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Some Indices of Diversity
Author(s) -
Dickman Mike
Publication year - 1968
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1934512
Subject(s) - trophic level , diversity index , relative species abundance , community structure , abundance (ecology) , index (typography) , diversity (politics) , ecology , biomass (ecology) , species diversity , productivity , biology , mathematics , species richness , economics , sociology , macroeconomics , world wide web , computer science , anthropology
An index of diversity (H) based on the Shannon—Weaver formula, H = — Σ n 1 P i log P i , fails to reflect significant changes in a community's structure because it is only sensitive to changes in relative abundance of a few of the trophic levels of a community. Over two thirds of the species encountered in a typical plankton sample had no significant effect on the index of diversity (H), calculated for that sample. To overcome this, the Shannon—Weaver formula was twice altered by redefining P i in order to give a new index of community diversity which was sensitive to changes in community structure. P i defined in terms of relative biomass (H b ) failed to improve the index substantially and P i was then successfully defined in terms of relative productivity (H p ). An index of community diversity sensitive to changes in relative abundance of all the trophic levels, such as the index H p , appears to be a necessary prerequisite to comparative community studies.