Dynamic aspects of diversity

Autor: Ramón Margalef
Rok vydání: 1994
Předmět:
Zdroj: Journal of Vegetation Science. 5:451-456
ISSN: 1654-1103
1100-9233
DOI: 10.2307/3235970
Popis: Ecological diversity is viewed as a measure of information, as the variety of messages compounded with the number of individuals belonging to different species. Two limit situations of diversity are indicated: a chemostat-like system tending to become monospecific, and a Noah's ark or museum situation with an infinite number of species each represented by just one specimen. In a dynamic approach, two differential equations for S, the number of species, and N, the number of individuals, can be considered. A new index of diversity is proposed based on these two equations. The concept of diversity spectrum is proposed for a series of diversity measurements in samples of increasing size and related to the concept of minimal area. Diversity can also be measured on non-taxonomic categories, e.g. size classes. The contrast between the two boundary types, limes convergens (ecotone) and limes divergens (ecocline), is em- phasized. The nature of the difference between them is com- pared with that of tension zones between fluids in contact. Differences between ecosystems can be characterized through differences in the ratio P/B (Production/Biomass) and a boundary situation is imagined including two systems with P/B different values and different diversity levels. Some ex- amples are presented from communities in streams.
Databáze: OpenAIRE
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