Ecosystem ecology

Last updated
Figure 1. A riparian forest in the White Mountains, New Hampshire (USA). Ecoecolfigure1.jpg
Figure 1. A riparian forest in the White Mountains, New Hampshire (USA).

Ecosystem ecology is the integrated study of living (biotic) and non-living (abiotic) components of ecosystems and their interactions within an ecosystem framework. This science examines how ecosystems work and relates this to their components such as chemicals, bedrock, soil, plants, and animals.

Contents

Ecosystem ecology examines physical and biological structures and examines how these ecosystem characteristics interact with each other. Ultimately, this helps us understand how to maintain high quality water and economically viable commodity production. A major focus of ecosystem ecology is on functional processes, ecological mechanisms that maintain the structure and services produced by ecosystems. These include primary productivity (production of biomass), decomposition, and trophic interactions.

Studies of ecosystem function have greatly improved human understanding of sustainable production of forage, fiber, fuel, and provision of water. Functional processes are mediated by regional-to-local level climate, disturbance, and management. Thus ecosystem ecology provides a powerful framework for identifying ecological mechanisms that interact with global environmental problems, especially global warming and degradation of surface water.

This example demonstrates several important aspects of ecosystems:

  1. Ecosystem boundaries are often nebulous and may fluctuate in time
  2. Organisms within ecosystems are dependent on ecosystem level biological and physical processes
  3. Adjacent ecosystems closely interact and often are interdependent for maintenance of community structure and functional processes that maintain productivity and biodiversity

These characteristics also introduce practical problems into natural resource management. Who will manage which ecosystem? Will timber cutting in the forest degrade recreational fishing in the stream? These questions are difficult for land managers to address while the boundary between ecosystems remains unclear; even though decisions in one ecosystem will affect the other. We need better understanding of the interactions and interdependencies of these ecosystems and the processes that maintain them before we can begin to address these questions.

Ecosystem ecology is an inherently interdisciplinary field of study. An individual ecosystem is composed of populations of organisms, interacting within communities, and contributing to the cycling of nutrients and the flow of energy. The ecosystem is the principal unit of study in ecosystem ecology.

Population, community, and physiological ecology provide many of the underlying biological mechanisms influencing ecosystems and the processes they maintain. Flowing of energy and cycling of matter at the ecosystem level are often examined in ecosystem ecology, but, as a whole, this science is defined more by subject matter than by scale. Ecosystem ecology approaches organisms and abiotic pools of energy and nutrients as an integrated system which distinguishes it from associated sciences such as biogeochemistry. [1]

Biogeochemistry and hydrology focus on several fundamental ecosystem processes such as biologically mediated chemical cycling of nutrients and physical-biological cycling of water. Ecosystem ecology forms the mechanistic basis for regional or global processes encompassed by landscape-to-regional hydrology, global biogeochemistry, and earth system science. [1]

History

Ecosystem ecology is philosophically and historically rooted in terrestrial ecology. The ecosystem concept has evolved rapidly during the last 100 years with important ideas developed by Frederic Clements, a botanist who argued for specific definitions of ecosystems and that physiological processes were responsible for their development and persistence. [2] Although most of Clements ecosystem definitions have been greatly revised, initially by Henry Gleason and Arthur Tansley, and later by contemporary ecologists, the idea that physiological processes are fundamental to ecosystem structure and function remains central to ecology.

Figure 3. Energy and matter flows through an ecosystem, adapted from the Silver Springs model. H are herbivores, C are carnivores, TC are top carnivores, and D are decomposers. Squares represent biotic pools and ovals are fluxes or energy or nutrients from the system. Silver Spring Model.jpg
Figure 3. Energy and matter flows through an ecosystem, adapted from the Silver Springs model. H are herbivores, C are carnivores, TC are top carnivores, and D are decomposers. Squares represent biotic pools and ovals are fluxes or energy or nutrients from the system.

Later work by Eugene Odum and Howard T. Odum quantified flows of energy and matter at the ecosystem level, thus documenting the general ideas proposed by Clements and his contemporary Charles Elton.

