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Ecosystem Information

An ecosystem is a biological system consisting of all the living organisms or biotic components in a particular area and the nonliving or abiotic component with which the organisms interact, such as air, mineral soil, water and sunlight.[1] Key processes in ecosystems include the capture of light energy and carbon through photosynthesis, the transfer of carbon and energy through food webs, and the release of nutrients and carbon through decomposition.

Contents

Overview

Rainforests often have a great deal of biodiversity with many plant and animal species. This is the Gambia River in Senegal's Niokolo-Koba National Park.

An ecosystem consists of a biological community together with its abiotic environment, interacting as a system.[2] While the size of an ecosystem is not specifically defined it usually encompasses a limited, defined area[3] (although it is sometimes said that it can encompass the entire planet[4]). Ecosystems are defined by the network on interactions among organisms, and between organisms and their environment.[5] They are linked together through nutrient cycle and energy flow.[6]

Energy, water, nitrogen and soil minerals are other essential abiotic components of an ecosystem. The energy that flows through ecosystems is obtained primarily from the sun. It generally enters the system through photosynthesis, a process that also captures carbon from the atmosphere. 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 other microbes.[7]

Ecosystems are controlled both by internal and external factors. External factors, also called state factors, control the overall structure an ecosystem and the way things work within it, but are not, themselves, influenced by the ecosystem. The most important of these is climate. Climate determines the biome in which the ecosystem is embedded. Rainfall patterns and temperature seasonality determine the amount of water available to the ecosystem and the supply of energy available (by influencing photosynthesis). Parent material, the underlying geological material that gives rise to soils, determines the nature of the soils present, and influences the supply of mineral nutrients. Topography also controls ecosystem processes by affecting things like microclimate, soil development and the movement of water through a system. This may be the difference between the ecosystem present in wetland situated in a small depression on the landscape, and that present on an adjacent steep hillside.[8]

Other external factors that play an important role in ecosystem functioning include time and potential biota. Time plays a role in the development of soil from bare rock and the recovery of a community from disturbance. Similarly, the set of organisms that can potentially be present in an area can also have a major impact on 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.[8] Similarly, the introduction of non-native species 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 feedback loops. While the resource 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. Human 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.[8]

The number of species making up such a community may vary from a myriad to a single species such as Desulforudis. In a typical ecosystem, plants and other photosynthetic organisms are the producers that provide the food.[9] Ecosystems usually form a number of food webs.[10]

History and development

Arthur Tansley, a British ecologist, was the first person to use the term "ecosystem" in a published work.[fn 1][11] Tansley devised the concept to draw attention to the importance of transfers of materials between organisms and their environment.[12] Tansley 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".[13] Tansley regarded ecosystems not simply as natural units, but as mental isolates.[13] Tansley later[14] defined the spatial extent of ecosystems using the term ecotope.

G. Evelyn Hutchinson, a pioneering limnologist who was a contemporary of Tansley's, combined Charles Elton's ideas about trophic ecology with those of Russian geochemist Vladimir Vernadsky to suggest that mineral nutrient availability in a lake much algal production which would, in turn, limit the abundance of animals that feed on algae. Raymond Lindeman took these ideas one step further to suggest that the flow of energy through a lake was the primary driver of the ecosystem. Hutchinson's students, brothers Howard T. Odum and Eugene P. Odum, further developed a "systems approach" to the study of ecosystems, allowing them to study the flow of energy and material through ecological systems.[12]

Ecosystem processes

Energy and carbon enter ecosystems through photosynthesis, are incorporated into living tissue, transferred to other organisms that feed on the living and dead plant matter, and eventually released through respiration.[15]

Primary production

Global oceanic and terrestrial phototroph abundance, from September 1997 to August 2000. As an estimate of autotroph biomass, it is only a rough indicator of primary production potential, and not an actual estimate of it. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center and ORBIMAGE. Main article: Primary production

Primary production is the production of organic matter from inorganic carbon sources. Overwhelmingly, this occurs through photosynthesis. 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, soil carbon and fossil fuels. It also drives the carbon cycle, which influences global climate via the greenhouse effect.

