Ecosystem: Difference between revisions

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Ecosystems are controlled by external and internal [[Environmental factor|factors]]. External factors—including [[climate]]—control the ecosystem's structure, but are not influenced by it. By contrast, internal factors control and are controlled by ecosystem processes; these include [[decomposition]], the types of species present, root competition, shading, disturbance, and succession. While external factors generally determine which [[Resource (biology)|resource]] inputs an ecosystem has, their availability within the ecosystem is controlled by internal factors. Ecosystems are [[wikt:dynamic|dynamic]], subject to periodic disturbances and always in the process of recovering from past disturbances. The tendency of an ecosystem to remain close to its equilibrium state, is termed its [[resistance (ecology)|resistance]]. Its capacity to absorb disturbance and reorganize, while undergoing change so as to retain essentially the same function, structure, identity, is termed its [[ecological resilience]].

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. [[Biome]]s are general classes or categories of ecosystems. However, there is no clear distinction between biomes and ecosystems. [[Ecological classification|Ecosystem classifications]] are specific kinds of ecological classifications that consider all four elements of the definition of ecosystems: a biotic component, an [[abiotic]] complex, the interactions between and within them, and the physical space they occupy. Biotic factors are living things; such as plants, while abiotic are non-living components; such as soil. Plants allow energy to enter the system through [[photosynthesis]], building up plant tissue. Animals play an important role in the movement of [[matter]] and energy through the system, by feeding on plants and one another. They also influence the quantity of plant and [[Microbe|microbial]] [[Biomass (ecology)|biomass]] present. By breaking down dead [[organic matter]], [[decomposer]]s 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.

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. [[Biome]]s are general classes or categories of ecosystems. However, there is no clear distinction between biomes and ecosystems. [[Ecological classification|Ecosystem classifications]] are specific kinds of ecological classifications that consider all four elements of the definition of ecosystems: a biotic component, an [[abiotic]] complex, the interactions between and within them, and the physical space they occupy. Biotic factors are living things, such as plants, while abiotic factors are non-living components, such as soil. Plants allow energy to enter the system through [[photosynthesis]], building up plant tissue. Animals play an important role in the movement of [[matter]] and energy through the system, by feeding on plants and one another. They also influence the quantity of plant and [[Microbe|microbial]] [[Biomass (ecology)|biomass]] present. By breaking down dead [[organic matter]], [[decomposer]]s 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.

Ecosystems provide a variety of goods and services upon which people depend, and may be part of. Ecosystem goods include the "tangible, material products" of ecosystem processes such as water, food, fuel, construction material, and [[medicinal plants]]. [[Ecosystem services]], on the other hand, are generally "improvements in the condition or location of things of value". These include ~~things like the~~ maintenance of [[Water cycle|hydrological cycles]], cleaning air and water, the maintenance of oxygen in the atmosphere, crop [[pollination]] ~~and even things like beauty~~, ~~inspiration~~ and opportunities for research. Many ecosystems become degraded through human impacts, such as [[Erosion|soil loss]], [[Air pollution|air]] and [[water pollution]], [[habitat fragmentation]], [[Interbasin transfer|water diversion]], [[Wildfire suppression|fire suppression]], and [[introduced species]] and [[invasive species]]. These threats can lead to abrupt transformation of the ecosystem or to gradual disruption of biotic processes and degradation of [[Abiotic component|abiotic]] conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered [[Ecosystem collapse|"collapsed]]". [[Restoration ecology|Ecosystem restoration]] can contribute to achieving the [[Sustainable Development Goals]].

Ecosystems provide a variety of goods and services upon which people depend, and may be part of. Ecosystem goods include the "tangible, material products" of ecosystem processes such as water, food, fuel, construction material, and [[medicinal plants]]. [[Ecosystem services]], on the other hand, are generally "improvements in the condition or location of things of value". These include maintenance of [[Water cycle|hydrological cycles]], cleaning air and water, the maintenance of oxygen in the atmosphere, crop [[pollination]], and opportunities for research. Many ecosystems become degraded through human impacts, such as [[Erosion|soil loss]], [[Air pollution|air]] and [[water pollution]], [[habitat fragmentation]], [[Interbasin transfer|water diversion]], [[Wildfire suppression|fire suppression]], and [[introduced species]] and [[invasive species]]. These threats can lead to abrupt transformation of the ecosystem or to gradual disruption of biotic processes and degradation of [[Abiotic component|abiotic]] conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered [[Ecosystem collapse|"collapsed]]". [[Restoration ecology|Ecosystem restoration]] can contribute to achieving the [[Sustainable Development Goals]].

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[[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.<ref name="Chapin-2011e" />{{rp|157}} 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 ecosystem]]s, the vast majority of the net primary production ends up being broken down by [[decomposition|decomposers]]. The remainder is consumed by animals while still alive and enters the plant-based trophic system. After plants and animals die, the organic matter contained in them enters the detritus-based trophic system.<ref name="Chapin-2011i">{{Cite book|last=Chapin|first=F. Stuart III|title=Principles of terrestrial ecosystem ecology|date=2011|publisher=Springer|others=P. A. Matson, Peter Morrison Vitousek, Melissa C. Chapin|isbn=978-1-4419-9504-9|edition=2nd|location=New York|chapter=Chapter 10: Trophic Dynamics|oclc=755081405}}</ref>

[[Ecosystem respiration]] is the sum of [[Cellular respiration|respiration]] by all living organisms (plants, animals, and decomposers) in the ecosystem.<ref>{{Cite journal|last1=Yvon-Durocher|first1=Gabriel|last2=Caffrey|first2=Jane M.|last3=Cescatti|first3=Alessandro|last4=Dossena|first4=Matteo|last5=Giorgio|first5=Paul del|last6=Gasol|first6=Josep M.|last7=Montoya|first7=José M.|last8=Pumpanen|first8=Jukka|last9=Staehr|first9=Peter A.|date=2012|title=Reconciling the temperature dependence of respiration across timescales and ecosystem types|journal=Nature|language=En|volume=487|issue=7408|pages=472–476|bibcode=2012Natur.487..472Y|doi=10.1038/nature11205|issn=0028-0836|pmid=22722862|s2cid=4422427}}</ref> [[Net ecosystem production]] is the difference between [[Primary production|gross primary production]] (GPP) and ecosystem respiration.<ref name="Lovett-2006">{{Cite journal|last1=Lovett|first1=Gary M.|last2=Cole|first2=Jonathan J.|last3=Pace|first3=Michael L.|date=2006|title=Is Net Ecosystem Production Equal to Ecosystem Carbon Accumulation?|journal=Ecosystems|language=en|volume=9|issue=1|pages=152–155|doi=10.1007/s10021-005-0036-3|bibcode=2006Ecosy...9..152L |issn=1435-0629|s2cid=5890190}}</ref> In the absence of disturbance, net ecosystem production is equivalent to the net carbon accumulation in the ecosystem.

