Ecological measurement of biodiversity

From the above discussion, it can be appreciated that the primary interest in measuring

biodiversity is that biodiversity level is an indicator of well-being of ecological systems, which

also dictate the productivity to humankind of those systems. Biodiversity has two dimensions:

richness (variety) and abundance (number). Ecologists typically utilise three types of

biodiversity measure:

• Species richness indices – a measure of the number of species in a defined

sampling unit.

• Species abundance indices – compares the level of evenness amongst numbers of each

species versus unevenness (unequal). Usually some species are abundant whereas

most are not i.e. a few species dominate.

• Proportional abundance indices – which seek to summarise richness and evenness into

a single figure e.g. Shannon and Simpson indices.