Species richness is the number of different species represented in an ecological community, landscape or region.[1]Species richness is simply a count of species, and it does not take into account the abundances of the species or their relative abundance distributions. Species richness is sometimes considered synonymous with species diversity, but the formal metric species diversity takes into account both species richness and species evenness.
Global mammal richness (2015)Global amphibian richness (2015)
Depending on the purposes of quantifying species richness, the individuals can be selected in different ways. They can be, for example, trees found in an inventory plot, birds observed from a monitoring point, or beetles collected in a pitfall trap. Once the set of individuals has been defined, its species richness can be exactly quantified, provided the species-level taxonomy of the organisms of interest is well enough known. Applying different species delimitations will lead to different species richness values for the same set of individuals.
In practice, people are usually interested in the species richness of areas so large that not all individuals in them can be observed and identified to species. Then applying different sampling methods will lead to different sets of individuals being observed for the same area of interest, and the species richness of each set may be different. When a new individual is added to a set, it may introduce a species that was not yet represented in the set, and thereby increase the species richness of the set. For this reason, sets with many individuals can be expected to contain more species than sets with fewer individuals.
If species richness of the obtained sample is taken to represent species richness of the underlying habitat or other larger unit, values are only comparable if sampling efforts are standardised in an appropriate way. Resampling methods can be used to bring samples of different sizes to a common footing.[2] Properties of the sample, especially the number of species only represented by one or a few individuals, can be used to help estimating the species richness in the population from which the sample was drawn.[3][4][5]
Trends in species richnessedit
The observed species richness is affected not only by the number of individuals but also by the heterogeneity of the sample. If individuals are drawn from different environmental conditions (or different habitats), the species richness of the resulting set can be expected to be higher than if all individuals are drawn from similar environments. The accumulation of new species with increasing sampling effort can be visualised with a species accumulation curve. Such curves can be constructed in different ways.[6] Increasing the area sampled increases observed species richness both because more individuals get included in the sample and because large areas are environmentally more heterogeneous than small areas.
Many organism groups have most species in the tropics, which leads to latitudinal gradients in species richness. There has been much discussion about the relationship between productivity and species richness. Results have varied among studies, such that no global consensus on either the pattern or its possible causes has emerged.[7]
Applicationsedit
Species richness is often used as a criterion when assessing the relative conservation values of habitats or landscapes. However, species richness is blind to the identity of the species. An area with many endemic or rare species is generally considered to have higher conservation value than another area where species richness is similar, but all the species are common and widespread.
^Colwell, Robert K. (2009). "Biodiversity: Concepts, Patterns and Measurement". In Simon A. Levin (ed.). The Princeton Guide to Ecology. Princeton: Princeton University Press. pp. 257–263.
^Colwell, R. K. and Coddington, J. A. (1994) Estimating terrestrial biodiversity through extrapolation. Philosophical Transactions: Biological Sciences, 345, 101–118.
^Chao, A. (1984) Non-parametric estimation of the number of classes in a population. Scandinavian Journal of Statistics, 11, 265–270.
^Chao, A. (2005) Species richness estimation. Pages 7909–7916 in N. Balakrishnan, C. B. Read, and B. Vidakovic, eds. Encyclopedia of Statistical Sciences. New York, Wiley.
^Webb, L. J.; Tracey, J. G.; Williams, W. T.; Lance, G. N. (1969), Studies in the Numerical Analysis of Complex Rain-Forest Communities: II. The Problem of Species-Sampling. Journal of Ecology, Vol. 55, No. 2, Jul., 1967, pp. 525-538, Journal of Ecology, British Ecological Society, JSTOR 2257891
^Scheiner, Samuel M. (October 17, 2003). "Six types of species-area curves". Global Ecology and Biogeography. Wiley. 12 (6): 441–447. Bibcode:2003GloEB..12..441S. doi:10.1046/j.1466-822x.2003.00061.x. ISSN 1466-822X.
^Waide, R. B. et al (1999) The relationship between productivity and species richness. Annual Review of Ecology and Systematics, 30, 257–300.
Kevin J. Gaston & John I. Spicer. 2004. Biodiversity: an introduction, Blackwell Publishing. 2nd Ed., ISBN1-4051-1857-1(pbk.)
Diaz, et al. Ecosystems and Human Well-being: Current State and Trends, Volume 1. Millennium Ecosystem Assessment. 2005. Island Press.
