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Biologists most often define biodiversity as the "totality of genes, species and ecosystems of a region". [8] [9] An advantage of this definition is that it presents a unified view of the traditional types of biological variety previously identified: taxonomic diversity (usually measured at the species diversity level) [10]
Species richness [2] is the number of species present in a given area. Species diversity [3] is the relationship between species evenness and species richness. There are many ways to measure biodiversity within a given ecosystem. However, the two most popular are Shannon-Weaver diversity index, [4] commonly referred to as Shannon diversity ...
Species diversity is the number of different species that are represented in a given community (a dataset). The effective number of species refers to the number of equally abundant species needed to obtain the same mean proportional species abundance as that observed in the dataset of interest (where all species may not be equally abundant).
In other related studies, around 1.9 million extant species are believed to have been described currently, [9] but some scientists believe 20% are synonyms, reducing the total valid described species to 1.5 million. In 2013, a study published in Science estimated there to be 5 ± 3 million extant species on Earth although that is disputed. [10]
In the article The Influence of Functional Diversity and Composition on Ecosystem Processes, [1] scientists reported on an experiment in which they studied the effects of plant species diversity, functional diversity, and functional composition on ecosystem processes, as measured in six response variables (productivity, plant % N, plant tot.
A diversity index is a method of measuring how many different types (e.g. species) there are in a dataset (e.g. a community). Some more sophisticated indices also account for the phylogenetic relatedness among the types. [ 1 ]
Species evenness is combined with species richness, (the number of species in the community), in order to determine species diversity, which is an important measure of community structure. Community structure in turn provides the quantitative basis needed to create hypotheses and experiments that help to increase understanding of how ...
Graph shows principles of intermediate disturbance hypothesis: I. at low levels of ecological disturbance species richness decreases as competitive exclusion increases, II. at intermediate levels of disturbance, diversity is maximized because species that thrive at both early and late successional stages can coexist, III. at high levels of ...