[[Ecosystem respiration]] is the sum of [[Cellular respiration|respiration]] by all living organisms (plants, animals, and decomposers) in the ecosystem.<ref>{{Cite journal|last1=Yvon-Durocher|first1=Gabriel|last2=Caffrey|first2=Jane M.|last3=Cescatti|first3=Alessandro|last4=Dossena|first4=Matteo|last5=Giorgio|first5=Paul del|last6=Gasol|first6=Josep M.|last7=Montoya|first7=José M.|last8=Pumpanen|first8=Jukka|last9=Staehr|first9=Peter A.|date=2012|title=Reconciling the temperature dependence of respiration across timescales and ecosystem types|journal=Nature|language=En|volume=487|issue=7408|pages=472–476|bibcode=2012Natur.487..472Y|doi=10.1038/nature11205|issn=0028-0836|pmid=22722862|s2cid=4422427}}</ref> [[Net ecosystem production]] is the difference between [[Primary production|gross primary production]] (GPP) and ecosystem respiration.<ref name="Lovett-2006">{{Cite journal|last1=Lovett|first1=Gary M.|last2=Cole|first2=Jonathan J.|last3=Pace|first3=Michael L.|date=2006|title=Is Net Ecosystem Production Equal to Ecosystem Carbon Accumulation?|journal=Ecosystems|language=en|volume=9|issue=1|pages=152–155|doi=10.1007/s10021-005-0036-3|bibcode=2006Ecosy...9..152L |issn=1435-0629|s2cid=5890190 |url=https://figshare.com/articles/journal_contribution/24840588 }}</ref> In the absence of disturbance, net ecosystem production is equivalent to the net carbon accumulation in the ecosystem.

Energy can also be released from an ecosystem through disturbances such as [[wildfire]] or transferred to other ecosystems (e.g., from a forest to a stream to a lake) by [[erosion]].

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Ecosystems are dynamic entities. They are subject to periodic disturbances and are always in the process of recovering from past disturbances.<ref name="Chapin-2011k" />{{rp|347}} When a [[perturbation (biology)|perturbation]] 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 [[resistance (ecology)|resistance]]. The capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity, and feedbacks is termed its [[ecological resilience]].<ref>{{Cite book|title=Principles of ecosystem stewardship: resilience-based natural resource management in a changing world|date=2009|publisher=Springer|editor-first1=F. Stuart III |editor-last1=Chapin |editor-first2=Gary P. |editor-last2=Kofinas |editor-first3=Carl |editor-last3=Folke |editor-first4=Melissa C. |editor-last4=Chapin|isbn=978-0-387-73033-2|edition=1st|location=New York|oclc=432702920}}</ref><ref>{{Cite journal|last1=Walker|first1=Brian|last2=Holling|first2=C. S.|last3=Carpenter|first3=Stephen R.|last4=Kinzig|first4=Ann P.|date=2004|title=Resilience, Adaptability and Transformability in Social-ecological Systems|url=https://www.ecologyandsociety.org/vol9/iss2/art5/|journal=Ecology and Society|language=en|volume=9|issue=2|pages=art5|doi=10.5751/ES-00650-090205 |doi-access=free |issn=1708-3087|hdl=10535/3282|hdl-access=free|access-date=2021-07-23|archive-date=2019-05-17|archive-url=https://web.archive.org/web/20190517073955/https://www.ecologyandsociety.org/vol9/iss2/art5/|url-status=live}}</ref> Resilience thinking also includes humanity as an integral part of the [[biosphere]] where we are dependent on [[ecosystem services]] for our survival and must build and maintain their natural capacities to withstand shocks and disturbances.<ref>{{Cite web|last=Simonsen|first=S.H. |publisher=Stockholm Resilience Centre |title=Applying Resilience Thinking|url=https://whatisresilience.org/wp-content/uploads/2016/04/Applying_resilience_thinking.pdf|url-status=live|archive-url=https://web.archive.org/web/20171215163627/http://whatisresilience.org:80/wp-content/uploads/2016/04/Applying_resilience_thinking.pdf |archive-date=2017-12-15 }}</ref> Time plays a central role over a wide range, for example, in the slow development of soil from bare rock and the faster [[ecological succession|recovery of a community from disturbance]].<ref name="Chapin-2011e" />{{rp|67}}

Ecosystems are dynamic entities. They are subject to periodic disturbances and are always in the process of recovering from past disturbances.<ref name="Chapin-2011k" />{{rp|347}} When a [[perturbation (biology)|perturbation]] 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 [[resistance (ecology)|resistance]]. The capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity, and feedbacks is termed its [[ecological resilience]].<ref>{{Cite book|title=Principles of ecosystem stewardship: resilience-based natural resource management in a changing world|date=2009|publisher=Springer|editor-first1=F. Stuart III |editor-last1=Chapin |editor-first2=Gary P. |editor-last2=Kofinas |editor-first3=Carl |editor-last3=Folke |editor-first4=Melissa C. |editor-last4=Chapin|isbn=978-0-387-73033-2|edition=1st|location=New York|oclc=432702920}}</ref><ref>{{Cite journal|last1=Walker|first1=Brian|last2=Holling|first2=C. S.|last3=Carpenter|first3=Stephen R.|last4=Kinzig|first4=Ann P.|date=2004|title=Resilience, Adaptability and Transformability in Social-ecological Systems|url=https://www.ecologyandsociety.org/vol9/iss2/art5/|journal=Ecology and Society|language=en|volume=9|issue=2|pages=art5|doi=10.5751/ES-00650-090205 |bibcode=2004EcSoc...9Tar.5W |doi-access=free |issn=1708-3087|hdl=10535/3282|hdl-access=free|access-date=2021-07-23|archive-date=2019-05-17|archive-url=https://web.archive.org/web/20190517073955/https://www.ecologyandsociety.org/vol9/iss2/art5/|url-status=live}}</ref> Resilience thinking also includes humanity as an integral part of the [[biosphere]] where we are dependent on [[ecosystem services]] for our survival and must build and maintain their natural capacities to withstand shocks and disturbances.<ref>{{Cite web|last=Simonsen|first=S.H. |publisher=Stockholm Resilience Centre |title=Applying Resilience Thinking|url=https://whatisresilience.org/wp-content/uploads/2016/04/Applying_resilience_thinking.pdf|url-status=live|archive-url=https://web.archive.org/web/20171215163627/http://whatisresilience.org:80/wp-content/uploads/2016/04/Applying_resilience_thinking.pdf |archive-date=2017-12-15 }}</ref> Time plays a central role over a wide range, for example, in the slow development of soil from bare rock and the faster [[ecological succession|recovery of a community from disturbance]].<ref name="Chapin-2011e" />{{rp|67}}

