Community Diversity

An ecosystem is a community of living and non-living components that interact in an area. This can be as large as the earth itself or a forest full of plants and animals, or as small as a stomach with its array of microbial inhabitants. Ecosystem health can be measured in different ways, but one good indicator is biodiversity, a measure of the variety of biological species in an ecosystem.

We can evaluate biodiversity using a measure called the Shannon-Wiener Index, proposed by Claude Shannon and Norbert Wiener in the 1940s. The Shannon-Wiener Index is a unitless measurement, calculated as H. The index uses two variables: species richness, or the number of species present, indicated by K, and species evenness, or proportion of each species, indicated by PI. Species richness is the number of unique species in an ecosystem. This example has seven. Species evenness measures how species in an ecosystem are distributed. This means that an ecosystem in which the different species have similar numbers is more even than one where one or two species account for most of the organisms, like this one, relatively overrun with hares.

Now that we know what to measure, let's learn how to measure b