In this model, energy flows through the whole system were dependent on biotic and abiotic interactions of each individual component (species, inorganic pools of nutrients, etc.). Later work demonstrated that these interactions and flows applied to nutrient cycles, changed over the course of succession, and held powerful controls over ecosystem productivity. [4] [5] Transfers of energy and nutrients are innate to ecological systems regardless of whether they are aquatic or terrestrial. Thus, ecosystem ecology has emerged from important biological studies of plants, animals, terrestrial, aquatic, and marine ecosystems.

Ecosystem services

Ecosystem services are ecologically mediated functional processes essential to sustaining healthy human societies. [6] Water provision and filtration, production of biomass in forestry, agriculture, and fisheries, and removal of greenhouse gases such as carbon dioxide (CO2) from the atmosphere are examples of ecosystem services essential to public health and economic opportunity. Nutrient cycling is a process fundamental to agricultural and forest production.

However, like most ecosystem processes, nutrient cycling is not an ecosystem characteristic which can be “dialed” to the most desirable level. Maximizing production in degraded systems is an overly simplistic solution to the complex problems of hunger and economic security. For instance, intensive fertilizer use in the midwestern United States has resulted in degraded fisheries in the Gulf of Mexico. [7] Regrettably, a “Green Revolution” of intensive chemical fertilization has been recommended for agriculture in developed and developing countries. [8] [9] These strategies risk alteration of ecosystem processes that may be difficult to restore, especially when applied at broad scales without adequate assessment of impacts. Ecosystem processes may take many years to recover from significant disturbance. [5]

For instance, large-scale forest clearance in the northeastern United States during the 18th and 19th centuries has altered soil texture, dominant vegetation, and nutrient cycling in ways that impact forest productivity in the present day. [10] [11] An appreciation of the importance of ecosystem function in maintenance of productivity, whether in agriculture or forestry, is needed in conjunction with plans for restoration of essential processes. Improved knowledge of ecosystem function will help to achieve long-term sustainability and stability in the poorest parts of the world.

Operation

Biomass productivity is one of the most apparent and economically important ecosystem functions. Biomass accumulation begins at the cellular level via photosynthesis. Photosynthesis requires water and consequently global patterns of annual biomass production are correlated with annual precipitation. [12] Amounts of productivity are also dependent on the overall capacity of plants to capture sunlight which is directly correlated with plant leaf area and N content.

Net primary productivity (NPP) is the primary measure of biomass accumulation within an ecosystem. Net primary productivity can be calculated by a simple formula where the total amount of productivity is adjusted for total productivity losses through maintenance of biological processes:

NPP = GPP – Rproducer
Figure 4. Seasonal and annual changes in ambient carbon dioxide (CO2) concentration at Mauna Loa Hawaii (Atmosphere) and above the canopy of a deciduous forest in Massachusetts (Forest). Data show clear seasonal trends associated with periods of high and low NPP and an overall annual increase of atmospheric CO2. Data approximates of those reported by Keeling and Whorf and Barford. Ecoecolfigure4.jpg
Figure 4. Seasonal and annual changes in ambient carbon dioxide (CO2) concentration at Mauna Loa Hawaii (Atmosphere) and above the canopy of a deciduous forest in Massachusetts (Forest). Data show clear seasonal trends associated with periods of high and low NPP and an overall annual increase of atmospheric CO2. Data approximates of those reported by Keeling and Whorf and Barford.

Where GPP is gross primary productivity and Rproducer is photosynthate (Carbon) lost via cellular respiration.

NPP is difficult to measure but a new technique known as eddy co-variance has shed light on how natural ecosystems influence the atmosphere. Figure 4 shows seasonal and annual changes in CO2 concentration measured at Mauna Loa, Hawaii from 1987 to 1990. CO2 concentration steadily increased, but within-year variation has been greater than the annual increase since measurements began in 1957.

These variations were thought to be due to seasonal uptake of CO2 during summer months. A newly developed technique for assessing ecosystem NPP has confirmed seasonal variation are driven by seasonal changes in CO2 uptake by vegetation. [15] [14] This has led many scientists and policy makers to speculate that ecosystems can be managed to ameliorate problems with global warming. This type of management may include reforesting or altering forest harvest schedules for many parts of the world.

