Editing Ecosystem (section)

=== External and internal factors ===
Ecosystems are controlled by both external and internal factors. External factors, also called state factors, control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. On broad geographic scales, [[climate]] is the factor that "most strongly determines ecosystem processes and structure".<ref name="Chapin-2011a">{{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 1: The Ecosystem Concept|oclc=755081405}}</ref>{{rp|14}} Climate determines the [[biome]] in which the ecosystem is embedded. Rainfall patterns and seasonal temperatures influence photosynthesis and thereby determine the amount of energy available to the ecosystem.<ref name="Chapin-2011d" />{{rp|145}}

[[Parent material]] determines the nature of the soil in an ecosystem, 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. For example, ecosystems can be quite different if situated in a small depression on the landscape, versus one present on an adjacent steep hillside.<ref name="Chapin-2011b">{{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 2: Earth's Climate System|oclc=755081405}}</ref>{{rp|39}}<ref name="Chapin-2011c">{{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 3: Geology, Soils, and Sediments|oclc=755081405}}</ref>{{rp|66}}

Other external factors that play an important role in ecosystem functioning include time and potential [[biota (ecology)|biota]], the organisms that are present in a region and could potentially occupy a particular site. 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.<ref name="Chapin-2011j">{{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 11: Species Effects on Ecosystem Processes|oclc=755081405}}</ref>{{rp|321}} The [[introduced species|introduction of non-native species]] can cause substantial shifts in ecosystem function.<ref>{{Cite journal|last1=Simberloff|first1=Daniel|last2=Martin|first2=Jean-Louis|last3=Genovesi|first3=Piero|last4=Maris|first4=Virginie|last5=Wardle|first5=David A.|last6=Aronson|first6=James|last7=Courchamp|first7=Franck|last8=Galil|first8=Bella|last9=García-Berthou|first9=Emili|date=2013|title=Impacts of biological invasions: what's what and the way forward|journal=Trends in Ecology & Evolution|volume=28|issue=1|pages=58–66|doi=10.1016/j.tree.2012.07.013|pmid=22889499|bibcode=2013TEcoE..28...58S |issn=0169-5347|hdl=10261/67376|hdl-access=free}}</ref>

Unlike external factors, internal factors in ecosystems not only control ecosystem processes but are also controlled by them.<ref name="Chapin-2011a" />{{rp|16}} While the [[Resource (biology)|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.<ref>{{Cite web|date=2018-07-17|title=46.1A: Ecosystem Dynamics|url=https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundless)/46%3A_Ecosystems/46.1%3A__Ecology_of_Ecosystems/46.1A%3A_Ecosystem_Dynamics|access-date=2021-08-02|website=Biology LibreTexts|language=en|archive-date=2021-08-02|archive-url=https://web.archive.org/web/20210802144400/https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book:_General_Biology_(Boundless)/46:_Ecosystems/46.1:__Ecology_of_Ecosystems/46.1A:_Ecosystem_Dynamics|url-status=live}}{{open access}}[[File:CC-BY icon.svg|50px]] Text was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/  Creative Commons Attribution 4.0 International License] {{Webarchive|url=https://web.archive.org/web/20171016050101/https://creativecommons.org/licenses/by/4.0/ |date=2017-10-16 }}.</ref> Other factors like disturbance, succession or the types of species present are also internal factors.