Through the process of photosynthesis, plants capture energy from light and use it to combine carbon dioxide and water to produce carbohydrates and oxygen. The photosynthesis carried out by all the plants in an ecosystem is called the gross primary production (GPP).[16] About 48–60% of the GPP is consumed in plant respiration. The remainder, that portion of GPP that is not used up by respiration, is known as Net Primary Production (NPP).[15] Total photosynthesis, is limited by a range of environmental factors. These include the amount of light available, the amount of leaf 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 chloroplasts to support photosynthesis, the availability of water, and the availability of suitable temperatures for carrying out photosynthesis.[16]

Energy flow

Left: Energy flow diagram of a frog. The frog represents a node in an extended food web. The energy ingested is utilized for metabolic processes and transformed into biomass. The energy flow continues on its path if the frog is ingested by predators, parasites, or as a decaying carcass in soil. This energy flow diagram illustrates how energy is lost as it fuels the metabolic process that transform the energy and nutrients into biomass. Right: An expanded three link energy food chain (1. plants, 2. herbivores, 3. carnivores) illustrating the relationship between food flow diagrams and energy transformity. The transformity of energy becomes degraded, dispersed, and diminished from higher quality to lesser quantity as the energy within a food chain flows from one trophic species into another. Abbreviations: I=input, A=assimilation, R=respiration, NU=not utilized, P=production, B=biomass.[17] Main article: Energy flow (ecology) See also: Food web and Trophic level

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 detritus. In terrestrial ecosystems, roughly 90% of the NPP ends up being broken down by decomposers. 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 aquatic systems, the proportion of plant biomass that gets consumed by herbivores is much higher.[18] In trophic systems photosynthetic organisms are the primary producers. The organisms that consume their tissues are called primary consumers or secondary producers—herbivores. Organisms which feed on microbes (bacteria and fungi) are termed microbivores. Animals that feed on primary consumers—carnivores—are secondary consumers. Each of these constitutes a trophic level.[18] The sequence of consumption—from plant to herbivore, to carnivore—forms a food chain. 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 are 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, are known as food webs.[18]

Decomposition

See also: Decomposition

The carbon and nutrients in dead organic matter are broken down by a group of processes known as decomposition. 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 photosynthesis. In the absence of decomposition, dead organic matter would accumulate in an ecosystem and nutrients and carbon dioxide would be depleted.[19] Approximately 90% of terrestrial NPP goes directly from plant to decomposer.[18]

Decomposition processes can be separated into three categories of processes—leaching, 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).[19] Newly shed leaves and newly dead animals have high concentrations of water-soluble components, and include sugars, amino acids and mineral nutrients. Leaching is more important in wet environments, and much less important in dry ones.[19]

Fragmentation processes break organic material into smaller pieces, exposing new surfaces for colonization by microbes. Freshly shed leaf litter may be inaccessible due to an outer layer of cuticle or bark, and cell contents are protected by a cell wall. Newly dead animals may be covered by an exoskeleton. Fragmentation processes, which break through these protective layers, accelerate the rate of microbial decomposition.[19] Animals fragment detritus as the hunt for food, as does passage through the gut. Freeze-thaw cycles and cycles of wetting and drying also fragment dead material.[19]

The chemical alteration of dead organic matter is primarily achieves through bacterial and fungal action. Fungal hyphae produce enzymes which can break through the tough outer structures surrounding dead plant material. They also produce enzymes which break down lignin, gaining access to both cell contents and to the nitrogen in the lignin. Fungi can transfer carbon and nitrogen through its hyphal network, and thus, unlike bacteria, they are not dependent solely on locally available resources.[19]

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.[20] Temperature controls the rate of microbial respiration; the higher the temperature, the faster 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.[20]

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 wetlands), 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. When the rains return and soils become wet, the osmotic gradient between the bacterial cells and the soil water causes the cells to gain water quickly. Under these conditions, many bacterial cells burst, releasing a pulse of nutrients.[20] Decomposition rates also tend to be slower in acidic soils.[20] Soils which are rich in clay minerals tend to have lower decomposition rates, and thus, higher levels of organic matter.[20] The smaller particles of clay result in a larger surface area that can hold water. The higher the water content of a soil, the lower the oxygen content[21] and consequently, the lower the rate of decomposition. Clay minerals also bind particles of organic material to their surface, making them less accessibly to microbes.[20] Soil disturbance like tilling increase decomposition by increasing the amount of oxygen in the soil and by exposing new organic matter to soil microbes.[20]

