that are located in different parts of the world can end up doing things very differently simply because they have different pools of species present. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to.Resource inputs are generally controlled by external processes like climate and parent material. Resource availability within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Although humans operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.affects ecosystem functioning, as do the processes of.

Ecosystems provide a variety of upon which people depend. Contents.HistoryThe term ecosystem was first used in 1935 in a publication by British ecologist.

Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment. He later refined the term, describing it as 'The whole system.

Learn what an ecosystem is, how energy and matter move through ecosystems, and what makes an ecosystem stable. Learn what an ecosystem is, how energy and matter move through ecosystems, and what makes an ecosystem stable. If you're seeing this message, it means we're having trouble loading external resources on our website. Ecosystems are controlled both by external and internal factors. External factors, also called state factors, control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem.

Including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment'. Tansley regarded ecosystems not simply as natural units, but as 'mental isolates'. Tansley later defined the spatial extent of ecosystems using the term., a who was a contemporary of Tansley's, combined 's ideas about ecology with those of Russian geochemist.

As a result, he suggested that mineral nutrient availability in a lake limited. This would, in turn, limit the abundance of animals that feed on algae. Took these ideas further to suggest that the flow of energy through a lake was the primary driver of the ecosystem. Hutchinson's students, brothers and, further developed a 'systems approach' to the study of ecosystems.

This allowed them to study the flow of energy and material through ecological systems. Biomes of the worldEcosystems are controlled both by external and internal factors. External factors, also called state factors, control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. The most important of these is.

Climate determines the in which the ecosystem is embedded. Rainfall patterns and seasonal temperatures influence photosynthesis and thereby determine the amount of water and energy available to the ecosystem.determines the nature of the soil in an ecosystem, and influences the supply of mineral nutrients. Also controls ecosystem processes by affecting things like, soil development and the movement of water through a system. For example, ecosystems can be quite different if situated in a small depression on the landscape, versus one present on an adjacent steep hillside.Other external factors that play an important role in ecosystem functioning include time and potential. Similarly, the set of organisms that can potentially be present in an area can also significantly affect ecosystems.

Ecosystems in similar environments that are located in different parts of the world can end up doing things very differently simply because they have different pools of species present. The can cause substantial shifts in ecosystem function.Unlike external factors, internal factors in ecosystems not only control ecosystem processes but are also controlled by them. Consequently, they are often subject to.

While the inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other factors like disturbance, succession or the types of species present are also internal factors.Primary production.

Main article:Primary production is the production of from inorganic carbon sources. This mainly occurs through. The energy incorporated through this process supports life on earth, while the carbon makes up much of the organic matter in living and dead biomass,. It also drives the, which influences global via the.Through the process of photosynthesis, plants capture energy from light and use it to combine and water to produce. The photosynthesis carried out by all the plants in an ecosystem is called the gross primary production (GPP). About half of the GPP is consumed in plant respiration.

The remainder, that portion of GPP that is not used up by respiration, is known as the (NPP). Total photosynthesis is limited by a range of environmental factors. These include the amount of light available, the amount of area a plant has to capture light (shading by other plants is a major limitation of photosynthesis), rate at which carbon dioxide can be supplied to the to support photosynthesis, the availability of water, and the availability of suitable temperatures for carrying out. See also: andand enter ecosystems through, are incorporated into living tissue, transferred to other organisms that feed on the living and dead plant matter, and eventually released through respiration.The carbon and energy incorporated into plant tissues (net primary production) is either consumed by animals while the plant is alive, or it remains uneaten when the plant tissue dies and becomes. In, roughly 90% of the net primary production ends up being broken down.

The remainder is either consumed by animals while still alive and enters the plant-based trophic system, or it is consumed after it has died, and enters the detritus-based trophic system. In, the proportion of plant biomass that gets consumed by is much higher.In trophic systems photosynthetic organisms are the primary producers. The organisms that consume their tissues are called primary consumers or —.

