Species richness

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. Species richness has proven to be a positive representation to show how species interaction in ecosystems can lead to the productivity and growth of biodiversity. ^[2]

Sampling considerations

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 standardized in an appropriate way. Resampling methods can be used to bring samples of different sizes to a common footing.^[3] 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.^[4]^[5]^[6] These indications and adaptations to the detail of population enhancements can provide further diversity in urban ecological areas by means of promoting species richness while also considering the ecological community.

Trends in species richness

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 visualized with a species accumulation curve. Such curves can be constructed in different ways.^[7] 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.^[8] Species diversity and richness is likely to occur in areas of warmer climates because of variability in food types, mating opportunities, urban area provision of cleaner environments and other factors that can lead to an improved species richness.^[9]

Species richness also depicts immense extension by means of expanding in terms of ecological and environmental availability of urban food types which enriches the likelihood of species richness increasing even in urban areas; additionally, increasing food availability in certain environments will provide better chances of species richness in terms of diversity. ^[10] Where there is food, there are animals according to the balance of nature or the ecological balance as it is generally known, ^[11] which expresses types of food chain and food webs which are both used in urban ecology to show the differences but mostly similarities in which feeding relations between species can be understood.^[12] Every type of species will consist of their individual type of feeding relationship with organisms provided by the environment,^[13] however, it is necessary to understand that feeding relationships and the urban species will indeed form a type of symbiotic relationship within an ecosystem according to urban necessities as shown in the image provided.^[14]

Applications

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.

Location-wise, urban settings can influence species richness by means of proper environmental conservation, availability of safety and other factors like water, trees, and sustainable habitat. Species thrives in areas where they are provided with the basic necessities for their survival, even in urban areas where they may face challenges like competition or predators, they still have a high chance of surviving when placed in an environment that provides adequate resources that can benefit the species and promote species diversity and richness.^[15]

References

^ 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.
^ Hordijk, Iris; Maynard, Daniel S.; Hart, Simon P.; Lidong, Mo; ter Steege, Hans; Liang, Jingjing; de-Miguel, Sergio; Nabuurs, Gert-Jan; Reich, Peter B.; Abegg, Meinrad; Adou Yao, C. Yves; Alberti, Giorgio; Almeyda Zambrano, Angelica M.; Alvarado, Braulio V.; Esteban, Alvarez-Davila (June 2023). "Evenness mediates the global relationship between forest productivity and richness". Journal of Ecology. 111 (6): 1308–1326. Bibcode:2023JEcol.111.1308H. doi:10.1111/1365-2745.14098. ISSN 0022-0477.
^ 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. 12 (6). Wiley: 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.
^ Brown, James H. (January 2014). Svenning, Jens‐Christian (ed.). "Why are there so many species in the tropics?". Journal of Biogeography. 41 (1): 8–22. doi:10.1111/jbi.12228. ISSN 0305-0270.
^ Paker, Yair; Yom-Tov, Yoram; Alon-Mozes, Tal; Barnea, Anat (2014-02-01). "The effect of plant richness and urban garden structure on bird species richness, diversity and community structure". Landscape and Urban Planning. 122: 186–195. doi:10.1016/j.landurbplan.2013.10.005. ISSN 0169-2046.
^ "Ecological Balance". wwf.panda.org. Retrieved 2024-10-25.
^ "Food web | Definition, Ecosystem, Food Chain, & Examples | Britannica". www.britannica.com. 2024-08-28. Retrieved 2024-10-25.
^ "Feeding relationships". the science sauce. Retrieved 2024-10-25.
^ "Symbiosis: The Art of Living Together". education.nationalgeographic.org. Retrieved 2024-10-25.
^ "Urban ecosystem | Human Impact, Biodiversity & Pollution | Britannica". www.britannica.com. Retrieved 2024-10-25.