The quality and quantity of the material available to decomposers is another major factor that influences the rate of decomposition. Substances like sugars and amino acids decompose readily and are considered "labile". Cellulose and hemicellulose, which are broken down more slowly, are "moderately labile". Compounds which are more resistant to decay, like lignin or cutin, are considered "recalcitrant".[20] Litter with a higher proportion of labile compounds decomposes much more rapidly than does litter with a higher proportion of recalcitrant material. Consequently, dead animals decompose more rapidly than dead leaves, which themselves decompose more rapidly than fallen branches.[20] As organic material in the soil ages, its quality decreases. The more labile compounds decompose quickly, leaving and increasing proportion of recalcitrant material. Microbial cell walls also contain a recalcitrant materials like chitin, and these also accumulate as the microbes die, further reducing the quality of older soil organic matter.[20]

Nutrient cycling

Biological nitrogen cycling. See also: Nutrient cycle

Ecosystems continually exchange energy and carbon with the wider environment; 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 nitrogen fixation, is deposited through precipitation, dust, gases or is applied as fertilizer.[22] Since most terrestrial ecosystems are nitrogen-limited, nitrogen cycling is an important control on ecosystem production.[22]

Until modern times, nitrogen fixation was the major source of nitrogen for ecosystems. Nitrogen fixing bacteria either live symbiotically with plants, or live freely in the soil. The energetic cost is high for plants which support nitrogen-fixing symbionts—as much as 25% of GPP when measured in controlled conditions. Many members of the legume plant family support nitrogen-fixing symbionts. Some cyanobacteria are also capable of nitrogen fixation. These are phototrophs, which carry out photosynthesis. Like other nitrogen-fixing bacteria, they can either be free-living or have symbiotic relationships with plants.[22] Other sources of nitrogen include acid deposition produced through the combustion of fossil fuels, ammonia gas which evaporates from agricultural fields which have had fertilizers applied to them, and dust.[22] Anthropogenic nitrogen inputs account for about 80% of all nitrogen fluxes in ecosystems.[22]

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 ammonium ions into the soil. This process is known as nitrogen mineralization. Others convert ammonium to nitrite and nitrate ions, a process known as nitrification. Nitric oxide and nitrous oxide are also produced during nitrification.[22] Under nitrogen-rich and oxygen-poor conditions, nitrates and nitrites are converted to nitrogen gas, a process known as denitrification.[22]

Other important nutrients include phosphorus, sulfur, calcium, potassium, magnesium and manganese.[23] Phosphorus enters ecosystems through weathering. As ecosystems age this supply diminishes, making phosphorus-limitation more common in older landscapes (especially in the tropics).[23] Calcium and sulfur are produced by weathering, but acid deposition is an important source of sulfur in many ecosystems. Magnesium and manganese are also 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.[23]

Function and biodiversity

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Savanna at Ngorongoro Conservation Area, Tanzania. See also: Biodiversity

From an anthropocentric point of view, some people perceive ecosystems as production units that produce goods and services, such as wood by forest ecosystems and grass for cattle by natural grasslands. Meat from wild animals, often referred to as bush meat in Africa, has proven to be extremely successful under well-controlled management schemes in South Africa and Kenya. Much less successful has been the discovery and commercialization of substances of wild organism for pharmaceutical purposes. Services derived from ecosystems are referred to as ecosystem services. They may include

  1. Facilitating the enjoyment of nature, which may generate many forms of income and employment in the tourism sector, often referred to as eco-tourisms,
  2. Water retention, thus facilitating a more evenly distributed release of water,
  3. Soil protection, open-air laboratory for scientific research, etc.
The side of a tide pool showing sea stars (Dermasterias), sea anemones (Anthopleura) and sea sponges in Santa Cruz, California.

A greater degree of species or biological diversity – commonly referred to as Biodiversity – of an ecosystem may contribute to greater resilience of an ecosystem, because there are more species present at a location to respond to change and thus "absorb" or reduce its effects. “Some theories predict that biodiversity will promote ecosystem integrity in changing climates, because high diversity ensures that functional groups will retain at least one species able to tolerate altered condition."[24] This reduces the effect before the ecosystem's structure is fundamentally changed to a different state. One hypothesis about this is the Rivet Poper Hypothesis. According to Paul and Anne Ehrlich “the diversity of life is something like the rivets on an airplane. Each species plays a small but significant role in the working of the whole, and the loss of any rivet weakens the plane by a small but measurable amount. Pop too many rivets and the plane will crash that is, some vital function will collapse."[25] They are saying if too many species die out then some sort of vital function of the ecosystem such as a food web would collapse causing the ecosystem to fail. However rivets come in different sizes and have different critical functions in construction, when thinking about species as rivets the variety and distribution in the overall structure is important.

