Biology unit 3

What are the levels in which biodiversity can be measured

Species, genetic and ecosystem diversity.

What does ecosystem diversity refer to?

The variety of different types of habitats or ecosystems available

What are the methods of determining the diversity of species

Species richness, species evenness, percentage cover, percentage frequency and Simpsons diversity index

Species richness 

This is the number of different species in an ecosystem. It takes no notice of abundance and gives as much weight to those species which have very few individuals as to those who have thousands.

Species Evenness

This is a measure of the relative abundance of the different species. A community dominated by one or two species is considered to be less diverse than one in which several different species have a similar abundance.

Percentage cover

If we want to know what kind of plants are in a particular habitat, and how many there are of each species, it is usually impossible to go and count each and every one present. Therefore, we use a quadrat and estimate percentage cover.

Percentage cover

This is the probability that a species will be found within a single quadrat.

Percentage frequency = (number of quadrats in which the species is found/total number of quadrats) x 100