v t e Ecology: Modelling ecosystems: Trophic components
General	Abiotic component Abiotic stress Behaviour Biogeochemical cycle Biomass Biotic component Biotic stress Carrying capacity Competition Ecosystem Ecosystem ecology Ecosystem model Green world hypothesis Keystone species List of feeding behaviours Metabolic theory of ecology Productivity Resource Restoration
Producers	Autotrophs Chemosynthesis Chemotrophs Foundation species Kinetotrophs Mixotrophs Myco-heterotrophy Mycotroph Organotrophs Photoheterotrophs Photosynthesis Photosynthetic efficiency Phototrophs Primary nutritional groups Primary production
Consumers	Apex predator Bacterivore Carnivores Chemoorganotroph Foraging Generalist and specialist species Intraguild predation Herbivores Heterotroph Heterotrophic nutrition Insectivore Mesopredators Mesopredator release hypothesis Omnivores Optimal foraging theory Planktivore Predation Prey switching
Decomposers	Chemoorganoheterotrophy Decomposition Detritivores Detritus
Microorganisms	Archaea Bacteriophage Lithoautotroph Lithotrophy Marine Microbial cooperation Microbial ecology Microbial food web Microbial intelligence Microbial loop Microbial mat Microbial metabolism Phage ecology
Food webs	Biomagnification Ecological efficiency Ecological pyramid Energy flow Food chain Trophic level
Example webs	Lakes Rivers Soil Tritrophic interactions in plant defense Marine food webs cold seeps hydrothermal vents intertidal kelp forests North Pacific Gyre San Francisco Estuary tide pool
Processes	Ascendency Bioaccumulation Cascade effect Climax community Competitive exclusion principle Consumer–resource interactions Copiotrophs Dominance Ecological network Ecological succession Energy quality Energy systems language f-ratio Feed conversion ratio Feeding frenzy Mesotrophic soil Nutrient cycle Oligotroph Paradox of the plankton Trophic cascade Trophic mutualism Trophic state index
Defense, counter	Animal coloration Anti-predator adaptations Camouflage Deimatic behaviour Herbivore adaptations to plant defense Mimicry Plant defense against herbivory Predator avoidance in schooling fish

v t e Ecology: Modelling ecosystems: Other components
Population ecology	Abundance Allee effect Consumer-resource model Depensation Ecological yield Effective population size Intraspecific competition Logistic function Malthusian growth model Maximum sustainable yield Overpopulation Overexploitation Population cycle Population dynamics Population modeling Population size Predator–prey (Lotka–Volterra) equations Recruitment Small population size Stability Resilience Resistance Random generalized Lotka–Volterra model
Species	Biodiversity Density-dependent inhibition Ecological effects of biodiversity Ecological extinction Endemic species Flagship species Gradient analysis Indicator species Introduced species Invasive species / Native species Latitudinal gradients in species diversity Minimum viable population Neutral theory Occupancy–abundance relationship Population viability analysis Priority effect Rapoport's rule Relative abundance distribution Relative species abundance Species diversity Species homogeneity Species richness Species distribution Species–area curve Umbrella species
Species interaction	Antibiosis Biological interaction Commensalism Community ecology Ecological facilitation Interspecific competition Mutualism Parasitism Storage effect Symbiosis
Spatial ecology	Biogeography Cross-boundary subsidy Ecocline Ecotone Ecotype Disturbance Edge effects Foster's rule Habitat fragmentation Ideal free distribution Intermediate disturbance hypothesis Insular biogeography Land change modeling Landscape ecology Landscape epidemiology Landscape limnology Metapopulation Patch dynamics r/K selection theory Resource selection function Source–sink dynamics
Niche	Ecological niche Ecological trap Ecosystem engineer Environmental niche modelling Guild Habitat marine habitats Limiting similarity Niche apportionment models Niche construction Niche differentiation Ontogenetic niche shift
Other networks	Assembly rules Bateman's principle Bioluminescence Ecological collapse Ecological debt Ecological deficit Ecological energetics Ecological indicator Ecological threshold Ecosystem diversity Emergence Extinction debt Kleiber's law Liebig's law of the minimum Marginal value theorem Thorson's rule Xerosere
Other	Allometry Alternative stable state Balance of nature Biological data visualization Ecological economics Ecological footprint Ecological forecasting Ecological humanities Ecological stoichiometry Ecopath Ecosystem based fisheries Endolith Evolutionary ecology Functional ecology Industrial ecology Macroecology Microecosystem Natural environment Regime shift Sexecology Systems ecology Urban ecology Theoretical ecology
Outline of ecology

Species richness

Sampling considerations

Trends in species richness

Applications

See also

References

Further reading