[[Disturbance (ecology)|Disturbance]] also plays an important role in ecological processes. [[F. Stuart Chapin III|F. Stuart Chapin]] and coauthors define disturbance as "a relatively discrete event in time that removes plant biomass".<ref name="Chapin-2011k">{{Cite book|last=Chapin|first=F. Stuart III|title=Principles of terrestrial ecosystem ecology|date=2011|publisher=Springer|others=P. A. Matson, Peter Morrison Vitousek, Melissa C. Chapin|isbn=978-1-4419-9504-9|edition=2nd|location=New York|chapter=Chapter 12: Temporal Dynamics|oclc=755081405}}</ref>{{rp|346}} This can range from [[herbivore]] outbreaks, treefalls, fires, hurricanes, floods, [[Glacial motion|glacial advances]], to [[Types of volcanic eruptions|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 succession, a "directional change in ecosystem structure and functioning resulting from biotically driven changes in resource supply."<ref name="Chapin-2011m">{{Cite book|last=Chapin|first=F. Stuart III|title=Principles of terrestrial ecosystem ecology|date=2011|publisher=Springer|others=P. A. Matson, Peter Morrison Vitousek, Melissa C. Chapin|isbn=978-1-4419-9504-9|edition=2nd|location=New York|chapter=Glossary|oclc=755081405}}</ref>{{rp|470}}

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The frequency and severity of disturbance determine the way it affects ecosystem function. A major disturbance like a volcanic eruption or [[Glacier|glacial]] advance and retreat leave behind soils that lack plants, animals or organic matter. Ecosystems that experience such disturbances undergo [[primary succession]]. A less severe disturbance like forest fires, hurricanes or cultivation result in [[secondary succession]] and a faster recovery.<ref name="Chapin-2011k" />{{rp|348}} More severe and more frequent disturbance result in longer recovery times.

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. Longer-term changes also shape ecosystem processes. For example, the forests of eastern North America still show legacies of [[Agriculture|cultivation]] which ceased in 1850 when large areas were reverted to forests.<ref name="Chapin-2011k" />{{rp|340}} Another example is the [[methane]] production in eastern [[Siberia]]n lakes that is controlled by [[organic matter]] which accumulated during the [[Pleistocene]].<ref>{{Cite journal|last1=Walter|first1=K. M.|last2=Zimov|first2=S. A.|last3=Chanton|first3=J. P.|last4=Verbyla|first4=D.|last5=Chapin|first5=F. S.|date=2006|title=Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming|url=http://faculty.jsd.claremont.edu/emorhardt/159/pdfs/2007/Walter%20et%20al.%202006.pdf |journal=Nature|language=en|volume=443|issue=7107|pages=71–75|doi=10.1038/nature05040|pmid=16957728|bibcode=2006Natur.443...71W|s2cid=4415304 |s2cid-access=free |issn=0028-0836|access-date=2021-08-16|archive-date=Nov 23, 2011 |archive-url=https://web.archive.org/web/20111123193233/http://faculty.jsd.claremont.edu/emorhardt/159/pdfs/2007/Walter%20et%20al.%202006.pdf ~~|url-status=dead~~ }}</ref>

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. Longer-term changes also shape ecosystem processes. For example, the forests of eastern North America still show legacies of [[Agriculture|cultivation]] which ceased in 1850 when large areas were reverted to forests.<ref name="Chapin-2011k" />{{rp|340}} Another example is the [[methane]] production in eastern [[Siberia]]n lakes that is controlled by [[organic matter]] which accumulated during the [[Pleistocene]].<ref>{{Cite journal|last1=Walter|first1=K. M.|last2=Zimov|first2=S. A.|last3=Chanton|first3=J. P.|last4=Verbyla|first4=D.|last5=Chapin|first5=F. S.|date=2006|title=Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming|url=http://faculty.jsd.claremont.edu/emorhardt/159/pdfs/2007/Walter%20et%20al.%202006.pdf |journal=Nature|language=en|volume=443|issue=7107|pages=71–75|doi=10.1038/nature05040|pmid=16957728|bibcode=2006Natur.443...71W|s2cid=4415304 |s2cid-access=free |issn=0028-0836|access-date=2021-08-16|archive-date=Nov 23, 2011 |archive-url=https://web.archive.org/web/20111123193233/http://faculty.jsd.claremont.edu/emorhardt/159/pdfs/2007/Walter%20et%20al.%202006.pdf }}</ref>

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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 [[ammonification|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.<ref name="Chapin-2011h" />{{rp|277}} Under nitrogen-rich and oxygen-poor conditions, nitrates and nitrites are converted to [[nitrogen|nitrogen gas]], a process known as [[denitrification]].<ref name="Chapin-2011h" />{{rp|281}}

Mycorrhizal fungi which are symbiotic with plant roots, use carbohydrates supplied by the plants and in return transfer phosphorus and nitrogen compounds back to the plant roots.<ref>{{Cite journal|last=Bolan|first=N.S.|date=1991|title=A critical review on the role of mycorrhizal fungi in the uptake of phosphorus by plants|journal=Plant and Soil|volume=134|issue=2|pages=189–207|doi=10.1007/BF00012037|bibcode=1991PlSoi.134..189B |s2cid=44215263}}</ref><ref name="Hestrin-2019" /> This is an important pathway of organic nitrogen transfer from dead organic matter to plants. This mechanism may contribute to more than 70 Tg of annually assimilated plant nitrogen, thereby playing a critical role in global nutrient cycling and ecosystem function.<ref name="Hestrin-2019">{{Cite journal|last1=Hestrin|first1=R.|last2=Hammer|first2=E.C.|last3=Mueller|first3=C.W.|date=2019|title=Synergies between mycorrhizal fungi and soil microbial communities increase plant nitrogen acquisition|journal=Commun Biol|volume=2|~~page~~=233|doi=10.1038/s42003-019-0481-8|pmid=31263777|pmc=6588552}}</ref>

Mycorrhizal fungi which are symbiotic with plant roots, use carbohydrates supplied by the plants and in return transfer phosphorus and nitrogen compounds back to the plant roots.<ref>{{Cite journal|last=Bolan|first=N.S.|date=1991|title=A critical review on the role of mycorrhizal fungi in the uptake of phosphorus by plants|journal=Plant and Soil|volume=134|issue=2|pages=189–207|doi=10.1007/BF00012037|bibcode=1991PlSoi.134..189B |s2cid=44215263}}</ref><ref name="Hestrin-2019" /> This is an important pathway of organic nitrogen transfer from dead organic matter to plants. This mechanism may contribute to more than 70 Tg of annually assimilated plant nitrogen, thereby playing a critical role in global nutrient cycling and ecosystem function.<ref name="Hestrin-2019">{{Cite journal|last1=Hestrin|first1=R.|last2=Hammer|first2=E.C.|last3=Mueller|first3=C.W.|date=2019|title=Synergies between mycorrhizal fungi and soil microbial communities increase plant nitrogen acquisition|journal=Commun Biol|volume=2|issue=1 |article-number=233|doi=10.1038/s42003-019-0481-8|pmid=31263777|pmc=6588552 |bibcode=2019CmBio...2..233H }}</ref>

