View source for Biodiversity, ecosystem functioning and ecosystem function

It is generally assumed that biodiversity is essential for ecosystem function - the goods and services that ecosystems provide to humanity. Diversity of species and size of populations - the narrow definition of biodiversity - indirectly play a role. In fact, most goods and services arise through ecosystem functioning, the broader scope of biodiversity which encompasses the interplay of species and their interaction with the environment. Much research is focusing in recent decades on unraveling the relationship between biodiversity, ecosystem functioning and ecosystem function.

Many ecosystems around the world are currently undergoing profound changes in species composition due to the influence of human activity and climate change. These changes are likely to affect the services that ecosystems provide to humanity. Questions about the relationships between biodiversity, ecosystem functioning and ecosystem function have therefore become urgent.<ref>Walker, B.H., 1992. Biodiversity and ecological redundancy. Conserv. Biol. 6: 18-23.</ref><ref>Schulze, E.-D. and Mooney, H. A. (eds). 1993. Biodiversity and ecosystem function. Springer Verlag</ref><ref>Jones, C. G., and Lawton, J. H. editors. 1995. Linking species and ecosystems. Chapman and Hall, New York, New York, USA</ref><ref>Johnson, K.H., Vogt, K.A., Clark, H., Schmitz, O. and Vogt, D. 1996.  Biodiversity and the productivity and stability of ecosystems. Trends in Ecology & Evolution 11: 372-377</ref> 


{{ Definition| title = Ecosystem function
| definition = The capacity of natural processes and components to provide goods and services that satisfy human needs, either directly or indirectly<ref>de Groot, R.S., Wilson, M.A. and Boumans, R.M.J. 2002. A typology for the classification, description and valuation of ecosystem functions, goods and services. Ecological Economics 41: 393–408</ref>. 
}}

{{ Definition| title = Ecosystem functioning
| definition = Ecosystem functioning describes the combined effects of all natural processes that sustain an ecosystem, i.e. the combined effects of individual functions, with the overall rate of functioning being governed by the interplay of abiotic (physical and chemical) and/or biotic factors<ref>Reiss, J., Bridle, J.R., Montoya, J.M. and   Woodward, G. 2009. Emerging horizons in biodiversity and ecosystem functioning research. Trends Ecol. Evol., 24: 505-514</ref>.}}




==Ecosystem function, functioning and biodiversity==
Marine ecosystems provide many important functions at a global, national, regional and individual level. The goods and services provided to society include moderation of climate, processing of waste and toxicants, protection of the coastline, provision of vital food and medicines and a source of employment. Our coasts provide space to live and directly and indirectly create wealth, including millions of jobs in industries such as fishing, aquaculture and tourism. See also the article [[Ecosystem services]].

Although a distinction is not always made, ''ecosystem function'' should be distinguished from ''ecosystem functioning''. Ecosystem functioning  refers to  ecological processes  and  the  causal  relations  that  give  rise  to  them,  to the role of organisms within an ecological system, and to the overall processes  that  sustain  an  ecological  system<ref>Naeem, S. 1998. Species redundancy and ecosystem reliability. Conserv. Biol., 12: 39-45</ref>. It reflects the collective life activities of plants, animals, and microbes and the effects these activities - feeding, growing, moving, excreting waste, etc. - have on the physical and chemical conditions of their environment<ref>Naeem, S., Chapin III, F.S. Costanza, R., Ehrlich, P.R., Golley, F.B., Hooper, D.U., Lawton, J.H., O'Neill, R.V., Mooney, H.A., Sala, O.E., Symstad, A.J. and Tilman, D. 1999. Biodiversity and Ecosystem Functioning: Maintaining Natural Life Support Processes. Issues in Ecology 4. Published by the Ecological Society of America</ref>. Ecosystem function refers to the resulting benefits for  humans  or  other  organisms<ref>Bellwood, D.R., Streit, R.P., Brandl, S.J. and Tebbett, S.B. 2019. The meaning of the term ‘function’ in ecology: A coral reef perspective. Functional Ecology 33: 948–961</ref>. Ecosystem function and ecosystem functioning are complementary<ref>Jax, K. 2005. Function and functioning in ecology: what does it mean? Oikos 3: 641-648</ref>.

There is broad consensus among scientists that ecosystem function is linked to biodiversity. Loss of biodiversity results in degradation of ecosystem functioning and loss of ecosystem functions. This is thought to be because diverse communities contain a greater range of functional traits and are therefore better adapted to naturally available resources. High diversity therefore provides opportunities for more efficient use of resources and ensures stability of ecosystem functions in variable or disturbed environments<ref>Chapin, F.S., Walker, B.H., Hobbs, R.J., Hooper, D.U., Lawton, J.H., Sala, O.E. and Tilman D. 1997. Biotic control over the functioning of ecosystems. Science, 277(5325): 500-504</ref>. In contrast, systems with species-poor communities are less resistant (less capacity to withstand change) and less resilient (less capacity to recover from disturbance) than systems with species-rich communities<ref>Strong, J.A., Andonegi, E., Bizsel. K.C., Danovaro, R., Elliott, M., Franco, A., Garces, E., Little, S.,. Mazik, K., Moncheva, S., Papadopoulou, N., Patrício, J., Queiros, A.M., Smith, C., Stefanova, K. and Solaun, O. 2015. Marine biodiversity and ecosystem function relationships: The potential for practical monitoring applications. Estuarine, Coastal and Shelf Science 161: 46-64</ref>. Biodiversity and ecosystem function are central to both community and ecosystems ecology and need to be understood to predict how communities and ecosystems respond to environmental change and how declining diversity influences ecosystem services on which humans depend<ref name=Duf>Duffy, J.E. 2003. Biodiversity loss, trophic skew and ecosystem functioning. Ecol. Lett. 6: 680–687</ref>. However, the relationship between structural and functional aspects of biodiversity is complex and not yet fully clarified, see the article [[Resilience and resistance]].