Organisms which feed on ( and ) are termed. Animals that feed on primary consumers——are secondary consumers. Each of these constitutes a.The sequence of consumption—from plant to herbivore, to carnivore—forms a. Real systems are much more complex than this—organisms will generally feed on more than one form of food, and may feed at more than one trophic level. Carnivores may capture some prey which is part of a plant-based trophic system and others that are part of a detritus-based trophic system (a bird that feeds both on herbivorous grasshoppers and earthworms, which consume detritus). Real systems, with all these complexities, form rather than food chains.

The food chain usually consists of five levels of consumption which are producers, primary consumers, secondary consumers, tertiary consumers, and decomposers. Decomposition. See also:The carbon and nutrients in are broken down by a group of processes known as. This releases nutrients that can then be re-used for plant and microbial production and returns carbon dioxide to the atmosphere (or water) where it can be used for.

In the absence of decomposition, the dead organic matter would accumulate in an ecosystem, and nutrients and atmospheric carbon dioxide would be depleted. Approximately 90% of terrestrial net primary production goes directly from plant to decomposer.Decomposition processes can be separated into three categories—, fragmentation and chemical alteration of dead material.

As water moves through dead organic matter, it dissolves and carries with it the water-soluble components. These are then taken up by organisms in the soil, react with mineral soil, or are transported beyond the confines of the ecosystem (and are considered lost to it). Newly shed leaves and newly dead animals have high concentrations of water-soluble components and include, and mineral nutrients. Leaching is more important in wet environments and much less important in dry ones.Fragmentation processes break organic material into smaller pieces, exposing new surfaces for colonization by microbes. Freshly shed may be inaccessible due to an outer layer of or, and are protected by a. Newly dead animals may be covered by an. Fragmentation processes, which break through these protective layers, accelerate the rate of microbial decomposition.

Animals fragment detritus as they hunt for food, as does passage through the gut. And cycles of wetting and drying also fragment dead material.The chemical alteration of the dead organic matter is primarily achieved through bacterial and fungal action. Fungal produces enzymes that can break through the tough outer structures surrounding dead plant material. They also produce enzymes which break down, which allows them access to both cell contents and the nitrogen in the lignin. Fungi can transfer carbon and nitrogen through their hyphal networks and thus, unlike bacteria, are not dependent solely on locally available resources.Decomposition rates vary among ecosystems. The rate of decomposition is governed by three sets of factors—the physical environment (temperature, moisture, and soil properties), the quantity and quality of the dead material available to decomposers, and the nature of the microbial community itself. Temperature controls the rate of microbial respiration; the higher the temperature, the faster the microbial decomposition occurs.

It also affects soil moisture, which slows microbial growth and reduces leaching. Freeze-thaw cycles also affect decomposition—freezing temperatures kill soil microorganisms, which allows leaching to play a more important role in moving nutrients around.

This can be especially important as the soil thaws in the spring, creating a pulse of nutrients which become available.Decomposition rates are low under very wet or very dry conditions. Decomposition rates are highest in wet, moist conditions with adequate levels of oxygen. Wet soils tend to become deficient in oxygen (this is especially true in ), which slows microbial growth. In dry soils, decomposition slows as well, but bacteria continue to grow (albeit at a slower rate) even after soils become too dry to support plant growth. Biological nitrogen cyclingEcosystems continually exchange energy and carbon with the wider. Mineral nutrients, on the other hand, are mostly cycled back and forth between plants, animals, microbes and the soil. Most nitrogen enters ecosystems through biological, is deposited through precipitation, dust, gases or is applied as.Since most are nitrogen-limited, is an important control on ecosystem production.Until modern times, nitrogen fixation was the major source of nitrogen for ecosystems.

Nitrogen-fixing bacteria either live with plants or live freely in the soil. The energetic cost is high for plants that support nitrogen-fixing symbionts—as much as 25% of gross primary production when measured in controlled conditions. Many members of the plant family support nitrogen-fixing symbionts. Some are also capable of nitrogen fixation.