Decomposition and nutrient cycling

Decomposition and nutrient cycling are fundamental to ecosystem biomass production. Most natural ecosystems are nitrogen (N) limited and biomass production is closely correlated with N turnover. [16] [17] Typically external input of nutrients is very low and efficient recycling of nutrients maintains productivity. [5] Decomposition of plant litter accounts for the majority of nutrients recycled through ecosystems (Figure 3). Rates of plant litter decomposition are highly dependent on litter quality; high concentration of phenolic compounds, especially lignin, in plant litter has a retarding effect on litter decomposition. [18] [19] More complex C compounds are decomposed more slowly and may take many years to completely breakdown. Decomposition is typically described with exponential decay and has been related to the mineral concentrations, especially manganese, in the leaf litter. [20] [21]

Figure 5. Dynamics of decomposing plant litter (A) described with an exponential model (B) and a combined exponential-linear model (C). Ecoecolfigure5.jpg
Figure 5. Dynamics of decomposing plant litter (A) described with an exponential model (B) and a combined exponential-linear model (C).

Globally, rates of decomposition are mediated by litter quality and climate. [22] Ecosystems dominated by plants with low-lignin concentration often have rapid rates of decomposition and nutrient cycling (Chapin et al. 1982). Simple carbon (C) containing compounds are preferentially metabolized by decomposer microorganisms which results in rapid initial rates of decomposition, see Figure 5A, [23] models that depend on constant rates of decay; so called “k” values, see Figure 5B. [24] In addition to litter quality and climate, the activity of soil fauna is very important [25]

However, these models do not reflect simultaneous linear and non-linear decay processes which likely occur during decomposition. For instance, proteins, sugars and lipids decompose exponentially, but lignin decays at a more linear rate [18] Thus, litter decay is inaccurately predicted by simplistic models. [26]

A simple alternative model presented in Figure 5C shows significantly more rapid decomposition that the standard model of figure 4B. Better understanding of decomposition models is an important research area of ecosystem ecology because this process is closely tied to nutrient supply and the overall capacity of ecosystems to sequester CO2 from the atmosphere.

Trophic dynamics

Trophic dynamics refers to process of energy and nutrient transfer between organisms. Trophic dynamics is an important part of the structure and function of ecosystems. Figure 3 shows energy transferred for an ecosystem at Silver Springs, Florida. Energy gained by primary producers (plants, P) is consumed by herbivores (H), which are consumed by carnivores (C), which are themselves consumed by “top- carnivores”(TC).

One of the most obvious patterns in Figure 3 is that as one moves up to higher trophic levels (i.e. from plants to top-carnivores) the total amount of energy decreases. Plants exert a “bottom-up” control on the energy structure of ecosystems by determining the total amount of energy that enters the system. [27]

However, predators can also influence the structure of lower trophic levels from the top-down. These influences can dramatically shift dominant species in terrestrial and marine systems [28] [29] The interplay and relative strength of top-down vs. bottom-up controls on ecosystem structure and function is an important area of research in the greater field of ecology.

Trophic dynamics can strongly influence rates of decomposition and nutrient cycling in time and in space. For example, herbivory can increase litter decomposition and nutrient cycling via direct changes in litter quality and altered dominant vegetation. [30] Insect herbivory has been shown to increase rates of decomposition and nutrient turnover due to changes in litter quality and increased frass inputs. [1] [31]

However, insect outbreak does not always increase nutrient cycling. Stadler [32] showed that C rich honeydew produced during aphid outbreak can result in increased N immobilization by soil microbes thus slowing down nutrient cycling and potentially limiting biomass production. North atlantic marine ecosystems have been greatly altered by overfishing of cod. Cod stocks crashed in the 1990s which resulted in increases in their prey such as shrimp and snow crab [29] Human intervention in ecosystems has resulted in dramatic changes to ecosystem structure and function. These changes are occurring rapidly and have unknown consequences for economic security and human well-being. [33]

Applications and importance

Lessons from two Central American cities

The biosphere has been greatly altered by the demands of human societies. Ecosystem ecology plays an important role in understanding and adapting to the most pressing current environmental problems. Restoration ecology and ecosystem management are closely associated with ecosystem ecology. Restoring highly degraded resources depends on integration of functional mechanisms of ecosystems. [34]

Without these functions intact, economic value of ecosystems is greatly reduced and potentially dangerous conditions may develop in the field. For example, areas within the mountainous western highlands of Guatemala are more susceptible to catastrophic landslides and crippling seasonal water shortages due to loss of forest resources. In contrast, cities such as Totonicapán that have preserved forests through strong social institutions have greater local economic stability and overall greater human well-being. [35]

This situation is striking considering that these areas are close to each other, the majority of inhabitants are of Mayan descent, and the topography and overall resources are similar. This is a case of two groups of people managing resources in fundamentally different ways. Ecosystem ecology provides the basic science needed to avoid degradation and to restore ecosystem processes that provide for basic human needs.

