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The Shannon index is the most commonly used way to quantitatively determine species diversity, H, as modeled by the following equation: = = The Shannon index factors in both species evenness and species richness, as represented by the variables p i and s, respectively. The lowest possible value of H is zero, and the higher a community’s H ...
Relative species abundance is a component of biodiversity and is a measure of how common or rare a species is relative to other species in a defined location or community. [1] Relative abundance is the percent composition of an organism of a particular kind relative to the total number of organisms in the area.
A diversity index is a method of measuring how many different types (e.g. species) there are in a dataset (e.g. a community).Diversity indices are statistical representations of different aspects of biodiversity (e.g. richness, evenness, and dominance), which are useful simplifications for comparing different communities or sites.
SAD is a measurement of how common, or rare species are within an ecosystem. [5] This allows researchers to assess how different species are distributed throughout an ecosystem. SAD is one of the most basic measurements in ecology and is used very often, therefore many different methods of measurement and analysis have developed. [5]
Rarefaction only works well when no taxon is extremely rare or common [citation needed], or when beta diversity is very high. Rarefaction assumes that the number of occurrences of a species reflects the sampling intensity, but if one taxon is especially common or rare, the number of occurrences will be related to the extremity of the number of ...
The first approach is to calculate a weighted generalized mean of the within-subunit species proportional abundances, and then take the inverse of this mean. The second approach is to calculate the species diversity for each subunit separately, and then take a weighted generalized mean of these. [4] [13] If the first approach is used, the ...
The Mean Species Abundance Index (MSA) calculates the trend in population size of a cross section of the species. It does this in line with the CBD 2010 indicator for species abundance. [10] The Biodiversity Intactness Index (BII) measures biodiversity change using abundance data on plants, fungi and animals worldwide.
Morisita's overlap index, named after Masaaki Morisita, is a statistical measure of dispersion of individuals in a population. It is used to compare overlap among samples (Morisita 1959). This formula is based on the assumption that increasing the size of the samples will increase the diversity because it will include different habitats (i.e ...