These are, which carry out photosynthesis. Like other nitrogen-fixing bacteria, they can either be free-living or have symbiotic relationships with plants. Other sources of nitrogen include produced through the combustion of, gas which evaporates from agricultural fields which have had fertilizers applied to them, and dust. Anthropogenic nitrogen inputs account for about 80% of all nitrogen fluxes in ecosystems.When plant tissues are shed or are eaten, the nitrogen in those tissues becomes available to animals and microbes. Microbial decomposition releases nitrogen compounds from dead organic matter in the soil, where plants, fungi, and bacteria compete for it. Some soil bacteria use organic nitrogen-containing compounds as a source of carbon, and release ions into the soil.

This process is known as. Others convert ammonium to and ions, a process known as. And are also produced during nitrification. Under nitrogen-rich and oxygen-poor conditions, nitrates and nitrites are converted to, a process known as.Other important nutrients include,. Phosphorus enters ecosystems through. As ecosystems age this supply diminishes, making phosphorus-limitation more common in older landscapes (especially in the tropics). Calcium and sulfur are also produced by weathering, but acid deposition is an important source of sulfur in many ecosystems.

Although magnesium and manganese are produced by weathering, exchanges between soil organic matter and living cells account for a significant portion of ecosystem fluxes. Potassium is primarily cycled between living cells and soil organic matter.

Function and biodiversity. Spiny forest at Ifaty, featuring various (baobab) species, (Madagascar ocotillo) and other vegetation.plays an important role in ecosystem functioning. The reason for this is that ecosystem processes are driven by the number of species in an ecosystem, the exact nature of each individual species, and the relative abundance organisms within these species.

Ecosystem processes are broad generalizations that actually take place through the actions of individual organisms. The nature of the organisms—the species, and trophic levels to which they belong—dictates the sorts of actions these individuals are capable of carrying out and the relative efficiency with which they do so. Ecological theory suggests that in order to coexist, species must have some level of —they must be different from one another in some fundamental way, otherwise one species would the other. Despite this, the cumulative effect of additional species in an ecosystem is not linear—additional species may enhance nitrogen retention, for example, but beyond some level of species richness, additional species may have little additive effect.The addition (or loss) of species that are ecologically similar to those already present in an ecosystem tends to only have a small effect on ecosystem function.

Ecologically distinct species, on the other hand, have a much larger effect. Similarly, dominant species have a large effect on ecosystem function, while rare species tend to have a small effect.

Tend to have an effect on ecosystem function that is disproportionate to their abundance in an ecosystem. Similarly, an is any that creates, significantly modifies, maintains or destroys a. DynamicsEcosystems are dynamic entities. They are subject to periodic disturbances and are in the process of recovering from some past disturbance.

When a occurs, an ecosystem responds by moving away from its initial state. The tendency of an ecosystem to remain close to its equilibrium state, despite that disturbance, is termed its. On the other hand, the speed with which it returns to its initial state after disturbance is called it's. Time plays a role in the development of soil from bare rock and the.From one year to another, ecosystems experience variation in their biotic and abiotic environments. A drought, a colder than usual winter, and a pest outbreak all are short-term variability in environmental conditions. Animal populations vary from year to year, building up during resource-rich periods and crashing as they overshoot their food supply.

These changes play out in changes in rates, and other ecosystem processes. Longer-term changes also shape ecosystem processes—the forests of eastern North America still show legacies of cultivation which ceased 200 years ago, while production in eastern lakes is controlled by organic matter which accumulated during the.also plays an important role in ecological processes. And coauthors define disturbance as 'a relatively discrete event in time and space that alters the structure of populations, communities, and ecosystems and causes changes in resources availability or the physical environment'. This can range from tree falls and insect outbreaks to hurricanes and wildfires to volcanic eruptions. Such disturbances can cause large changes in plant, animal and microbe populations, as well as soil organic matter content. Disturbance is followed by, a 'directional change in ecosystem structure and functioning resulting from biotically driven changes in resources supply.' The frequency and severity of disturbance determine the way it affects ecosystem function.

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A major disturbance like a volcanic eruption or advance and retreat leave behind soils that lack plants, animals or organic matter. Ecosystems that experience such disturbances undergo.

A less severe disturbance like forest fires, hurricanes or cultivation result in and a faster recovery. More severe disturbance and more frequent disturbance result in longer recovery times. A is an ecosystem on the ocean floor.