This is not universally the case and there is no proven relationship between the species diversity of an ecosystem and its ability to provide goods and services on a sustainable level: Humid tropical forests produce very few goods and direct services and are extremely vulnerable to change, while many temperate forests readily grow back to their previous state of development within a lifetime after felling or a forest fire. Some grasslands have been sustainably exploited for thousands of years (Mongolia, Africa, European peat and mooreland communities).

The study of ecosystems

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Forest on San Juan Island Loch Lomond in Scotland forms a relatively isolated ecosystem. The fish community of this lake has remained unchanged over a very long period of time.[26]

Ecosystem dynamics

Introduction of new elements, whether biotic or abiotic, into an ecosystem tend to have a disruptive effect. In some cases, this can lead to ecological collapse or "trophic cascading" and the death of many species within the ecosystem. Under this deterministic vision, the abstract notion of ecological health attempts to measure the robustness and recovery capacity for an ecosystem; i.e. how far the ecosystem is away from its steady state.

Often, however, ecosystems have the ability to rebound from a disruptive agent. The difference between collapse or a gentle rebound is determined by two factors—the toxicity of the introduced element and the resiliency of the original ecosystem.

Ecosystems are primarily governed by stochastic (chance) events, the reactions these events provoke on non-living materials and the responses by organisms to the conditions surrounding them. Thus, an ecosystem results from the sum of individual responses of organisms to stimuli from elements in the environment.The presence or absence of populations merely depends on reproductive and dispersal success, and population levels fluctuate in response to stochastic events. As the number of species in an ecosystem is higher, the number of stimuli is also higher. Since the beginning of life organisms have survived continuous change through natural selection of successful feeding, reproductive and dispersal behavior. Through natural selection the planet's species have continuously adapted to change through variation in their biological composition and distribution. Mathematically it can be demonstrated that greater numbers of different interacting factors tend to dampen fluctuations in each of the individual factors.

Spiny forest at Ifaty, Madagascar, featuring various Adansonia (baobab) species, Alluaudia procera (Madagascar ocotillo) and other vegetation.

Given the great diversity among organisms on earth, most ecosystems only changed very gradually, as some species would disappear while others would move in. Locally, sub-populations continuously go extinct, to be replaced later through dispersal of other sub-populations. Stochastists do recognize that certain intrinsic regulating mechanisms occur in nature. Feedback and response mechanisms at the species level regulate population levels, most notably through territorial behaviour. Andrewatha and Birch[27] suggest that territorial behaviour tends to keep populations at levels where food supply is not a limiting factor. Hence, stochastists see territorial behaviour as a regulatory mechanism at the species level but not at the ecosystem level. Thus, in their vision, ecosystems are not regulated by feedback and response mechanisms from the ecosystem itself and there is no such thing as a balance of nature.

If ecosystems are governed primarily by stochastic processes, through which its subsequent state would be determined by both predictable and random actions, they may be more resilient to sudden change than each species individually. In the absence of a balance of nature, the species composition of ecosystems would undergo shifts that would depend on the nature of the change, but entire ecological collapse would probably be infrequent events.

The theoretical ecologist Robert Ulanowicz has used information theory tools to describe the structure of ecosystems, emphasizing mutual information (correlations) in studied systems. Drawing on this methodology and prior observations of complex ecosystems, Ulanowicz depicts approaches to determining the stress levels on ecosystems and predicting system reactions to defined types of alteration in their settings (such as increased or reduced energy flow, and eutrophication.[28]

Arctic tundra on Wrangel Island, Russia.

In addition, Eric Sanderson has developed the Muir web, based on experience on the Mannahatta project. This graphical schematic shows how different species are connected to each other, not only regarding their position in the food chain, but also regarding other services, i.e. provisioning of shelter, ...[29][30]

See also: Relational order theories, as to fundamentals of life organization

Ecosystem ecology

Ecosystem ecology is the integrated study of biotic and 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. Ecosystem ecology examines physical and biological structure and examines how these ecosystem characteristics interact.