See also


Related Research Articles

<span class="mw-page-title-main">Ecosystem</span> Community of living organisms together with the nonliving components of their environment

An ecosystem consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and microbes.

This glossary of ecology is a list of definitions of terms and concepts in ecology and related fields. For more specific definitions from other glossaries related to ecology, see Glossary of biology, Glossary of evolutionary biology, and Glossary of environmental science.

<span class="mw-page-title-main">Energy flow (ecology)</span> Flow of energy through food chains in ecological energetics

Energy flow is the flow of energy through living things within an ecosystem. All living organisms can be organized into producers and consumers, and those producers and consumers can further be organized into a food chain. Each of the levels within the food chain is a trophic level. In order to more efficiently show the quantity of organisms at each trophic level, these food chains are then organized into trophic pyramids. The arrows in the food chain show that the energy flow is unidirectional, with the head of an arrow indicating the direction of energy flow; energy is lost as heat at each step along the way.

<span class="mw-page-title-main">Decomposer</span> Organism that breaks down dead or decaying organisms

Decomposers are organisms that break down dead or decaying organisms; they carry out decomposition, a process possible by only certain kingdoms, such as fungi. Like herbivores and predators, decomposers are heterotrophic, meaning that they use organic substrates to get their energy, carbon and nutrients for growth and development. While the terms decomposer and detritivore are often interchangeably used, detritivores ingest and digest dead matter internally, while decomposers directly absorb nutrients through external chemical and biological processes. Thus, invertebrates such as earthworms, woodlice, and sea cucumbers are technically detritivores, not decomposers, since they are unable to absorb nutrients without ingesting them.

<span class="mw-page-title-main">Detritivore</span> Animal that feeds on decomposing plant and animal parts as well as faeces

Detritivores are heterotrophs that obtain nutrients by consuming detritus. There are many kinds of invertebrates, vertebrates and plants that carry out coprophagy. By doing so, all these detritivores contribute to decomposition and the nutrient cycles. They should be distinguished from other decomposers, such as many species of bacteria, fungi and protists, which are unable to ingest discrete lumps of matter, but instead live by absorbing and metabolizing on a molecular scale. The terms detritivore and decomposer are often used interchangeably, but they describe different organisms. Detritivores are usually arthropods and help in the process of remineralization. Detritivores perform the first stage of remineralization, by fragmenting the dead plant matter, allowing decomposers to perform the second stage of remineralization.

<span class="mw-page-title-main">Coarse woody debris</span>

Coarse woody debris (CWD) or coarse woody habitat (CWH) refers to fallen dead trees and the remains of large branches on the ground in forests and in rivers or wetlands. A dead standing tree – known as a snag – provides many of the same functions as coarse woody debris. The minimum size required for woody debris to be defined as "coarse" varies by author, ranging from 2.5–20 cm (1–8 in) in diameter.

<span class="mw-page-title-main">Soil food web</span>

The soil food web is the community of organisms living all or part of their lives in the soil. It describes a complex living system in the soil and how it interacts with the environment, plants, and animals.

<span class="mw-page-title-main">Soil biology</span>

Soil biology is the study of microbial and faunal activity and ecology in soil. Soil life, soil biota, soil fauna, or edaphon is a collective term that encompasses all organisms that spend a significant portion of their life cycle within a soil profile, or at the soil-litter interface. These organisms include earthworms, nematodes, protozoa, fungi, bacteria, different arthropods, as well as some reptiles, and species of burrowing mammals like gophers, moles and prairie dogs. Soil biology plays a vital role in determining many soil characteristics. The decomposition of organic matter by soil organisms has an immense influence on soil fertility, plant growth, soil structure, and carbon storage. As a relatively new science, much remains unknown about soil biology and its effect on soil ecosystems.