February 16, 2024
species, richness, number, different, species, represented, ecological, community, landscape, region, simply, count, species, does, take, into, account, abundances, species, their, relative, abundance, distributions, sometimes, considered, synonymous, with, sp. Species richness is the number of different species represented in an ecological community landscape or region 1 Species richness is simply a count of species and it does not take into account the abundances of the species or their relative abundance distributions Species richness is sometimes considered synonymous with species diversity but the formal metric species diversity takes into account both species richness and species evenness Global mammal richness 2015 Global amphibian richness 2015 Contents 1 Sampling considerations 2 Trends in species richness 3 Applications 4 See also 5 References 6 Further readingSampling considerations editDepending on the purposes of quantifying species richness the individuals can be selected in different ways They can be for example trees found in an inventory plot birds observed from a monitoring point or beetles collected in a pitfall trap Once the set of individuals has been defined its species richness can be exactly quantified provided the species level taxonomy of the organisms of interest is well enough known Applying different species delimitations will lead to different species richness values for the same set of individuals In practice people are usually interested in the species richness of areas so large that not all individuals in them can be observed and identified to species Then applying different sampling methods will lead to different sets of individuals being observed for the same area of interest and the species richness of each set may be different When a new individual is added to a set it may introduce a species that was not yet represented in the set and thereby increase the species richness of the set For this reason sets with many individuals can be expected to contain more species than sets with fewer individuals If species richness of the obtained sample is taken to represent species richness of the underlying habitat or other larger unit values are only comparable if sampling efforts are standardised in an appropriate way Resampling methods can be used to bring samples of different sizes to a common footing 2 Properties of the sample especially the number of species only represented by one or a few individuals can be used to help estimating the species richness in the population from which the sample was drawn 3 4 5 Trends in species richness editThe observed species richness is affected not only by the number of individuals but also by the heterogeneity of the sample If individuals are drawn from different environmental conditions or different habitats the species richness of the resulting set can be expected to be higher than if all individuals are drawn from similar environments The accumulation of new species with increasing sampling effort can be visualised with a species accumulation curve Such curves can be constructed in different ways 6 Increasing the area sampled increases observed species richness both because more individuals get included in the sample and because large areas are environmentally more heterogeneous than small areas Many organism groups have most species in the tropics which leads to latitudinal gradients in species richness There has been much discussion about the relationship between productivity and species richness Results have varied among studies such that no global consensus on either the pattern or its possible causes has emerged 7 Applications editSpecies richness is often used as a criterion when assessing the relative conservation values of habitats or landscapes However species richness is blind to the identity of the species An area with many endemic or rare species is generally considered to have higher conservation value than another area where species richness is similar but all the species are common and widespread See also editRapoport s rule Scaling pattern of occupancy Species area curve Species discovery curve Storage effectReferences edit Colwell Robert K 2009 Biodiversity Concepts Patterns and Measurement In Simon A Levin ed The Princeton Guide to Ecology Princeton Princeton University Press pp 257 263 Colwell R K and Coddington J A 1994 Estimating terrestrial biodiversity through extrapolation Philosophical Transactions Biological Sciences 345 101 118 Chao A 1984 Non parametric estimation of the number of classes in a population Scandinavian Journal of Statistics 11 265 270 Chao A 2005 Species richness estimation Pages 7909 7916 in N Balakrishnan C B Read and B Vidakovic eds Encyclopedia of Statistical Sciences New York Wiley Webb L J Tracey J G Williams W T Lance G N 1969 Studies in the Numerical Analysis of Complex Rain Forest Communities II The Problem of Species Sampling Journal of Ecology Vol 55 No 2 Jul 1967 pp 525 538 Journal of Ecology British Ecological Society JSTOR 2257891 Scheiner Samuel M October 17 2003 Six types of species area curves Global Ecology and Biogeography Wiley 12 6 441 447 Bibcode 2003GloEB 12 441S doi 10 1046 j 1466 822x 2003 00061 x ISSN 1466 822X Waide R B et al 1999 The relationship between productivity and species richness Annual Review of Ecology and Systematics 30 257 300 Further reading edit nbsp Scholia has a profile for species richness Q17146659 Kevin J Gaston amp John I Spicer 2004 Biodiversity an introduction Blackwell Publishing 2nd Ed ISBN 1 4051 1857 1 pbk Diaz et al Ecosystems and Human Well being Current State and Trends Volume 1 Millennium Ecosystem Assessment 2005 Island Press Retrieved from https en wikipedia org w index php title Species richness amp oldid 1188949367, wikipedia, wiki, book, books, library,