(The scale bar is 1 m.)Ecosystem ecology studies the processes and dynamics of ecosystems, and the way the flow of matter and energy through them structures natural systems. The study of ecosystems can cover 10, from the surface layers of rocks to the surface of the planet.There is no single definition of what constitutes an ecosystem. German ecologist Ernst-Detlef Schulze and coauthors defined an ecosystem as an area which is 'uniform regarding the biological turnover, and contains all the fluxes above and below the ground area under consideration.' They explicitly reject ' use of entire as 'too wide a demarcation' to be a single ecosystem, given the level of heterogeneity within such an area. Other authors have suggested that an ecosystem can encompass a much larger area, even the whole planet. Schulze and coauthors also rejected the idea that a single rotting log could be studied as an ecosystem because the size of the flows between the log and its surroundings are too large, relative to the proportion cycles within the log.

Philosopher of science Mark Sagoff considers the failure to define 'the kind of object it studies' to be an obstacle to the development of theory in.Ecosystems can be studied through a variety of approaches—theoretical studies, studies monitoring specific ecosystems over long periods of time, those that look at differences between ecosystems to elucidate how they work and direct manipulative experimentation. Studies can be carried out at a variety of scales, ranging from whole-ecosystem studies to studying or (simplified representations of ecosystems).

American ecologist has argued that microcosm experiments can be 'irrelevant and diversionary' if they are not carried out in conjunction with field studies done at the ecosystem scale. Microcosm experiments often fail to accurately predict ecosystem-level dynamics.The started in 1963 to study the. It was the first successful attempt to study an entire as an ecosystem.

The study used stream as a means of monitoring ecosystem properties, and developed a detailed of the ecosystem. At the site led to the discovery of in North America in 1972. Researchers documented the depletion of soil (especially calcium) over the next several decades. Human activitiesHuman activities are important in almost all ecosystems.

Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate. Ecosystem goods and services. See also: andEcosystems provide a variety of goods and services upon which people depend. Ecosystem goods include the 'tangible, material products' of ecosystem processes such as food, construction material, medicinal plants. They also include less tangible items like and recreation, and genes from wild plants and animals that can be used to improve domestic species., on the other hand, are generally 'improvements in the condition or location of things of value'. These include things like the maintenance of hydrological cycles, cleaning air and water, the maintenance of oxygen in the atmosphere, crop and even things like beauty, inspiration and opportunities for research.

While material from the ecosystem had traditionally been recognized as being the basis for things of economic value, ecosystem services tend to be taken for granted. Ecosystem management. See also:, andWhen is applied to whole ecosystems, rather than single species, it is termed. Although definitions of ecosystem management abound, there is a common set of principles which underlie these definitions. A fundamental principle is the long-term of the production of goods and services by the ecosystem; 'intergenerational sustainability is a precondition for management, not an afterthought'.While ecosystem management can be used as part of a plan for conservation, it can also be used in intensively managed ecosystems (see, for example, and ).Threats caused by humans.

See also:As human population and per capita consumption grow, so do the resource demands imposed on ecosystems and the effects of the human. Natural resources are vulnerable and limited. The environmental impacts of actions are becoming more apparent. Problems for all ecosystems include:,. For further threats include,. For threats include also unsustainable exploitation of marine resources (for example of certain species), pollution, the warming of oceans, and building on coastal areas.Society is increasingly becoming aware that are not only limited but also that they are threatened by human activities. The need to better consider long-term and its role in enabling human habitation and economic activity is urgent.

To help inform decision-makers, many ecosystem services are being assigned economic values, often based on the cost of replacement with anthropogenic alternatives. The ongoing challenge of prescribing economic value to nature, for example through, is prompting transdisciplinary shifts in how we recognize and manage the environment, business opportunities, and our future as a species. See also.

Left: ecosystems are highly marine systems., right: on the in.An ecosystem is a of living organisms in conjunction with the of their environment, interacting as a. These and are linked together through nutrient cycles and energy flows. Energy enters the system through and is incorporated into plant tissue. By feeding on plants and on one-another, animals play an important role in the movement of and through the system.