The article [[A review of biodiversity-ecosystem function research]] presents an overview of different types of experiments designed to provide insight into the biodiversity-ecosystem function relationship in the marine environment. 

==Empirical theories==
Current understanding of the biodiversity-ecosystem function relationship is largely based on empirical rules derived from analysis of the observed behavior of natural ecosystems when disturbed or under stress. Some rules that are supported by various studies are listed below. <ref>Grime, J.P.,1973. Competitive exclusion in herbaceous vegetation. Nature 242, 344–347</ref><ref>Naeem, S., Thompson, L.J., Lawler, S.P., Lawton, J.H. and Woodfin, R.M. 1994. Declining biodiversity can alter the performance of ecosystems. Nature 368: 734–737</ref><ref>Loreau, M., Naeem, S., Inchausti, P., Bengtsson, J., Grime, J.P., Hector, A., Hooper, D.U., Huston, M.A., Raffaelli, D., Schmid, B., Tilman, D., Wardle, D.A., 2001. Biodiversity and ecosystem functioning: current knowledge and future challenges. Science 294: 804–808</ref><ref>Tilman, D., Isbell, F., Cowles, J.M., 2014. Biodiversity and ecosystem function. Annu. Rev. Ecol. Evol. Syst. 45: 471–493</ref><ref>Eisenhauer, N., Schielzeth, H., Barnes, A.D., Barry, K., Bonn, A., Brose, U., Bruelheide, H., Buchmann, N., Buscot, F., Ebeling, A., Ferlian, O., Freschet, G.T., Giling, D.P., Hättenschwiler, S., Hillebrand, H., Hines, J., Isbell, F., Koller-France, E., König-Ries, B., de Kroon, H., Meyer, S.T., Milcu, A., Müller, J., Nock, C.A., Petermann, J.S., Roscher, C., Scherber, C., Scherer-Lorenzen, M., Schmid, B., Schnitzer, S.A., Schuldt, A., Tscharntke, T., Türke, M., van Dam, N.M., van der Plas, F., Vogel, A., Wagg, C., Wardle, D.A., Weigelt, A., Weisser, W.W., Wirth, C. and Jochum, M. 2019. A multitrophic perspective on biodiversity-ecosystem functioning research. Adv Ecol Res. 19: 1-54</ref><ref>Ali, A. 2023. Biodiversity–ecosystem functioning research: Brief history, major trends and perspectives. Biological Conservation 285, 110210</ref>
*Functional diversity is a more important ecosystem property for the provision of ecosystem services than species richness or the distribution of species abundances. 
*Across ecosystems, there is empirical evidence that the diversity at high trophic levels is most important for providing multiple ecosystem functions and services.
*The efficiency of resource utilization is highest in functionally-diverse ecosystems. This so-called niche complementarity theory postulates that coexisting species with a great variety of functional traits have different requirements for ecological niches which lead to more efficient utilization of available resources through niche differentiation and facilitation.
*Positive biodiversity-ecosystem function relationships have been shown to be strongest in complex resource environments. Environmental heterogeneity promotes complementarity effects, suggesting that habitat homogenization may compromise positive biodiversity effects on ecosystem function.
*Species-rich ecosystems are more likely to include and become dominated by some highly productive species. This is called the selection probability hypothesis.
*Stable and productive ecosystems are typically not pruned to the most productive and competitive species, but also comprise less productive and competitive species with similar functionality. This redundancy implies that one species can (partially) replace another. The loss of one species can be offset by some other species. 
*Many ecosystems are ruled by a small number of key species (also called keystone species or ecosystem engineers). The loss or gain of key species has a significant impact on the ecosystem function.
*Competitive exclusion, where a strong competitor eliminates all weaker competitors with same functionality, is rare. Competitive exclusion leads to a decline in species diversity under conditions of low stress or low disturbance.
*The impact of the loss or gain of a species on ecosystem function is context dependent and often idiosyncratic and unpredictable. What happens, will depend on the local conditions under which the species extinction or addition occurs.

The general validity of these empirical rules is still a subject of research.


==Related articles==
:[[A review of biodiversity-ecosystem function research]]
:[[Measurements of biodiversity]]
:[[Biological Trait Analysis]]
:[[Biodiversity]]
:[[Resilience and resistance]]
:[[Ecosystem services]]


== References ==
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|AuthorFullName1=Job Dronkers
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|AuthorFullName2=Vassiliki, Markantonatou
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[[Category:Marine Biodiversity‏‎]]
[[Category:Coastal and marine ecosystems]]