<span class="mw-page-title-main">Microbial loop</span>

The microbial loop describes a trophic pathway where, in aquatic systems, dissolved organic carbon (DOC) is returned to higher trophic levels via its incorporation into bacterial biomass, and then coupled with the classic food chain formed by phytoplankton-zooplankton-nekton. In soil systems, the microbial loop refers to soil carbon. The term microbial loop was coined by Farooq Azam, Tom Fenchel et al. in 1983 to include the role played by bacteria in the carbon and nutrient cycles of the marine environment.

<span class="mw-page-title-main">Human impact on the nitrogen cycle</span>

Human impact on the nitrogen cycle is diverse. Agricultural and industrial nitrogen (N) inputs to the environment currently exceed inputs from natural N fixation. As a consequence of anthropogenic inputs, the global nitrogen cycle (Fig. 1) has been significantly altered over the past century. Global atmospheric nitrous oxide (N2O) mole fractions have increased from a pre-industrial value of ~270 nmol/mol to ~319 nmol/mol in 2005. Human activities account for over one-third of N2O emissions, most of which are due to the agricultural sector. This article is intended to give a brief review of the history of anthropogenic N inputs, and reported impacts of nitrogen inputs on selected terrestrial and aquatic ecosystems.

<span class="mw-page-title-main">Soil respiration</span> Chemical process produced by soil and the organisms within it

Soil respiration refers to the production of carbon dioxide when soil organisms respire. This includes respiration of plant roots, the rhizosphere, microbes and fauna.

Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. SOM provides numerous benefits to the physical and chemical properties of soil and its capacity to provide regulatory ecosystem services. SOM is especially critical for soil functions and quality.

<span class="mw-page-title-main">Forest floor</span> Layer of the forest ecosystem above the soil composed of primarily non-living organic material

The forest floor, also called detritus or duff, is the part of a forest ecosystem that mediates between the living, aboveground portion of the forest and the mineral soil, principally composed of dead and decaying plant matter such as rotting wood and shed leaves. In some countries, like Canada, forest floor refers to L, F and H organic horizons. It hosts a wide variety of decomposers and predators, including invertebrates, fungi, algae, bacteria, and archaea.

<span class="mw-page-title-main">Plant litter</span> Dead plant material that has fallen to the ground

Plant litter is dead plant material that have fallen to the ground. This detritus or dead organic material and its constituent nutrients are added to the top layer of soil, commonly known as the litter layer or O horizon. Litter is an important factor in ecosystem dynamics, as it is indicative of ecological productivity and may be useful in predicting regional nutrient cycling and soil fertility.

FORECAST is a management-oriented, stand-level, forest-growth and ecosystem-dynamics model. The model was designed to accommodate a wide variety of silvicultural and harvesting systems and natural disturbance events in order to compare and contrast their effect on forest productivity, stand dynamics, and a series of biophysical indicators of non-timber values.

<span class="mw-page-title-main">Nutrient cycle</span> Set of processes exchanging nutrients between parts of a system

A nutrient cycle is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyclic. Mineral cycles include the carbon cycle, sulfur cycle, nitrogen cycle, water cycle, phosphorus cycle, oxygen cycle, among others that continually recycle along with other mineral nutrients into productive ecological nutrition.

<span class="mw-page-title-main">Mycorrhizal fungi and soil carbon storage</span>

Soil carbon storage is an important function of terrestrial ecosystems. Soil contains more carbon than plants and the atmosphere combined. Understanding what maintains the soil carbon pool is important to understand the current distribution of carbon on Earth, and how it will respond to environmental change. While much research has been done on how plants, free-living microbial decomposers, and soil minerals affect this pool of carbon, it is recently coming to light that mycorrhizal fungi—symbiotic fungi that associate with roots of almost all living plants—may play an important role in maintaining this pool as well. Measurements of plant carbon allocation to mycorrhizal fungi have been estimated to be 5 to 20% of total plant carbon uptake, and in some ecosystems the biomass of mycorrhizal fungi can be comparable to the biomass of fine roots. Recent research has shown that mycorrhizal fungi hold 50 to 70 percent of the total carbon stored in leaf litter and soil on forested islands in Sweden. Turnover of mycorrhizal biomass into the soil carbon pool is thought to be rapid and has been shown in some ecosystems to be the dominant pathway by which living carbon enters the soil carbon pool.