They also influence the quantity of plant and present. By breaking down dead, release carbon back to the atmosphere and facilitate by converting nutrients stored in dead biomass back to a form that can be readily used by plants and other microbes.Ecosystems are controlled by external and internal. External factors such as, which forms the soil and, control the overall structure of an ecosystem but are not themselves influenced by the ecosystem. Unlike external factors, internal factors are controlled, for example, decomposition, root competition, shading, disturbance, succession, and the types of species present.Ecosystems are entities—they are subject to periodic disturbances and are in the process of recovering from some past disturbance. Ecosystems in similar environments that are located in different parts of the world can end up doing things very differently simply because they have different pools of species present. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to.Resource inputs are generally controlled by external processes like climate and parent material.

Resource availability within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Although humans operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.affects ecosystem functioning, as do the processes of.

Ecosystems provide a variety of upon which people depend. Contents.HistoryThe term ecosystem was first used in 1935 in a publication by British ecologist. Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment. He later refined the term, describing it as 'The whole system.

Including not only the organism-complex, but also the whole complex of physical factors forming what we call the environment'. Tansley regarded ecosystems not simply as natural units, but as 'mental isolates'. Tansley later defined the spatial extent of ecosystems using the term., a who was a contemporary of Tansley's, combined 's ideas about ecology with those of Russian geochemist. As a result, he suggested that mineral nutrient availability in a lake limited. This would, in turn, limit the abundance of animals that feed on algae. Took these ideas further to suggest that the flow of energy through a lake was the primary driver of the ecosystem.

Hutchinson's students, brothers and, further developed a 'systems approach' to the study of ecosystems. This allowed them to study the flow of energy and material through ecological systems.

Biomes of the worldEcosystems are controlled both by external and internal factors. External factors, also called state factors, control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. The most important of these is. Climate determines the in which the ecosystem is embedded. Rainfall patterns and seasonal temperatures influence photosynthesis and thereby determine the amount of water and energy available to the ecosystem.determines the nature of the soil in an ecosystem, and influences the supply of mineral nutrients. Also controls ecosystem processes by affecting things like, soil development and the movement of water through a system. For example, ecosystems can be quite different if situated in a small depression on the landscape, versus one present on an adjacent steep hillside.Other external factors that play an important role in ecosystem functioning include time and potential.

Similarly, the set of organisms that can potentially be present in an area can also significantly affect ecosystems. Ecosystems in similar environments that are located in different parts of the world can end up doing things very differently simply because they have different pools of species present. The can cause substantial shifts in ecosystem function.Unlike external factors, internal factors in ecosystems not only control ecosystem processes but are also controlled by them. Consequently, they are often subject to.

While the inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other factors like disturbance, succession or the types of species present are also internal factors.Primary production. Main article:Primary production is the production of from inorganic carbon sources. This mainly occurs through.

The energy incorporated through this process supports life on earth, while the carbon makes up much of the organic matter in living and dead biomass,. It also drives the, which influences global via the.Through the process of photosynthesis, plants capture energy from light and use it to combine and water to produce. The photosynthesis carried out by all the plants in an ecosystem is called the gross primary production (GPP). About half of the GPP is consumed in plant respiration. The remainder, that portion of GPP that is not used up by respiration, is known as the (NPP). Total photosynthesis is limited by a range of environmental factors. These include the amount of light available, the amount of area a plant has to capture light (shading by other plants is a major limitation of photosynthesis), rate at which carbon dioxide can be supplied to the to support photosynthesis, the availability of water, and the availability of suitable temperatures for carrying out.

See also: andand enter ecosystems through, are incorporated into living tissue, transferred to other organisms that feed on the living and dead plant matter, and eventually released through respiration.The carbon and energy incorporated into plant tissues (net primary production) is either consumed by animals while the plant is alive, or it remains uneaten when the plant tissue dies and becomes. In, roughly 90% of the net primary production ends up being broken down. The remainder is either consumed by animals while still alive and enters the plant-based trophic system, or it is consumed after it has died, and enters the detritus-based trophic system. In, the proportion of plant biomass that gets consumed by is much higher.In trophic systems photosynthetic organisms are the primary producers. The organisms that consume their tissues are called primary consumers or —. Organisms which feed on ( and ) are termed. Animals that feed on primary consumers——are secondary consumers.

