A glossary of definitions for terms relating to biodiversity, ecosystems services and conservation.
All definitions are referenced, where possible preference has been given to internationally recognised definitions (for example those defined by international conventions or agreements). The terms have been chosen to support understanding of biodiversity and conservation issues, and terms relating to biodiversity loss are complemented by those relating to conservation responses supported by international conservation organisations, governments, scientists and business sectors.
More detailed explanations are provided for a number of key terms, to provide further background information.
The terms can be filtered by category to aid in the navigation of the many definitions.
The area contained within the shortest continuous imaginary boundary which can be drawn to encompass all the known, inferred or projected sites of occurrence, excluding cases of vagrancy.1
Extent of occurrence is a parameter that measures the spatial spread of the areas currently occupied by the taxon. The intent behind this parameter is to measure the degree to which risks from threatening factors are spread spatially across the taxon’s geographical distribution. It is not intended to be an estimate of the amount of occupied or potential habitat, or a general measure of the taxon’s range2. Extent of occurrence can often be measured by a minimum convex polygon (the smallest polygon in which no internal angle exceeds 180 degrees and which contains all the sites of occurrence)1
International Union for Conservation of Nature (IUCN) 20121
International Union for Conservation of Nature (IUCN) 20142