pielou's evenness index pdf

Microbial community diversity concerns both taxon richness and evenness (Wang et al., 2012), so the Shannon–Wiener Index and rank–abundance distribution curve were used to investigate species richness and evenness of the periphyton community during the 30 days' domestication (Bates et al., 2013).

An area of 100 m×100 m plot was randomly selected in each meadow. All relationships between species richness and evenness, and between SLA and species relative abundance along the successional gradient were explored in only 6 meadows of different successional ages, yet the differences in meadow successional age show clear consistent negative relationship between species richness and evenness (Considered together, our results demonstrate that niche-preemption is an important mechanism that influences the pattern of the relationship between species evenness and richness along the successional gradient in sub-alpine meadows, and that this relationship is sensitive to the spatial scale of observation. PLOS is a nonprofit 501(c)(3) corporation, #C2354500, based in San Francisco, California, US

By continuing you agree to the Copyright © 2020 Elsevier B.V. or its licensors or contributors. These studies date back to DeBenedictis Empirical studies of the relationship between species richness and evenness have also reported contrasting findings. Conversely, the dominance index D and Hill’s diversity number evenness E 1,0 both satisfy the replication principle (Taillie, 1979, Smith and Wilson, 1996). Considering all results together, we can conclude that such niche differentiation and spatial scale effects may help to explain the maintenance of high species richness in sub-alpine meadow communities.Diversity is one of the most important community attributes which can determine stability, productivity and migration Several theoretical studies have assumed that species richness and evenness should be independent or positively correlated.

Grasses were sampled within quadrats in August during the peak of the growing season.

Earlier observational research suggested that species richness was positively correlated with evenness Species-area relationships have clearly demonstrated the effect of spatial scale on species richness Many investigations indicate that different abundance models combined with trait-specific methods can provide us a very powerful tool to explore the mechanisms of community assembly Our study system, the sub-alpine plant community in the Qinghai-Tibetan Plateau, is particularly well suited to address important questions concerning species richness and evenness of communities. March 1973. We selected 6 quadrat sizes which increase exponentially in area: 0.5 m×0.5 m (400 quadrats were sampled), 0.5 m×1 m (200), 1 m×1 m (100), 1 m×2 m (50), 2 m×2 m (25), 2 m×4 m (10).For fitting species abundance models which have different evenness in abundance, we firstly created a set of communities ranging from the most even one where all the species share the same abundance, to the most uneven one in which the first species has abundance one less than the community size (The result of the one-way ANOVA analysis of the variation of evenness along the successional age.This work was done in the Research Station of Alpine Meadow and Wetland Ecosystems of Lanzhou University.Conceived and designed the experiments: SZ HZ. The area of each meadow was at least 120 ha, and had similar orientation, aspect and slope position. In addition, in the last two decades, numerous information–theoretical indices, such as the landscape dominance index, have been extensively applied to characterize landscape diversity in space and time. This is consistent with Our results clearly demonstrate that the strength of the relationship between species richness and evenness weakens with increase in spatial scale.

DeBenedictis (1973) showed that there is a necessary mathematical connection between Pielou’s evenness J and species richness. Volume 54, Issue 2. Here we examine the relationship between species richness(S) and evenness (Pielou’s J′ evenness) using a chronosequence of successional sub-alpine meadow communities in the eastern Qinghai-Tibetan Plateau. Meadows were selected so that meadows with similar successional ages were not closer to each other than to meadows with dissimilar ages. A particular problem with Pielou's index is that it is a ratio of a relatively stable index, H', and one that is strongly dependent on sample size, S.

The communities are of high diversity, and investigations of community attributes are relatively easy Although evenness (J′) varies substantially along the succession gradient (P value of one-way ANOVA = 0.006, Although there are significant differences in the observed J′ along the succession gradient, only the niche-preemption model can fit the observed J′s in these successional meadows at the scale of 0.5 mSpecific leaf area (SLA) varies significantly with successional age. Species richness and evenness are negatively corrected at relatively small scales (0.5 m×0.5 m to 2 m×2 m), but this negative relationship vanishes at larger scales (≥2 m×4 m).