Each of these constitutes a.The sequence of consumption—from plant to herbivore, to carnivore—forms a. Real systems are much more complex than this—organisms will generally feed on more than one form of food, and may feed at more than one trophic level. Carnivores may capture some prey which is part of a plant-based trophic system and others that are part of a detritus-based trophic system (a bird that feeds both on herbivorous grasshoppers and earthworms, which consume detritus). Real systems, with all these complexities, form rather than food chains.

The food chain usually consists of five levels of consumption which are producers, primary consumers, secondary consumers, tertiary consumers, and decomposers. Decomposition. See also:The carbon and nutrients in are broken down by a group of processes known as. This releases nutrients that can then be re-used for plant and microbial production and returns carbon dioxide to the atmosphere (or water) where it can be used for. In the absence of decomposition, the dead organic matter would accumulate in an ecosystem, and nutrients and atmospheric carbon dioxide would be depleted. Approximately 90% of terrestrial net primary production goes directly from plant to decomposer.Decomposition processes can be separated into three categories—, fragmentation and chemical alteration of dead material.

As water moves through dead organic matter, it dissolves and carries with it the water-soluble components. These are then taken up by organisms in the soil, react with mineral soil, or are transported beyond the confines of the ecosystem (and are considered lost to it). Newly shed leaves and newly dead animals have high concentrations of water-soluble components and include, and mineral nutrients. Leaching is more important in wet environments and much less important in dry ones.Fragmentation processes break organic material into smaller pieces, exposing new surfaces for colonization by microbes. Freshly shed may be inaccessible due to an outer layer of or, and are protected by a. Newly dead animals may be covered by an.

Fragmentation processes, which break through these protective layers, accelerate the rate of microbial decomposition. Animals fragment detritus as they hunt for food, as does passage through the gut. And cycles of wetting and drying also fragment dead material.The chemical alteration of the dead organic matter is primarily achieved through bacterial and fungal action. Fungal produces enzymes that can break through the tough outer structures surrounding dead plant material. They also produce enzymes which break down, which allows them access to both cell contents and the nitrogen in the lignin. Fungi can transfer carbon and nitrogen through their hyphal networks and thus, unlike bacteria, are not dependent solely on locally available resources.Decomposition rates vary among ecosystems. The rate of decomposition is governed by three sets of factors—the physical environment (temperature, moisture, and soil properties), the quantity and quality of the dead material available to decomposers, and the nature of the microbial community itself.

Temperature controls the rate of microbial respiration; the higher the temperature, the faster the microbial decomposition occurs. It also affects soil moisture, which slows microbial growth and reduces leaching. Freeze-thaw cycles also affect decomposition—freezing temperatures kill soil microorganisms, which allows leaching to play a more important role in moving nutrients around. This can be especially important as the soil thaws in the spring, creating a pulse of nutrients which become available.Decomposition rates are low under very wet or very dry conditions. Decomposition rates are highest in wet, moist conditions with adequate levels of oxygen.

Wet soils tend to become deficient in oxygen (this is especially true in ), which slows microbial growth. In dry soils, decomposition slows as well, but bacteria continue to grow (albeit at a slower rate) even after soils become too dry to support plant growth. Biological nitrogen cyclingEcosystems continually exchange energy and carbon with the wider. Mineral nutrients, on the other hand, are mostly cycled back and forth between plants, animals, microbes and the soil. Most nitrogen enters ecosystems through biological, is deposited through precipitation, dust, gases or is applied as.Since most are nitrogen-limited, is an important control on ecosystem production.Until modern times, nitrogen fixation was the major source of nitrogen for ecosystems. Nitrogen-fixing bacteria either live with plants or live freely in the soil. The energetic cost is high for plants that support nitrogen-fixing symbionts—as much as 25% of gross primary production when measured in controlled conditions.

