he word biodiversity refers to the diversity of biological life. According to a widely used definition biodiversity can be identified on three levels of organisation: genes, species and ecosystems. Genetic diversity means the variation of genes within a certain group of individuals. Normally the focus is on some seemingly uniform group such as a population or a species. Species diversity is most often measured as the number of species present in a certain area or ecosystem. Ecosystem diversity occurs on a large spatial scale. It means the diversity of different ecosystem types (e.g. herb-rich forests, raised bogs or humic lakes) in a given area. One possible level of interest may be the diversity of ecosystems in Finland, for example.

Biodiversity is often used as a measure of the health of biological systems. This is the main use of the concept on these pages