<span class="mw-page-title-main">Fungal extracellular enzyme activity</span> Enzymes produced by fungi and secreted outside their cells

Extracellular enzymes or exoenzymes are synthesized inside the cell and then secreted outside the cell, where their function is to break down complex macromolecules into smaller units to be taken up by the cell for growth and assimilation. These enzymes degrade complex organic matter such as cellulose and hemicellulose into simple sugars that enzyme-producing organisms use as a source of carbon, energy, and nutrients. Grouped as hydrolases, lyases, oxidoreductases and transferases, these extracellular enzymes control soil enzyme activity through efficient degradation of biopolymers.

A fine root is most commonly defined as a plant root that is two millimeters or less in diameter. Fine roots may function in acquisition of soil resources and/or resource transport, making them functionally most analogous to the leaves and twigs in a plant's shoot system. Fine-root traits are variable between species and responsive to environmental conditions. Consequently, fine roots are studied to characterize the resource acquisition strategies and competitive ability of plant species. Categories of fine roots have been developed based on root diameter, position in a root system's branching hierarchy, and primary function. Fine roots are often associated with symbiotic fungi and play a role in many ecosystem processes like nutrient cycles and soil reinforcement.

The term humus form is not the same as the term humus. Forest humus form describes the various arrangement of organic and mineral horizons at the top of soil profiles. It can be composed entirely of organic horizons, meaning an absence of the mineral horizon. Experts worldwide have developed different types of classifications over time, and humus forms are mainly categorized into mull, mor, and moder orders in the ecosystems of British Columbia. Mull humus form is distinguishable from the other two forms in formation, nutrient cycling, productivity, etc.