Many members of the plant family support nitrogen-fixing symbionts. Some are also capable of nitrogen fixation. These are, which carry out photosynthesis. Like other nitrogen-fixing bacteria, they can either be free-living or have symbiotic relationships with plants. Other sources of nitrogen include produced through the combustion of, gas which evaporates from agricultural fields which have had fertilizers applied to them, and dust. Anthropogenic nitrogen inputs account for about 80% of all nitrogen fluxes in ecosystems.When plant tissues are shed or are eaten, the nitrogen in those tissues becomes available to animals and microbes. Microbial decomposition releases nitrogen compounds from dead organic matter in the soil, where plants, fungi, and bacteria compete for it.

Some soil bacteria use organic nitrogen-containing compounds as a source of carbon, and release ions into the soil. This process is known as. Others convert ammonium to and ions, a process known as. And are also produced during nitrification. Under nitrogen-rich and oxygen-poor conditions, nitrates and nitrites are converted to, a process known as.Other important nutrients include,. Phosphorus enters ecosystems through. As ecosystems age this supply diminishes, making phosphorus-limitation more common in older landscapes (especially in the tropics).

Calcium and sulfur are also produced by weathering, but acid deposition is an important source of sulfur in many ecosystems. Although magnesium and manganese are produced by weathering, exchanges between soil organic matter and living cells account for a significant portion of ecosystem fluxes. Potassium is primarily cycled between living cells and soil organic matter.

Function and biodiversity. Spiny forest at Ifaty, featuring various (baobab) species, (Madagascar ocotillo) and other vegetation.plays an important role in ecosystem functioning.

The reason for this is that ecosystem processes are driven by the number of species in an ecosystem, the exact nature of each individual species, and the relative abundance organisms within these species. Ecosystem processes are broad generalizations that actually take place through the actions of individual organisms. The nature of the organisms—the species, and trophic levels to which they belong—dictates the sorts of actions these individuals are capable of carrying out and the relative efficiency with which they do so. Ecological theory suggests that in order to coexist, species must have some level of —they must be different from one another in some fundamental way, otherwise one species would the other. Despite this, the cumulative effect of additional species in an ecosystem is not linear—additional species may enhance nitrogen retention, for example, but beyond some level of species richness, additional species may have little additive effect.The addition (or loss) of species that are ecologically similar to those already present in an ecosystem tends to only have a small effect on ecosystem function. Ecologically distinct species, on the other hand, have a much larger effect.

Similarly, dominant species have a large effect on ecosystem function, while rare species tend to have a small effect. Tend to have an effect on ecosystem function that is disproportionate to their abundance in an ecosystem. Similarly, an is any that creates, significantly modifies, maintains or destroys a.

DynamicsEcosystems are dynamic entities. They are subject to periodic disturbances and are in the process of recovering from some past disturbance. When a occurs, an ecosystem responds by moving away from its initial state. The tendency of an ecosystem to remain close to its equilibrium state, despite that disturbance, is termed its. On the other hand, the speed with which it returns to its initial state after disturbance is called it's. Time plays a role in the development of soil from bare rock and the.From one year to another, ecosystems experience variation in their biotic and abiotic environments. A drought, a colder than usual winter, and a pest outbreak all are short-term variability in environmental conditions.

Animal populations vary from year to year, building up during resource-rich periods and crashing as they overshoot their food supply. These changes play out in changes in rates, and other ecosystem processes. Longer-term changes also shape ecosystem processes—the forests of eastern North America still show legacies of cultivation which ceased 200 years ago, while production in eastern lakes is controlled by organic matter which accumulated during the.also plays an important role in ecological processes. And coauthors define disturbance as 'a relatively discrete event in time and space that alters the structure of populations, communities, and ecosystems and causes changes in resources availability or the physical environment'. This can range from tree falls and insect outbreaks to hurricanes and wildfires to volcanic eruptions.

Such disturbances can cause large changes in plant, animal and microbe populations, as well as soil organic matter content. Disturbance is followed by, a 'directional change in ecosystem structure and functioning resulting from biotically driven changes in resources supply.' The frequency and severity of disturbance determine the way it affects ecosystem function. A major disturbance like a volcanic eruption or advance and retreat leave behind soils that lack plants, animals or organic matter. Ecosystems that experience such disturbances undergo. A less severe disturbance like forest fires, hurricanes or cultivation result in and a faster recovery. More severe disturbance and more frequent disturbance result in longer recovery times.