Phosphorus enters ecosystems through [[weathering]]. As ecosystems age this supply diminishes, making phosphorus-limitation more common in older landscapes (especially in the tropics).<ref name="Chapin-2011h" />{{rp|287–290}} 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.<ref name="Chapin-2011h" />{{rp|291}}

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Many ecosystems become degraded through human impacts, such as [[Erosion|soil loss]], [[Air pollution|air]] and [[water pollution]], [[habitat fragmentation]], [[Interbasin transfer|water diversion]], [[Wildfire suppression|fire suppression]], and [[introduced species]] and [[invasive species]].<ref name="Chapin-2011l" />{{rp|437}}

These threats can lead to abrupt transformation of the ecosystem or to gradual disruption of biotic processes and degradation of [[Abiotic component|abiotic]] conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered ''[[ecosystem collapse|collapsed]]'' (see also [[IUCN Red List of Ecosystems]]).<ref name="Keith-2013">{{cite journal|last1=Keith|first1=DA|last2=Rodríguez|first2=J.P.|last3=Rodríguez-Clark|first3=K.M.|last4=Aapala|first4=K.|last5=Alonso|first5=A.|last6=Asmussen|first6=M.|last7=Bachman|first7=S.|last8=Bassett|first8=A.|last9=Barrow|first9=E.G.|last10=Benson|first10=J.S.|last11=Bishop|first11=M.J.|last12=Bonifacio|first12=R.|last13=Brooks|first13=T.M.|last14=Burgman|first14=M.A.|last15=Comer|first15=P.|last16=Comín|first16=F.A.|last17=Essl|first17=F.|last18=Faber-Langendoen|first18=D.|last19=Fairweather|first19=P.G.|last20=Holdaway|first20=R.J.|last21=Jennings|first21=M.|last22=Kingsford|first22=R.T.|last23=Lester|first23=R.E.|last24=Mac Nally|first24=R.|last25=McCarthy|first25=M.A.|last26=Moat|first26=J.|last27=Nicholson|first27=E.|last28=Oliveira-Miranda|first28=M.A.|last29=Pisanu|first29=P.|last30=Poulin|first30=B.|last31=Riecken|first31=U.|last32=Spalding|first32=M.D.|last33=Zambrano-Martínez|first33=S.|title=Scientific Foundations for an IUCN Red List of Ecosystems|journal=PLOS ONE|date=2013|volume=8|issue=5|~~page~~=e62111|doi=10.1371/journal.pone.0062111|pmid=23667454|pmc=3648534|bibcode=2013PLoSO...862111K|doi-access=free}}</ref> Ecosystem collapse could be reversible and in this way differs from [[species extinction]].<ref name="Boitani-2014">{{cite journal|last1=Boitani|first1=Luigi|last2=Mace|first2=Georgina M.|last3=Rondinini|first3=Carlo|title=Challenging the Scientific Foundations for an IUCN Red List of Ecosystems|journal=Conservation Letters|doi=10.1111/conl.12111|volume=8|issue=2|date=2014|pages=125–131|url=http://discovery.ucl.ac.uk/1443166/1/conl12111.pdf|hdl=11573/624610|s2cid=62790495|hdl-access=free|access-date=2021-01-06|archive-date=2018-07-22|archive-url=https://web.archive.org/web/20180722080846/http://discovery.ucl.ac.uk/1443166/1/conl12111.pdf|url-status=live}}{{open access}}</ref> Quantitative assessments of the [[IUCN Red List of Ecosystems|risk of collapse]] are used as measures of conservation status and trends.

These threats can lead to abrupt transformation of the ecosystem or to gradual disruption of biotic processes and degradation of [[Abiotic component|abiotic]] conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered ''[[ecosystem collapse|collapsed]]'' (see also [[IUCN Red List of Ecosystems]]).<ref name="Keith-2013">{{cite journal|last1=Keith|first1=DA|last2=Rodríguez|first2=J.P.|last3=Rodríguez-Clark|first3=K.M.|last4=Aapala|first4=K.|last5=Alonso|first5=A.|last6=Asmussen|first6=M.|last7=Bachman|first7=S.|last8=Bassett|first8=A.|last9=Barrow|first9=E.G.|last10=Benson|first10=J.S.|last11=Bishop|first11=M.J.|last12=Bonifacio|first12=R.|last13=Brooks|first13=T.M.|last14=Burgman|first14=M.A.|last15=Comer|first15=P.|last16=Comín|first16=F.A.|last17=Essl|first17=F.|last18=Faber-Langendoen|first18=D.|last19=Fairweather|first19=P.G.|last20=Holdaway|first20=R.J.|last21=Jennings|first21=M.|last22=Kingsford|first22=R.T.|last23=Lester|first23=R.E.|last24=Mac Nally|first24=R.|last25=McCarthy|first25=M.A.|last26=Moat|first26=J.|last27=Nicholson|first27=E.|last28=Oliveira-Miranda|first28=M.A.|last29=Pisanu|first29=P.|last30=Poulin|first30=B.|last31=Riecken|first31=U.|last32=Spalding|first32=M.D.|last33=Zambrano-Martínez|first33=S.|title=Scientific Foundations for an IUCN Red List of Ecosystems|journal=PLOS ONE|date=2013|volume=8|issue=5|article-number=e62111|doi=10.1371/journal.pone.0062111|pmid=23667454|pmc=3648534|bibcode=2013PLoSO...862111K|doi-access=free}}</ref> Ecosystem collapse could be reversible and in this way differs from [[species extinction]].<ref name="Boitani-2014">{{cite journal|last1=Boitani|first1=Luigi|last2=Mace|first2=Georgina M.|last3=Rondinini|first3=Carlo|title=Challenging the Scientific Foundations for an IUCN Red List of Ecosystems|journal=Conservation Letters|doi=10.1111/conl.12111|volume=8|issue=2|date=2014|pages=125–131|url=http://discovery.ucl.ac.uk/1443166/1/conl12111.pdf|hdl=11573/624610|s2cid=62790495|hdl-access=free|access-date=2021-01-06|archive-date=2018-07-22|archive-url=https://web.archive.org/web/20180722080846/http://discovery.ucl.ac.uk/1443166/1/conl12111.pdf|url-status=live}}{{open access}}</ref> Quantitative assessments of the [[IUCN Red List of Ecosystems|risk of collapse]] are used as measures of conservation status and trends.

