An Index of Evenness and Its Associated Diversity Measure

Bulla, Luis

doi:10.2307/3545713

Cited by 116 publications

(80 citation statements)

References 2 publications

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“…The rarefied number of species present in a sample of n individuals was computed with Coleman's curve (e.g. Colwell and Coddington 1994), whereas the evenness of communities on both host stages was estimated with the index of evenness (E), proposed by Bulla (1994). Similarities in herbivore communities were calculated with the Morisita-Horn index (Magurran 1988).…”

Section: Methodsmentioning

confidence: 99%

Communities of insect herbivores foraging on saplings versus mature trees of Pourouma bicolor (Cecropiaceae) in Panama

Basset

2001

Oecologia

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The arthropod fauna of 25 saplings and of three conspecific mature trees of Pourouma bicolor (Cecropiaceae) was surveyed for 12 months in a tropical wet forest in Panama, with particular reference to insect herbivores. A construction crane erected at the study site provided access to tree foliage in the upper canopy. A similar area of foliage (ca. 370 m 2 ) was surveyed from both saplings and trees, but samples obtained from the latter included 3 times as much young foliage as from the former. Arthropods, including herbivores and leafchewing insects with a proven ability to feed on the foliage of P. bicolor were 1.6, 2.5 and 2.9 times as abundant on the foliage of trees as on that of saplings. The species richness of herbivores and proven chewers were 1.5 (n=145 species) and 3.5 (n=21) times higher on trees than on saplings, respectively. Many herbivore species preferred or were restricted to one or other of the host stages. Host stage and young foliage area in the samples explained 52% of the explained variance in the spatial distribution of herbivore species. Pseudo-replication in the two sampling universes, the saplings and trees studied, most likely decreased the magnitude of differences apparent between host stages in this forest. The higher availability of food resources, such as young foliage, in the canopy than in the understorey, perhaps combined with other factors such as resource quality and enemyfree space, may generate complex gradients of abundance and species richness of insect herbivores in wet closed tropical forests.

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Section: Methodsmentioning

confidence: 99%

Communities of insect herbivores foraging on saplings versus mature trees of Pourouma bicolor (Cecropiaceae) in Panama

Basset

2001

Oecologia

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“…Based on Bulla's index to measure species' evenness (Bulla 1994 When trait space is multi-dimensional, the community's evenness is the average of the FE s calculated for each trait.…”

Section: One-dimensional Indexmentioning

confidence: 99%

A user's guide to functional diversity indices

Schleuter¹,

Daufresne

Massol

et al. 2010

Ecological Monographs

610

541

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Abstract. Functional diversity is the diversity of species traits in ecosystems. This concept is increasingly used in ecological research. Yet its formal definition and measurements are currently under discussion. As the overall behavior and consistency of functional diversity indices have never been described so far, the novice user risks choosing an inaccurate index or a set of redundant indices to represent functional diversity.In our study we closely examine functional diversity indices to clarify their accuracy, consistency, and independency. Following current theory, we categorize them into functional richness, evenness, or divergence indices. We considered existing indices as well as new indices developed in this study. The new indices aimed at remedying the weaknesses of currently used indices (e.g., by taking into account intraspecific variability). Using virtual datasets, we first test whether indices respond to community changes as expected from their category, and second, whether the indices within each category are consistent and independent of indices from other categories. We also test the accuracy of methods proposed for the use of categorical traits.Most classical functional richness indices either failed to describe functional richness or were correlated with functional divergence indices. We therefore recommend using the new functional richness indices which consider intraspecific variability and thus empty space in the functional niche space. In contrast, most functional evenness and divergence indices performed well with respect to all proposed tests. For categorical variables, we do not recommend blending discrete and real-valued traits (except for indices based on distance measures) since functional evenness and divergence have no transposable meaning for discrete traits. Nonetheless, species diversity indices can be applied to categorical traits (using trait levels instead of species) in order to describe functional richness and equitability.

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“…We think it reasonable to base an evenness measure on S for two reasons. First, theoretical studies (e.g., Bulla 1994), are often implicitly built on the assumption of a fixed number of species. These studies provide valuable insight in the general behavior and properties of diversity indices.…”

Section: Connection To Other Parametric Diversity Indicesmentioning

confidence: 99%

Goodness-of-fit measures of evenness: a new tool for exploring changes in community structure

et al. 2011

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Abstract. Growing concern about the fate of biodiversity, highlighted by the Convention on Biological Diversity's 2010 and 2020 targets for stemming biodiversity loss, has intensified interest in methods of assessing change in ecological communities through time. Biodiversity is a multivariate concept, which cannot be well-represented by a single measure. However, diversity profiles summarize the multivariate nature of multi-species datasets, and allow a more nuanced interpretation of biodiversity trends than unitary metrics. Here we introduce a new approach to diversity profiling. Our method is based on the knowledge that an ecological community is never completely even and uses this departure from perfect evenness as a novel and insightful way of measuring diversity. We plot our measure of departure as a function of a free parameter, to generate ''evenness profiles''. These profiles allow us to separate changes due to dominant species from those due to rare species, and relate these patterns to shifts in overall diversity. This separation of the influence of dominance and rarity on overall diversity enables the user to uncover changes in diversity that would be masked in other methods. We discuss profiling techniques based on this parametric family, and explore its connections with existing diversity indices. Next, we evaluate our approach in terms of predicted community structure (following Tokeshi's niche models) and present an example assessing temporal trends in diversity of British farmland birds. We conclude that this method is an informative and tractable parametric approach for quantifying evenness. It provides novel insights into community structure, revealing the contributions of both rare and common species to biodiversity trends.Key words: biodiversity; divergence measures; diversity indices; diversity ordering; diversity profiles; evenness; goodness-of-fit statistics; Hill's diversity numbers; rare species; species abundance distribution.

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An Index of Evenness and Its Associated Diversity Measure

Cited by 116 publications

References 2 publications

Communities of insect herbivores foraging on saplings versus mature trees of Pourouma bicolor (Cecropiaceae) in Panama

Communities of insect herbivores foraging on saplings versus mature trees of Pourouma bicolor (Cecropiaceae) in Panama

A user's guide to functional diversity indices

Goodness-of-fit measures of evenness: a new tool for exploring changes in community structure

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