Community Density and Stability

Community Density and Stability - are older because they...

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Community Density and Stability Communities are made up of species adapted to the conditions of that community. Diversity and stability help define a community and are important in environmental studies. Species diversity decreases as we move away from the tropics. Species diversity is a measure of the different types of organisms in a community (also referred to as species richness ). Latitudinal diversity gradient refers to species richness decreasing steadily going away from the equator. A hectare of tropical rain forest contains 40-100 tree species, while a hectare of temperate zone forest contains 10-30 tree species. In marked contrast, a hectare of taiga contains only a paltry 1-5 species! Habitat destruction in tropical countries will cause many more extinctions per hectare than it would in higher latitudes. Environmental stability is greater in tropical areas, where a relatively stable/constant environment allows more different kinds of species to thrive. Equatorial communities
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Unformatted text preview: are older because they have been less disturbed by glaciers and other climate changes, allowing time for new species to evolve. Equatorial areas also have a longer growing season. The depth diversity gradient is found in aquatic communities. Increasing species richness with increasing water depth. This gradient is established by environmental stability and the increasing availability of nutrients. Community stability refers to the ability of communities to remain unchanged over time. During the 1950s and 1960s, stability was equated to diversity: diverse communities were also stable communities. Mathematical modeling during the 1970s showed that increased diversity can actually increase interdependence among species and lead to a cascade effect when a keystone species is removed. Thus, the relation is more complex than previously thought....
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