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.