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BioDiversityBiodiversity refers to the degree of variety among living organisms that occur at a place. Ordinarily, greater biodiversity is characteristic of "healthier" ecosystems--ones with greater ability to resist stress and disturbance, and able to sustain greater numbers of organisms in good health. There are various ways to express biodiversity (see below). Certain distinct areas of the world harbor exceptionally high numbers of coexisting species. For example, there are nearly 11,000 different kinds of flowering plants on the island of Borneo (in the Malay hot spot) alone. Most hot spots are at low latitude and/or mountainous locations, island archipelagos, or where warm ocean currents adjoin "inland" seas. On the map below, the hot spot names are my own and not "official".
Alpha diversity ("species richness") is the most common means of expressing biodiversity.
Note that various creatures above occur in unlike frequencies (populations) and locations. The characteristic pattern or arrangement of multiple occurrences of an organism is its dispersion. Be sure not to confuse dispersion (the pattern) with dispersal (the process of relocating into that locational position).
Beta diversity ("habitat patchiness") expresses the variety of life at a place with emphasis on the mixture of communities, rather than particular kinds of creatures.
Gamma diversity ("affinity") expresses the relative frequencies of organisms shared in common between multiple regions. In the crude example below the regions are continental realms (most isolated has the smallest index number), but expressions of gamma diversity are possible between marine or aquatic areas, or between regions of other sizes, as well. Gamma diversity, regardless of region type or scale, indicates the degree of geographic sharing or isolation.
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