=== Management ===

@@ Line 24: / Line 24: @@
 Ecosystems are controlled by external and internal [[Environmental factor|factors]]. External factors—including [[climate]]—control the ecosystem's structure, but are not influenced by it. By contrast, internal factors control and are controlled by ecosystem processes; these include [[decomposition]], the types of species present, root competition, shading, disturbance, and succession. While external factors generally determine which [[Resource (biology)|resource]] inputs an ecosystem has, their availability within the ecosystem is controlled by internal factors. Ecosystems are [[wikt:dynamic|dynamic]], subject to periodic disturbances and always in the process of recovering from past disturbances. The tendency of an ecosystem to remain close to its equilibrium state, is termed its [[resistance (ecology)|resistance]]. Its capacity to absorb disturbance and reorganize, while undergoing change so as to retain essentially the same function, structure, identity, is termed its [[ecological resilience]].
-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. [[Biome]]s are general classes or categories of ecosystems. However, there is no clear distinction between biomes and ecosystems. [[Ecological classification|Ecosystem classifications]] are specific kinds of ecological classifications that consider all four elements of the definition of ecosystems: a biotic component, an [[abiotic]] complex, the interactions between and within them, and the physical space they occupy. Biotic factors are living things; such as plants, while abiotic are non-living components; such as soil. Plants allow energy to enter the system through [[photosynthesis]], building up plant tissue. Animals play an important role in the movement of [[matter]] and energy through the system, by feeding on plants and one another. They also influence the quantity of plant and [[Microbe|microbial]] [[Biomass (ecology)|biomass]] present. By breaking down dead [[organic matter]], [[decomposer]]s 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.
+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. [[Biome]]s are general classes or categories of ecosystems. However, there is no clear distinction between biomes and ecosystems. [[Ecological classification|Ecosystem classifications]] are specific kinds of ecological classifications that consider all four elements of the definition of ecosystems: a biotic component, an [[abiotic]] complex, the interactions between and within them, and the physical space they occupy. Biotic factors are living things, such as plants, while abiotic factors are non-living components, such as soil. Plants allow energy to enter the system through [[photosynthesis]], building up plant tissue. Animals play an important role in the movement of [[matter]] and energy through the system, by feeding on plants and one another. They also influence the quantity of plant and [[Microbe|microbial]] [[Biomass (ecology)|biomass]] present. By breaking down dead [[organic matter]], [[decomposer]]s 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.
-Ecosystems provide a variety of goods and services upon which people depend, and may be part of. Ecosystem goods include the "tangible, material products" of ecosystem processes such as water, food, fuel, construction material, and [[medicinal plants]]. [[Ecosystem services]], on the other hand, are generally "improvements in the condition or location of things of value". These include things like the maintenance of [[Water cycle|hydrological cycles]], cleaning air and water, the maintenance of oxygen in the atmosphere, crop [[pollination]] and even things like beauty, inspiration and opportunities for research. Many ecosystems become degraded through human impacts, such as [[Erosion|soil loss]], [[Air pollution|air]] and [[water pollution]], [[habitat fragmentation]], [[Interbasin transfer|water diversion]], [[Wildfire suppression|fire suppression]], and [[introduced species]] and [[invasive species]]. These threats can lead to abrupt transformation of the ecosystem or to gradual disruption of biotic processes and degradation of [[Abiotic component|abiotic]] conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered [[Ecosystem collapse|"collapsed]]". [[Restoration ecology|Ecosystem restoration]] can contribute to achieving the [[Sustainable Development Goals]].
+Ecosystems provide a variety of goods and services upon which people depend, and may be part of. Ecosystem goods include the "tangible, material products" of ecosystem processes such as water, food, fuel, construction material, and [[medicinal plants]]. [[Ecosystem services]], on the other hand, are generally "improvements in the condition or location of things of value". These include maintenance of [[Water cycle|hydrological cycles]], cleaning air and water, the maintenance of oxygen in the atmosphere, crop [[pollination]], and opportunities for research. Many ecosystems become degraded through human impacts, such as [[Erosion|soil loss]], [[Air pollution|air]] and [[water pollution]], [[habitat fragmentation]], [[Interbasin transfer|water diversion]], [[Wildfire suppression|fire suppression]], and [[introduced species]] and [[invasive species]]. These threats can lead to abrupt transformation of the ecosystem or to gradual disruption of biotic processes and degradation of [[Abiotic component|abiotic]] conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered [[Ecosystem collapse|"collapsed]]". [[Restoration ecology|Ecosystem restoration]] can contribute to achieving the [[Sustainable Development Goals]].
 {{TOC limit|3}}
@@ Line 66: / Line 66: @@
 [[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.<ref name="Chapin-2011e" />{{rp|157}} 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 ecosystem]]s, the vast majority of the net primary production ends up being broken down by [[decomposition|decomposers]]. The remainder is consumed by animals while still alive and enters the plant-based trophic system. After plants and animals die, the organic matter contained in them enters the detritus-based trophic system.<ref name="Chapin-2011i">{{Cite book|last=Chapin|first=F. Stuart III|title=Principles of terrestrial ecosystem ecology|date=2011|publisher=Springer|others=P. A. Matson, Peter Morrison Vitousek, Melissa C. Chapin|isbn=978-1-4419-9504-9|edition=2nd|location=New York|chapter=Chapter 10: Trophic Dynamics|oclc=755081405}}</ref>
