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9.1.2. Measurement of Biodiversity


Biodiversity is measured by two major components:


i. species richness, and


ii. species evenness.


(i) Species richness


It is the measure of number of species found in a community


a) Alpha diversity

It refers to the diversity within a particular area or ecosystem, and is usually expressed by the number of species (i.e., species richness) in that ecosystem.

b) Beta diversity


It is a comparison of diversity between ecosystems, usually measured as the change in amount of species between the ecosystems

c) Gamma diversity


It is a measure of the overall diversity for the different ecosystems within a region.


(ii) Species evenness


It measures the proportion of species at a given site, e.g. low evenness indicates that a few species dominate the site.