A is an ecosystem on the ocean floor. (The scale bar is 1 m.)Ecosystem ecology studies the processes and dynamics of ecosystems, and the way the flow of matter and energy through them structures natural systems.

The study of ecosystems can cover 10, from the surface layers of rocks to the surface of the planet.There is no single definition of what constitutes an ecosystem. German ecologist Ernst-Detlef Schulze and coauthors defined an ecosystem as an area which is 'uniform regarding the biological turnover, and contains all the fluxes above and below the ground area under consideration.' They explicitly reject ' use of entire as 'too wide a demarcation' to be a single ecosystem, given the level of heterogeneity within such an area. Other authors have suggested that an ecosystem can encompass a much larger area, even the whole planet.

Schulze and coauthors also rejected the idea that a single rotting log could be studied as an ecosystem because the size of the flows between the log and its surroundings are too large, relative to the proportion cycles within the log. Philosopher of science Mark Sagoff considers the failure to define 'the kind of object it studies' to be an obstacle to the development of theory in.Ecosystems can be studied through a variety of approaches—theoretical studies, studies monitoring specific ecosystems over long periods of time, those that look at differences between ecosystems to elucidate how they work and direct manipulative experimentation.

Studies can be carried out at a variety of scales, ranging from whole-ecosystem studies to studying or (simplified representations of ecosystems). American ecologist has argued that microcosm experiments can be 'irrelevant and diversionary' if they are not carried out in conjunction with field studies done at the ecosystem scale. Microcosm experiments often fail to accurately predict ecosystem-level dynamics.The started in 1963 to study the.

It was the first successful attempt to study an entire as an ecosystem. The study used stream as a means of monitoring ecosystem properties, and developed a detailed of the ecosystem. At the site led to the discovery of in North America in 1972. Researchers documented the depletion of soil (especially calcium) over the next several decades.

Human activitiesHuman activities are important in almost all ecosystems. Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate. Ecosystem goods and services. See also: andEcosystems provide a variety of goods and services upon which people depend. Ecosystem goods include the 'tangible, material products' of ecosystem processes such as food, construction material, medicinal plants. They also include less tangible items like and recreation, and genes from wild plants and animals that can be used to improve domestic species., on the other hand, are generally 'improvements in the condition or location of things of value'. These include things like the maintenance of hydrological cycles, cleaning air and water, the maintenance of oxygen in the atmosphere, crop and even things like beauty, inspiration and opportunities for research.

While material from the ecosystem had traditionally been recognized as being the basis for things of economic value, ecosystem services tend to be taken for granted. Ecosystem management. See also:, andWhen is applied to whole ecosystems, rather than single species, it is termed.

Although definitions of ecosystem management abound, there is a common set of principles which underlie these definitions. A fundamental principle is the long-term of the production of goods and services by the ecosystem; 'intergenerational sustainability is a precondition for management, not an afterthought'.While ecosystem management can be used as part of a plan for conservation, it can also be used in intensively managed ecosystems (see, for example, and ).Threats caused by humans. See also:As human population and per capita consumption grow, so do the resource demands imposed on ecosystems and the effects of the human.

Natural resources are vulnerable and limited. The environmental impacts of actions are becoming more apparent.

Problems for all ecosystems include:,. For further threats include,. For threats include also unsustainable exploitation of marine resources (for example of certain species), pollution, the warming of oceans, and building on coastal areas.Society is increasingly becoming aware that are not only limited but also that they are threatened by human activities. The need to better consider long-term and its role in enabling human habitation and economic activity is urgent. To help inform decision-makers, many ecosystem services are being assigned economic values, often based on the cost of replacement with anthropogenic alternatives. The ongoing challenge of prescribing economic value to nature, for example through, is prompting transdisciplinary shifts in how we recognize and manage the environment, business opportunities, and our future as a species. See also.