-[[Ecosystem respiration]] is the sum of [[Cellular respiration|respiration]] by all living organisms (plants, animals, and decomposers) in the ecosystem.<ref>{{Cite journal|last1=Yvon-Durocher|first1=Gabriel|last2=Caffrey|first2=Jane M.|last3=Cescatti|first3=Alessandro|last4=Dossena|first4=Matteo|last5=Giorgio|first5=Paul del|last6=Gasol|first6=Josep M.|last7=Montoya|first7=José M.|last8=Pumpanen|first8=Jukka|last9=Staehr|first9=Peter A.|date=2012|title=Reconciling the temperature dependence of respiration across timescales and ecosystem types|journal=Nature|language=En|volume=487|issue=7408|pages=472–476|bibcode=2012Natur.487..472Y|doi=10.1038/nature11205|issn=0028-0836|pmid=22722862|s2cid=4422427}}</ref> [[Net ecosystem production]] is the difference between [[Primary production|gross primary production]] (GPP) and ecosystem respiration.<ref name="Lovett-2006">{{Cite journal|last1=Lovett|first1=Gary M.|last2=Cole|first2=Jonathan J.|last3=Pace|first3=Michael L.|date=2006|title=Is Net Ecosystem Production Equal to Ecosystem Carbon Accumulation?|journal=Ecosystems|language=en|volume=9|issue=1|pages=152–155|doi=10.1007/s10021-005-0036-3|bibcode=2006Ecosy...9..152L |issn=1435-0629|s2cid=5890190}}</ref> In the absence of disturbance, net ecosystem production is equivalent to the net carbon accumulation in the ecosystem.
+[[Ecosystem respiration]] is the sum of [[Cellular respiration|respiration]] by all living organisms (plants, animals, and decomposers) in the ecosystem.<ref>{{Cite journal|last1=Yvon-Durocher|first1=Gabriel|last2=Caffrey|first2=Jane M.|last3=Cescatti|first3=Alessandro|last4=Dossena|first4=Matteo|last5=Giorgio|first5=Paul del|last6=Gasol|first6=Josep M.|last7=Montoya|first7=José M.|last8=Pumpanen|first8=Jukka|last9=Staehr|first9=Peter A.|date=2012|title=Reconciling the temperature dependence of respiration across timescales and ecosystem types|journal=Nature|language=En|volume=487|issue=7408|pages=472–476|bibcode=2012Natur.487..472Y|doi=10.1038/nature11205|issn=0028-0836|pmid=22722862|s2cid=4422427}}</ref> [[Net ecosystem production]] is the difference between [[Primary production|gross primary production]] (GPP) and ecosystem respiration.<ref name="Lovett-2006">{{Cite journal|last1=Lovett|first1=Gary M.|last2=Cole|first2=Jonathan J.|last3=Pace|first3=Michael L.|date=2006|title=Is Net Ecosystem Production Equal to Ecosystem Carbon Accumulation?|journal=Ecosystems|language=en|volume=9|issue=1|pages=152–155|doi=10.1007/s10021-005-0036-3|bibcode=2006Ecosy...9..152L |issn=1435-0629|s2cid=5890190 |url=https://figshare.com/articles/journal_contribution/24840588 }}</ref> In the absence of disturbance, net ecosystem production is equivalent to the net carbon accumulation in the ecosystem.
 Energy can also be released from an ecosystem through disturbances such as [[wildfire]] or transferred to other ecosystems (e.g., from a forest to a stream to a lake) by [[erosion]].
@@ Line 93: / Line 93: @@
 {{Further|Resistance (ecology)|Ecological resilience}}
-Ecosystems are dynamic entities. They are subject to periodic disturbances and are always in the process of recovering from past disturbances.<ref name="Chapin-2011k" />{{rp|347}} When a [[perturbation (biology)|perturbation]] 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 [[resistance (ecology)|resistance]]. The capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity, and feedbacks is termed its [[ecological resilience]].<ref>{{Cite book|title=Principles of ecosystem stewardship: resilience-based natural resource management in a changing world|date=2009|publisher=Springer|editor-first1=F. Stuart III |editor-last1=Chapin |editor-first2=Gary P. |editor-last2=Kofinas |editor-first3=Carl |editor-last3=Folke |editor-first4=Melissa C. |editor-last4=Chapin|isbn=978-0-387-73033-2|edition=1st|location=New York|oclc=432702920}}</ref><ref>{{Cite journal|last1=Walker|first1=Brian|last2=Holling|first2=C. S.|last3=Carpenter|first3=Stephen R.|last4=Kinzig|first4=Ann P.|date=2004|title=Resilience, Adaptability and Transformability in Social-ecological Systems|url=https://www.ecologyandsociety.org/vol9/iss2/art5/|journal=Ecology and Society|language=en|volume=9|issue=2|pages=art5|doi=10.5751/ES-00650-090205 |doi-access=free |issn=1708-3087|hdl=10535/3282|hdl-access=free|access-date=2021-07-23|archive-date=2019-05-17|archive-url=https://web.archive.org/web/20190517073955/https://www.ecologyandsociety.org/vol9/iss2/art5/|url-status=live}}</ref> Resilience thinking also includes humanity as an integral part of the [[biosphere]] where we are dependent on [[ecosystem services]] for our survival and must build and maintain their natural capacities to withstand shocks and disturbances.<ref>{{Cite web|last=Simonsen|first=S.H. |publisher=Stockholm Resilience Centre |title=Applying Resilience Thinking|url=https://whatisresilience.org/wp-content/uploads/2016/04/Applying_resilience_thinking.pdf|url-status=live|archive-url=https://web.archive.org/web/20171215163627/http://whatisresilience.org:80/wp-content/uploads/2016/04/Applying_resilience_thinking.pdf |archive-date=2017-12-15 }}</ref> Time plays a central role over a wide range, for example, in the slow development of soil from bare rock and the faster [[ecological succession|recovery of a community from disturbance]].<ref name="Chapin-2011e" />{{rp|67}}
+Ecosystems are dynamic entities. They are subject to periodic disturbances and are always in the process of recovering from past disturbances.<ref name="Chapin-2011k" />{{rp|347}} When a [[perturbation (biology)|perturbation]] 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 [[resistance (ecology)|resistance]]. The capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity, and feedbacks is termed its [[ecological resilience]].<ref>{{Cite book|title=Principles of ecosystem stewardship: resilience-based natural resource management in a changing world|date=2009|publisher=Springer|editor-first1=F. Stuart III |editor-last1=Chapin |editor-first2=Gary P. |editor-last2=Kofinas |editor-first3=Carl |editor-last3=Folke |editor-first4=Melissa C. |editor-last4=Chapin|isbn=978-0-387-73033-2|edition=1st|location=New York|oclc=432702920}}</ref><ref>{{Cite journal|last1=Walker|first1=Brian|last2=Holling|first2=C. S.|last3=Carpenter|first3=Stephen R.|last4=Kinzig|first4=Ann P.|date=2004|title=Resilience, Adaptability and Transformability in Social-ecological Systems|url=https://www.ecologyandsociety.org/vol9/iss2/art5/|journal=Ecology and Society|language=en|volume=9|issue=2|pages=art5|doi=10.5751/ES-00650-090205 |bibcode=2004EcSoc...9Tar.5W |doi-access=free |issn=1708-3087|hdl=10535/3282|hdl-access=free|access-date=2021-07-23|archive-date=2019-05-17|archive-url=https://web.archive.org/web/20190517073955/https://www.ecologyandsociety.org/vol9/iss2/art5/|url-status=live}}</ref> Resilience thinking also includes humanity as an integral part of the [[biosphere]] where we are dependent on [[ecosystem services]] for our survival and must build and maintain their natural capacities to withstand shocks and disturbances.<ref>{{Cite web|last=Simonsen|first=S.H. |publisher=Stockholm Resilience Centre |title=Applying Resilience Thinking|url=https://whatisresilience.org/wp-content/uploads/2016/04/Applying_resilience_thinking.pdf|url-status=live|archive-url=https://web.archive.org/web/20171215163627/http://whatisresilience.org:80/wp-content/uploads/2016/04/Applying_resilience_thinking.pdf |archive-date=2017-12-15 }}</ref> Time plays a central role over a wide range, for example, in the slow development of soil from bare rock and the faster [[ecological succession|recovery of a community from disturbance]].<ref name="Chapin-2011e" />{{rp|67}}
