Community (ecology)

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It has been suggested that Biocoenosis be merged into this article or section. (Discuss)

In ecology, a community is an assemblage of populations of different species, interacting with one another.

The term is used in various ways with slight differences in meaning. Sometimes it is limited to specific places, times, or subsets of organisms. For example, "the fish community of Lake Ontario before industrialization".

Another usage difference is whether a community is defined based on evolutionary taxonomy and biogeography, or based on function and behavior regardless of genetic relationships. For example, a plant community of the first type might be called "oak-hickory forests", while one of the second type might be called "temperate deciduous forests". The first sense of the term "community" is related to broad concepts such as ecozones and floristic provinces (such as the Neotropic ecozone or the Cape floristic region), while the second sense is related to biomes (such as the Temperate coniferous forests) (Akin, pp. 168-169).

1 Interspecific interactions
2 See also
3 References
4 External links

Interspecific interactions

Species interact in three ways: competition, predation and mutualism.

Competition

In some situations, species compete with each other for resources, which may negatively affect the growth rate, size, or biomass of the population. This is a double negative (- -) interaction. Two types of competition may occur:

Interference competition: occurs when one bobby species attacks, or consumes the resources, of another. Examples include a lion chasing a hyena from a kill, or a plant releasing allelopathic chemicals to impede the growth of a competing species.
Exploitative competition: occurs via the consumption of resources. When an individual of one species consumes a resource (e.g., food, hiding place, light source, etc.), that resource is no longer available to be consumed by a member of a second species. Exploitative competition is more common in nature. Competition may limit average population size and the number of species that coexist in a community

Predation

Predation is hunting another species for food. This is a positive-negative (+ -) interaction in that the predator species benefits while the prey species is harmed. Some predators kill their prey before eating them (e.g., a hawk killing a mouse). Other predators are parasites that feed on prey while alive (e.g., a vampire bat feeding on a cow). Herbivores feed on plants (e.g., a cow grazing). Predation may affect the population size of predators and prey and the number of species coexisting in a community.

Mutualism

Mutualism is a symbiotic interaction between species in which both benefit, and is thus a double positive (+ +) interaction. Examples include Rhizobium bacteria growing in nodules on the roots of legume plants and insects pollinating the flowers of angiosperms.

References

Akin, Wallace E. (1991). Global Patterns: Climate, Vegetation, and Soils. University of Oklahoma Press. ISBN 0-8061-2309-5.
Ricketts, Taylor H., Eric Dinerstein, David M. Olson, Colby J. Loucks et al. (WWF) (1999). Terrestrial Ecoregions of North America: a conservation assessment. Island Press. ISBN 1-55963-722-6.