Showing papers on "Diversity index published in 1984"
TL;DR: The hypotheses that vegetation structural diversity and prey availability determine alpha diversity were examined for scrub- and meadow-inhabiting web spider species assemblages along elevational gradients in Costa Rica and California.
Abstract: The hypotheses that vegetation structural diversity and prey availability determine alpha diversity were examined for scrub- and meadow-inhabiting web spider species assemblages along elevational gradients in Costa Rica and California Prey availabilities were estimated by sticky trap catches, using only the orders and size classes of insects actually captured by the spiders The measured component of vegetation structural diversity was the maximum tip height in 20 cm increments from 0 to 20 m Spider species diversity and vegetation tip height diversity were both expressed by the Inverse Simpson Index Web spider species diversity is highly significantly correlated with vegetation tip height diversity Prey availability is not a significant predictor of web spider species diversity in these habitats
253 citations
TL;DR: In this paper, the benthic invertebrates of the Dolores River in southwest Colorado were sampled during three seasons in an area of historic mine drainage, and diversity indices used to assess the effects of this stress on the invertebrate community were MargalePs, Simpson's, Shannon-Weaver's, Brillouin's, and the Biotic Condition Index.
Abstract: The benthic invertebrates of the Dolores River in southwest Colorado were sampled during three seasons in an area of historic mine drainage. Benthic density exhibited significantly lower values below the mine drainage. However, the number of species did not decrease significantly, indicating that the effect of the mine drainage was primarily non-selective (i.e. favoring no one taxon). This pattern was seasonal with the least effects evident in summer and the greatest effects found in spring. Diversity indices used to assess the effects of this stress on the invertebrate community were MargalePs, Simpson's, Shannon-Weaver's, Brillouin's, and the Biotic Condition Index. None of the indices tested adequately responded to a decreasing trend in the benthic density when number of species remained constant. The indices did respond to a combination of low density and number of species or to the predominant representation by one species. The Biotic Condition Index actually increased at the stations with the lowest density and number of species. Diversity indices appear to be inadequate in assessing a non-selective stress.
32 citations
TL;DR: In this paper, the SHANNON index was used to evaluate the diversity of phytoplankton in 23 water bodies of different trophic status and found that high diversity was obtained in meso-and slightly eutrophic waters, whereas a low diversity was observed in oligo-or highly eutrophic waters.
Abstract: Phytoplankton diversity in 23 water bodies of different trophic status was evaluated by the SHANNON index. High diversity was obtained in meso- and slightly eutrophic waters, whereas a low diversity was observed in oligo- or highly eutrophic waters.
22 citations
TL;DR: Seven diversity indices were calculated for each of fifty-eight microcosm communities initiated from equal density inoculations of fourteen algal species; the Shannon-Wiener index was best according to two of the discriminating methodologies and second best using the other techniques.
Abstract: Seven diversity indices were calculated for each of fifty-eight microcosm communities. All fifty-eight communities were initiated from equal density inoculations of fourteen algal species. Each microcosm developed in one of six controlled experimental environments; the environments differing only in their temporal patterns of disturbance. Five linear discriminating techniques were used to evaluate the diversity index most useful for discriminating between these environments. The Shannon-Wiener index was best according to two of the discriminating methodologies and second best using the other techniques. Evenness was best when the Shannon-Wiener index was second best and vice versa.
21 citations
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TL;DR: The results discussed in this paper, are a continuation of research on diversity as presented by Gini (1912) and provide a parametric extension of the Gini diversity index which may provide different coefficients of diversity for two quite different looking populations.
1 citations