 [[Disturbance (ecology)|Disturbance]] also plays an important role in ecological processes. [[F. Stuart Chapin III|F. Stuart Chapin]] and coauthors define disturbance as "a relatively discrete event in time that removes plant biomass".<ref name="Chapin-2011k">{{Cite book|last=Chapin|first=F. Stuart III|title=Principles of terrestrial ecosystem ecology|date=2011|publisher=Springer|others=P. A. Matson, Peter Morrison Vitousek, Melissa C. Chapin|isbn=978-1-4419-9504-9|edition=2nd|location=New York|chapter=Chapter 12: Temporal Dynamics|oclc=755081405}}</ref>{{rp|346}} This can range from [[herbivore]] outbreaks, treefalls, fires, hurricanes, floods, [[Glacial motion|glacial advances]], to [[Types of volcanic eruptions|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 succession, a "directional change in ecosystem structure and functioning resulting from biotically driven changes in resource supply."<ref name="Chapin-2011m">{{Cite book|last=Chapin|first=F. Stuart III|title=Principles of terrestrial ecosystem ecology|date=2011|publisher=Springer|others=P. A. Matson, Peter Morrison Vitousek, Melissa C. Chapin|isbn=978-1-4419-9504-9|edition=2nd|location=New York|chapter=Glossary|oclc=755081405}}</ref>{{rp|470}}
@@ Line 99: / Line 99: @@
 The frequency and severity of disturbance determine the way it affects ecosystem function. A major disturbance like a volcanic eruption or [[Glacier|glacial]] advance and retreat leave behind soils that lack plants, animals or organic matter. Ecosystems that experience such disturbances undergo [[primary succession]]. A less severe disturbance like forest fires, hurricanes or cultivation result in [[secondary succession]] and a faster recovery.<ref name="Chapin-2011k" />{{rp|348}} More severe and more frequent disturbance result in longer recovery times.
-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. Longer-term changes also shape ecosystem processes. For example, the forests of eastern North America still show legacies of [[Agriculture|cultivation]] which ceased in 1850 when large areas were reverted to forests.<ref name="Chapin-2011k" />{{rp|340}} Another example is the [[methane]] production in eastern [[Siberia]]n lakes that is controlled by [[organic matter]] which accumulated during the [[Pleistocene]].<ref>{{Cite journal|last1=Walter|first1=K. M.|last2=Zimov|first2=S. A.|last3=Chanton|first3=J. P.|last4=Verbyla|first4=D.|last5=Chapin|first5=F. S.|date=2006|title=Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming|url=http://faculty.jsd.claremont.edu/emorhardt/159/pdfs/2007/Walter%20et%20al.%202006.pdf |journal=Nature|language=en|volume=443|issue=7107|pages=71–75|doi=10.1038/nature05040|pmid=16957728|bibcode=2006Natur.443...71W|s2cid=4415304 |s2cid-access=free |issn=0028-0836|access-date=2021-08-16|archive-date=Nov 23, 2011 |archive-url=https://web.archive.org/web/20111123193233/http://faculty.jsd.claremont.edu/emorhardt/159/pdfs/2007/Walter%20et%20al.%202006.pdf |url-status=dead }}</ref>
+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. Longer-term changes also shape ecosystem processes. For example, the forests of eastern North America still show legacies of [[Agriculture|cultivation]] which ceased in 1850 when large areas were reverted to forests.<ref name="Chapin-2011k" />{{rp|340}} Another example is the [[methane]] production in eastern [[Siberia]]n lakes that is controlled by [[organic matter]] which accumulated during the [[Pleistocene]].<ref>{{Cite journal|last1=Walter|first1=K. M.|last2=Zimov|first2=S. A.|last3=Chanton|first3=J. P.|last4=Verbyla|first4=D.|last5=Chapin|first5=F. S.|date=2006|title=Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming|url=http://faculty.jsd.claremont.edu/emorhardt/159/pdfs/2007/Walter%20et%20al.%202006.pdf |journal=Nature|language=en|volume=443|issue=7107|pages=71–75|doi=10.1038/nature05040|pmid=16957728|bibcode=2006Natur.443...71W|s2cid=4415304 |s2cid-access=free |issn=0028-0836|access-date=2021-08-16|archive-date=Nov 23, 2011 |archive-url=https://web.archive.org/web/20111123193233/http://faculty.jsd.claremont.edu/emorhardt/159/pdfs/2007/Walter%20et%20al.%202006.pdf }}</ref>
 {{clear}}
@@ Line 115: / Line 115: @@
 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 [[ammonification|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.<ref name="Chapin-2011h" />{{rp|277}} Under nitrogen-rich and oxygen-poor conditions, nitrates and nitrites are converted to [[nitrogen|nitrogen gas]], a process known as [[denitrification]].<ref name="Chapin-2011h" />{{rp|281}}
-Mycorrhizal fungi which are symbiotic with plant roots, use carbohydrates supplied by the plants and in return transfer phosphorus and nitrogen compounds back to the plant roots.<ref>{{Cite journal|last=Bolan|first=N.S.|date=1991|title=A critical review on the role of mycorrhizal fungi in the uptake of phosphorus by plants|journal=Plant and Soil|volume=134|issue=2|pages=189–207|doi=10.1007/BF00012037|bibcode=1991PlSoi.134..189B |s2cid=44215263}}</ref><ref name="Hestrin-2019" /> This is an important pathway of organic nitrogen transfer from dead organic matter to plants. This mechanism may contribute to more than 70 Tg of annually assimilated plant nitrogen, thereby playing a critical role in global nutrient cycling and ecosystem function.<ref name="Hestrin-2019">{{Cite journal|last1=Hestrin|first1=R.|last2=Hammer|first2=E.C.|last3=Mueller|first3=C.W.|date=2019|title=Synergies between mycorrhizal fungi and soil microbial communities increase plant nitrogen acquisition|journal=Commun Biol|volume=2|page=233|doi=10.1038/s42003-019-0481-8|pmid=31263777|pmc=6588552}}</ref>