References

  1. 1 2 3 Chapman, S.K., Hart, S.C., Cobb, N.S., Whitham, T.G., and Koch, G.W. (2003). "Insect herbivory increases litter quality and decomposition: an extension of the acceleration hypothesis". in: Ecology 84:2867-2876.
  2. ↑ Hagen, J.B. (1992). An Entangled Bank: The origins of ecosystem ecology. Rutgers University Press, New Brunswick, N.J.
  3. ↑ Odum, H.T. (1971). Environment, Power, and Society. Wiley-Interscience New York, N.Y.
  4. ↑ Odum, E.P 1969. "The strategy of ecosystem development". in: Science 164:262-270.
  5. 1 2 3 Likens, G. E., F. H. Bormann, N. M. Johnson, D. W. Fisher and R. S. Pierce. (1970). "Effects of forest cutting and herbicide treatment on nutrient budgets in the Hubbard Brook watershed-ecosystem". in: Ecological Monographs 40:23-47.
  6. ↑ Chapin, F.S. III, B.H., Walker, R.J., Hobbs, D.U., Hooper, J.H., Lawton, O.E., Sala, and D., Tilman. (1997). "Biotic control over the functioning of ecosystems". in: Science 277:500-504.
  7. ↑ Defries, R.S., J.A. Foley, and G.P. Asner. (2004). "Land-use choices: balancing human needs and ecosystem function". in: Frontiers in ecology and environmental science. 2:249-257.
  8. ↑ Chrispeels, M.J. and Sadava, D. (1977). Plants, food, and people. W. H. Freeman and Company, San Francisco.
  9. ↑ Quinones, M.A., N.E. Borlaug, C.R. Dowswell. (1997). "A fertilizer-based green revolution for Africa". In: Replenishing soil fertility in Africa. Soil Science Society of America special publication number 51. Soil Science Society of America, Madison, WI.
  10. ↑ Foster, D. R. (1992). "Land-use history (1730-1990) and vegetation dynamics in central New England, USA". In: Journal of Ecology 80: 753-772.
  11. ↑ Motzkin, G., D. R. Foster, A. Allen, J. Harrod, and R. D. Boone. (1996). "Controlling site to evaluate history: vegetation patterns of a New England sand plain". In: Ecological Monographs 66: 345-365.
  12. ↑ Huxman TE, ea.(2004). "Convergence across biomes to a common rain-use efficiency". Nature. 429: 651-654
  13. ↑ Keeling, C.D. and T.P. Whorf. (2005). "Atmospheric CO2 records from sites in the SIO air sampling network". In: Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.
  14. 1 2 Barford, C. C., ea. (2001). "Factors controlling long and short term sequestration of atmospheric CO2 in a mid-latitude forest". In: Science 294: 1688-1691
  15. ↑ Goulden, M. L., J. W. Munger, S.-M. Fan, B. C. Daube, and S. C. Wofsy, (1996). "Effects of interannual climate variability on the carbon dioxide exchange of a temperate deciduous forest". In: Science 271:1576-1578
  16. ↑ Vitousek, P.M. and Howarth, R.W. (1991). "Nitrogen limitation on land and in the sea: how can it occur?" In: Biogeochemistry 13:87-115.
  17. ↑ Reich, P.B., Grigal, D.F., Aber, J.D., Gower, S.T. (1997). "Nitrogen mineralization and productivity in 50 hardwood and conifer stands on diverse soils". In: Ecology 78:335-347.
  18. 1 2 Melillo, J.M., Aber, J.D., and Muratore, J.F. (1982). "Nitrogen and lignin control of hardwood leaf litter decomposition dynamics". In: Ecology 63:621-626.
  19. ↑ Hättenschwiler S. and P.M. Vitousek (2000). "The role of polyphenols in terrestrial ecosystem nutrient cycling". In: Trends in Ecology and Evolution 15: 238-243
  20. ↑ Davey MP, B Berg, P Rowland, BA Emmett. 2007. Decomposition of oak leaf litter is related to initial litter Mn concentrations. Canadian Journal of Botany. 85(1). 16-24.
  21. ↑ Berg B, Davey MP, Emmett B, Faituri M, Hobbie S, Johansson MB, Liu C, De Marco A, McClaugherty C, Norell L, Rutigliano F, De Santo AV. 2010. Factors influencing limit values for pine needle litter decomposition - a synthesis for boreal and temperate pine forest systems. Biogeochemistry. 100: 57-73
  22. ↑ Meentemeyer, V. 1978 "Macroclimate and lignin control of litter decomposition rates". in: Ecology 59:465-472.
  23. ↑ Aber, J.D., and J.M., Melillo (1982). "Nitrogen immobilization in decaying hardwood leaf litter as a function of initial nitrogen and lignin content". In: Canadian Journal of Botany 60:2263-2269.
  24. ↑ Olson, J.S. (1963). "Energy storage and the balance of producers and decomposers in ecological systems". In: Ecology 44:322-331.
  25. ↑ Castro-Huerta, R.; Falco, L.; Sandler, R.; Coviella, C. (2015). "Differential contribution of soil biota groups to plant litter decomposition as mediated by soil use". PeerJ . 3: e826. doi:10.7717/peerj.826. PMC   4359044 . PMID   25780777.
  26. ↑ Carpenter, S.A. (1981). "Decay of heterogeneous detritus: a general model". In: Journal of theoretical biology 89:539-547.
  27. ↑ Chapin F.S. III, Matson, P.A., and Mooney, H.A. (2003). Principles of terrestrial ecosystem ecology. Springer-Verlag, New York, N.Y.
  28. ↑ Belovsky, G.E. and J.B. Slade. (2000). "Insect herbivory accelerates nutrient cycling and increases plant production". In: Proceedings of the national academy of sciences (USA). 97:14412-14417.
  29. 1 2 Frank et al. 2005.
  30. ↑ Hunter, M.D. (2001). "Insect population dynamics meets ecosystem ecology: effects of herbivory on soil nutrient dynamics". In: Agricultural and Forest Entomology 3:77-84.
  31. ↑ Swank, W.T., Waide, J.B., Crossley, D.A., and Todd R.L. (1981). "Insect defoliation enhances nitrate export from forest ecosystems". In: Oecologia 51:297-299.
  32. ↑ Stadler, B., Solinger, St., and Michalzik, B. (2001). "Insect herbivores and the nutrient flow from the canopy to the soil in coniferous and deciduous forests". In: Oecologia 126:104-113
  33. ↑ The intimate relation between ecosystem services and well-being was highlighted in the Millennium Ecosystem Assessment
  34. ↑ Ehrenfeld, J.G. and Toth, L.A. (1997). "Restoration ecology and the ecosystem perspective". in: Restoration Ecology 5:307-317.
  35. ↑ Conz, B.W. 2004. Continuity and Contestation: Conservation Landscapes in Totonicapán, Guatemala. University of Massachusetts Masters of Science thesis.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.