Ecosystem services

Main article: Ecosystem services

Ecosystem services are “fundamental life-support services upon which human civilization depends,”i and can be direct or indirect. Examples of direct ecosystem services are: pollination, wood and erosion prevention. Indirect services could be considered climate moderation, nutrient cycles and detoxifying natural substances. The services and goods an ecosystem provides are often undervalued as many of them are without market value.[31] Broad examples include:

Biomes

Map of Terrestrial biomes classified by vegetation. Main article: Biome

Biomes are a classification of globally similar areas, including ecosystems, such as ecological communities of plants and animals, soil organisms and climatic conditions. classification of biomes is:

  1. Terrestrial (land) biomes.
  2. Freshwater biomes.
  3. Marine biomes.

Classification

Summer field in Belgium (Hamois). The blue flower is Centaurea cyanus and the red one a Papaver rhoeas. The High Peaks Wilderness Area in the 6,000,000-acre (2,400,000 ha) Adirondack Park is an example of a diverse ecosystem. Flora of Baja California Desert, Cataviña region, Mexico.

Ecosystems have become particularly important politically, since the Convention on Biological Diversity (CBD) – ratified by 192 countries – defines "the protection of ecosystems, natural habitats and the maintenance of viable populations of species in natural surroundings"[34] as a commitment of ratifying countries. This has created the political necessity to spatially identify ecosystems and somehow distinguish among them. The CBD defines an "ecosystem" as a "dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit".

With the need of protecting ecosystems, the political need arose to describe and identify them efficiently. Vreugdenhil et al. argued that this could be achieved most effectively by using a physiognomic-ecological classification system, as ecosystems are easily recognizable in the field as well as on satellite images. They argued that the structure and seasonality of the associated vegetation, or flora, complemented with ecological data (such as elevation, humidity, and drainage), are each determining modifiers that separate partially distinct sets of species. This is true not only for plant species, but also for species of animals, fungi and bacteria. The degree of ecosystem distinction is subject to the physiognomic modifiers that can be identified on an image and/or in the field. Where necessary, specific fauna elements can be added, such as seasonal concentrations of animals and the distribution of coral reefs.

Several physiognomic-ecological classification systems are available:

Several aquatic classification systems are available, and an effort is being made by the United States Geological Survey (USGS) and the Inter-American Biodiversity Information Network (IABIN) to design a complete ecosystem classification system that will cover both terrestrial and aquatic ecosystems.

From a philosophy of science perspective, ecosystems are not discrete units of nature that simply can be identified using the most "correct" type of classification approach. In agreement with the definition by Tansley ("mental isolates"), any attempt to delineate or classify ecosystems should be explicit about the observer/analyst input in the classification including its normative rationale.

Two Giant Sequoias, Sequoia National Park. Note the large fire scar at the base of the right-hand tree; fires do not kill the trees but do remove competing thin-barked species, and aid Giant Sequoia regeneration.

Ecosystem legal rights

Ecuador's new constitution of 2008 is the first in the world to recognize legally enforceable Rights of Nature, or ecosystem rights.[39]

The borough of Tamaqua, Pennsylvania passed a law giving ecosystems legal rights. The ordinance establishes that the municipal government or any Tamaqua resident can file a lawsuit on behalf of the local ecosystem.[40] Other townships, such as Rush, followed suit and passed their own laws.[41]

This is part of a growing body of legal opinion proposing 'wild law'. Wild law, a term coined by Cormac Cullinan (a lawyer based in South Africa), would cover birds and animals, rivers and deserts.[42][43]

Examples of ecosystems

A freshwater ecosystem in Gran Canaria, an island of the Canary Islands.

See also

Earth_sciences portal
Ecology portal
Environment portal
Weather portal
Sustainable Development portal

Notes

  1. ^ The term ecosystem was actually coined by Arthur Roy Clapham, who came up with the word at Tansley's request.(Willis 1997)