+Mycorrhizal fungi which are symbiotic with plant roots, use carbohydrates supplied by the plants and in return transfer phosphorus and nitrogen compounds back to the plant roots.<ref>{{Cite journal|last=Bolan|first=N.S.|date=1991|title=A critical review on the role of mycorrhizal fungi in the uptake of phosphorus by plants|journal=Plant and Soil|volume=134|issue=2|pages=189–207|doi=10.1007/BF00012037|bibcode=1991PlSoi.134..189B |s2cid=44215263}}</ref><ref name="Hestrin-2019" /> This is an important pathway of organic nitrogen transfer from dead organic matter to plants. This mechanism may contribute to more than 70 Tg of annually assimilated plant nitrogen, thereby playing a critical role in global nutrient cycling and ecosystem function.<ref name="Hestrin-2019">{{Cite journal|last1=Hestrin|first1=R.|last2=Hammer|first2=E.C.|last3=Mueller|first3=C.W.|date=2019|title=Synergies between mycorrhizal fungi and soil microbial communities increase plant nitrogen acquisition|journal=Commun Biol|volume=2|issue=1 |article-number=233|doi=10.1038/s42003-019-0481-8|pmid=31263777|pmc=6588552 |bibcode=2019CmBio...2..233H }}</ref>
 Phosphorus enters ecosystems through [[weathering]]. As ecosystems age this supply diminishes, making phosphorus-limitation more common in older landscapes (especially in the tropics).<ref name="Chapin-2011h" />{{rp|287–290}} 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.<ref name="Chapin-2011h" />{{rp|291}}
@@ Line 173: / Line 173: @@
 Many ecosystems become degraded through human impacts, such as [[Erosion|soil loss]], [[Air pollution|air]] and [[water pollution]], [[habitat fragmentation]], [[Interbasin transfer|water diversion]], [[Wildfire suppression|fire suppression]], and [[introduced species]] and [[invasive species]].<ref name="Chapin-2011l" />{{rp|437}}
-These threats can lead to abrupt transformation of the ecosystem or to gradual disruption of biotic processes and degradation of [[Abiotic component|abiotic]] conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered ''[[ecosystem collapse|collapsed]]'' (see also [[IUCN Red List of Ecosystems]]).<ref name="Keith-2013">{{cite journal|last1=Keith|first1=DA|last2=Rodríguez|first2=J.P.|last3=Rodríguez-Clark|first3=K.M.|last4=Aapala|first4=K.|last5=Alonso|first5=A.|last6=Asmussen|first6=M.|last7=Bachman|first7=S.|last8=Bassett|first8=A.|last9=Barrow|first9=E.G.|last10=Benson|first10=J.S.|last11=Bishop|first11=M.J.|last12=Bonifacio|first12=R.|last13=Brooks|first13=T.M.|last14=Burgman|first14=M.A.|last15=Comer|first15=P.|last16=Comín|first16=F.A.|last17=Essl|first17=F.|last18=Faber-Langendoen|first18=D.|last19=Fairweather|first19=P.G.|last20=Holdaway|first20=R.J.|last21=Jennings|first21=M.|last22=Kingsford|first22=R.T.|last23=Lester|first23=R.E.|last24=Mac Nally|first24=R.|last25=McCarthy|first25=M.A.|last26=Moat|first26=J.|last27=Nicholson|first27=E.|last28=Oliveira-Miranda|first28=M.A.|last29=Pisanu|first29=P.|last30=Poulin|first30=B.|last31=Riecken|first31=U.|last32=Spalding|first32=M.D.|last33=Zambrano-Martínez|first33=S.|title=Scientific Foundations for an IUCN Red List of Ecosystems|journal=PLOS ONE|date=2013|volume=8|issue=5|page=e62111|doi=10.1371/journal.pone.0062111|pmid=23667454|pmc=3648534|bibcode=2013PLoSO...862111K|doi-access=free}}</ref> Ecosystem collapse could be reversible and in this way differs from [[species extinction]].<ref name="Boitani-2014">{{cite journal|last1=Boitani|first1=Luigi|last2=Mace|first2=Georgina M.|last3=Rondinini|first3=Carlo|title=Challenging the Scientific Foundations for an IUCN Red List of Ecosystems|journal=Conservation Letters|doi=10.1111/conl.12111|volume=8|issue=2|date=2014|pages=125–131|url=http://discovery.ucl.ac.uk/1443166/1/conl12111.pdf|hdl=11573/624610|s2cid=62790495|hdl-access=free|access-date=2021-01-06|archive-date=2018-07-22|archive-url=https://web.archive.org/web/20180722080846/http://discovery.ucl.ac.uk/1443166/1/conl12111.pdf|url-status=live}}{{open access}}</ref> Quantitative assessments of the [[IUCN Red List of Ecosystems|risk of collapse]] are used as measures of conservation status and trends.
+These threats can lead to abrupt transformation of the ecosystem or to gradual disruption of biotic processes and degradation of [[Abiotic component|abiotic]] conditions of the ecosystem. Once the original ecosystem has lost its defining features, it is considered ''[[ecosystem collapse|collapsed]]'' (see also [[IUCN Red List of Ecosystems]]).<ref name="Keith-2013">{{cite journal|last1=Keith|first1=DA|last2=Rodríguez|first2=J.P.|last3=Rodríguez-Clark|first3=K.M.|last4=Aapala|first4=K.|last5=Alonso|first5=A.|last6=Asmussen|first6=M.|last7=Bachman|first7=S.|last8=Bassett|first8=A.|last9=Barrow|first9=E.G.|last10=Benson|first10=J.S.|last11=Bishop|first11=M.J.|last12=Bonifacio|first12=R.|last13=Brooks|first13=T.M.|last14=Burgman|first14=M.A.|last15=Comer|first15=P.|last16=Comín|first16=F.A.|last17=Essl|first17=F.|last18=Faber-Langendoen|first18=D.|last19=Fairweather|first19=P.G.|last20=Holdaway|first20=R.J.|last21=Jennings|first21=M.|last22=Kingsford|first22=R.T.|last23=Lester|first23=R.E.|last24=Mac Nally|first24=R.|last25=McCarthy|first25=M.A.|last26=Moat|first26=J.|last27=Nicholson|first27=E.|last28=Oliveira-Miranda|first28=M.A.|last29=Pisanu|first29=P.|last30=Poulin|first30=B.|last31=Riecken|first31=U.|last32=Spalding|first32=M.D.|last33=Zambrano-Martínez|first33=S.|title=Scientific Foundations for an IUCN Red List of Ecosystems|journal=PLOS ONE|date=2013|volume=8|issue=5|article-number=e62111|doi=10.1371/journal.pone.0062111|pmid=23667454|pmc=3648534|bibcode=2013PLoSO...862111K|doi-access=free}}</ref> Ecosystem collapse could be reversible and in this way differs from [[species extinction]].<ref name="Boitani-2014">{{cite journal|last1=Boitani|first1=Luigi|last2=Mace|first2=Georgina M.|last3=Rondinini|first3=Carlo|title=Challenging the Scientific Foundations for an IUCN Red List of Ecosystems|journal=Conservation Letters|doi=10.1111/conl.12111|volume=8|issue=2|date=2014|pages=125–131|url=http://discovery.ucl.ac.uk/1443166/1/conl12111.pdf|hdl=11573/624610|s2cid=62790495|hdl-access=free|access-date=2021-01-06|archive-date=2018-07-22|archive-url=https://web.archive.org/web/20180722080846/http://discovery.ucl.ac.uk/1443166/1/conl12111.pdf|url-status=live}}{{open access}}</ref> Quantitative assessments of the [[IUCN Red List of Ecosystems|risk of collapse]] are used as measures of conservation status and trends.
 === Management ===

Ecosystem: Difference between revisions

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