A comparison of three diversity indices based on their components of richness and evenness

TM DeJong - Oikos, 1975 - JSTOR
TM DeJong
Oikos, 1975JSTOR
Species diversity is one of the basic concepts of ecology that has been used to characterize
communities and ecosystems. At first glance the concept appears to be rather simple but
ecologists and mathematicians have been searching for ways to express the various
aspects of diversity since 1922 (Gleason 1922) even though the term did not appear in the
literature until 1943 (Fisher et al. 1943). Consequently, the concept of species diversity has
been defined in many ways, and several different indices have been developed to express …
Species diversity is one of the basic concepts of ecology that has been used to characterize communities and ecosystems. At first glance the concept appears to be rather simple but ecologists and mathematicians have been searching for ways to express the various aspects of diversity since 1922 (Gleason 1922) even though the term did not appear in the literature until 1943 (Fisher et al. 1943). Consequently, the concept of species diversity has been defined in many ways, and several different indices have been developed to express it. The objective of this paper is to compare three diversity indices in their sensitivity to the two aspects of diversity: species richness and species evenness. Species richness is usually thought of as the number of species per sample. Species evenness (equitability) is a parameter which indicates relative abundances of the various species in a sample. Species evenness increases as species are more evenly distributed in a sample such that maximum evenness is obtained when all the species are equally abundant. Species diversity increases as the number of species per sample increases and as the abundances of species within a sample become more even (Pielou 1969, Kricher 1972). The diversity indices chosen are those of Simpson, Shannon, and McIntosh.
2. Diversity indices Simpson (1949) introduced an index of diversity which is a measure of concentration of species. Its numerical values increase as diversity decreases (Risser and Rice 1971). A common variation of Simpson's index yields values on a probability scale from 0.0 to 1.0 in ascending order with increased diversity
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