References

Sea urchins like this purple sea urchin can damage kelp forest ecosystems by chewing through kelp holdfasts Tundra in Greenland
  1. ^ Chapin et al. (2002), p. 380
  2. ^ Tansley (1934); Molles (1999), p. 482; Chapin et al. (2002), p. 380; Schulze et al. (2005); p. 400; Gurevitch et al. (2006), p. 522; Smith & Smith 2012, p. G-5
  3. ^ Chapin et al. (2002), p. 380; Schulze et al. (2005); p. 400
  4. ^ Willis (1997), p.269; Chapin et al. (2002), p. 5; Krebs (2009). p. 572
  5. ^ Schulze et al. (2005), p.400
  6. ^ Odum, EP (1971) Fundamentals of ecology, third edition, Saunders New York
  7. ^ Chapin et al. (2002), p. 10
  8. ^ a b c Chapin et al. (2002), pp. 11–13
  9. ^ ”Biology Concepts & Connections Sixth Edition”, Campbell, Neil A. (2009), page 2, 3 and G-9. Retrieved 2010-06-14.
  10. ^ (1996) Geosystems: An Introduction to Physical Geography. Prentice Hall Inc.
  11. ^ Willis (1997)
  12. ^ a b Chapin et al. (2002), pp. 7–11)
  13. ^ a b Tansley (1935)
  14. ^ Tansley, AG (1939) The British islands and their vegetation. Volume 1 of 2. Cambridge University Press, United. Kingdom. 484 pg.
  15. ^ a b Chapin et al. (2002), pp. 123–150
  16. ^ a b Chapin et al. (2002), pp. 97–104
  17. ^ Odum, H. T. (1988). "Self-organization, transformity, and information". Science 242 (4882): 1132–1139. doi:10.1126/science.242.4882.1132. JSTOR 1702630.
  18. ^ a b c d Chapin et al. (2002) pp. 244–264
  19. ^ a b c d e f Chapin et al. (2002), pp. 151–157
  20. ^ a b c d e f g h i j Chapin et al. (2002), pp. 159–174
  21. ^ Chapin et al. (2002), pp. 61–67
  22. ^ a b c d e f g Chapin et al. (2002), pp. 197-215
  23. ^ a b c Chapin et al. (2002), pp. 215-222
  24. ^ Owen L. Petchey, [1], Proquest Research Library, Nov 4th 1999
  25. ^ Yvonne Baskin,[2], “Proquest Research Library”, Nov 1994
  26. ^ Adams, C.E. (1994). "The fish community of Loch Lomond, Scotland : its history and rapidly changing status". Hydrobiologia 290 (1–3): 91–102. doi:10.1007/BF00008956. http://cat.inist.fr/?aModele=afficheN&cpsidt=3302548.
  27. ^ Andrewatha, HG and LC Birch (1954) The distribution and abundance of animals. University of Chicago Press, Chicago, IL
  28. ^ Robert Ulanowicz (1997). Ecology, the Ascendant Perspective. Columbia Univ. Press. ISBN 0-231-10828-1.
  29. ^ Muir web
  30. ^ Muir web definition
  31. ^ Costanza, R.; d'Arge, R.; de Groot, R.; Farber, S.; Grasso, M.; Hannon, B.; et al., Karin; Naeem, Shahid et al (1997). "The value of the world’s ecosystem services and natural capital". Nature 387 (6630): 253–260. doi:10.1038/387253a0. http://www.uvm.edu/giee/publications/Nature_Paper.pdf.
  32. ^ Martin Dallimer et al (2012), 'Biodiversity and the feel-good factor: Understanding associations between self-reported human well-being and species richness', doi:10.1525/bio.2012.62.1.9 [3]
  33. ^ Millennium Ecosystem Assessment, 2005. Ecosystems and Human Well-being: Biodiversity Synthesis. World Resources Institute, Washington, DC. [4]
  34. ^ United Nations Environment Programme. Convention on Biological Diversity. June 1992. UNEP Document no. Na.92-78. Reprint
  35. ^ Möller-Dombois & Ellenberg: "A Tentative Physiognomic-Ecological Classification of Plant Formations of the Earth".
  36. ^ Map of the ecosystems of Central America, WICE 2005. Retrieved 30 August 2008.
  37. ^ Antonio Di Gregorio & Louisa J.M. Jansen (2007). Land Cover Classification System (LCCS): Classification Concepts and User Manual. Retrieved 30 August 2008.
  38. ^ Garrison, George A.; Bjugstad, A. J.; Duck, D. A.; Lewis, M. E.; and Smith, D. R. (1977) Vegetation and environmental features of forest and range ecosystems (Forest Service Handbook Number 465) United States Department of Agriculture, Washington, D.C., OCLC 3359594 worldcat.org
  39. ^ The Community Environmental Legal Defense Fund: about the New Constitution 2008 The Community Environmental Legal Defense Fund, Retrieved 2009-09-07
  40. ^ Tamaqua Law Recognizes Rights of Nature
  41. ^ Rush Township Strips Sludge Corporation "Rights"
  42. ^ On Thin Ice
  43. ^ Earthly rights

Literature cited

Further reading

External links

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