West, N.E. 1992. Biodiversity of Rangelands. J. Range Mgt 46:2-13
Here we see that biodiversity has several components. The species-specific maintenance of genetic diversity that allows for adaptation to environmental change, which requires adequate numbers to avoid extinction. Species diversity is generally considered the numbers of species in an area, but must include consideration of population numbers in order to sustain a population. For example, if insufficient numbers to provide genetic diversity or reproduce, then extinction could occur. Community or ecosystem diversity includes the range of structural components in a habitat or ecosystem that allows species to flourish as well as their arrangement that provides the necessary habitat features for survival and growth. Landscape diversity considers the variety of ecosystems, habitats and their structural features that occur across the land along with the ability of population migration to occur, i.e. connectedness (lack of fragmentation). It also considers the resilience of the ecosystem to withstand disturbance.
