Terrestrial Amphibian Irreplaceability - ACE [ds2719]

Amphibian Irreplaceability, Areas of Conservation Emphasis (ACE), version 3.0.

Terrestrial Irreplaceability is a measure of the uniqueness of habitat areas for rare endemic species in the landscape, and is one measurement used to describe the distribution of overall species biodiversity in California for the California Department of Fish and Wildlife (CDFW) Areas of Conservation Emphasis Project (ACE). Other measures of terrestrial species biodiversity included in the ACE terrestrial biodiversity summary are native species richness and rare species richness.

Here, terrestrial irreplaceability represents the relative importance of each hexagon based on the uniqueness of habitat areas present for California rare endemic and near-endemic species. Hexagons with a high irreplaceability weight contain species or habitat conditions that occur in few places in the landscape. These areas may be of high conservation value due to their unique contribution to biodiversity. The data provides, 1) a count of the total number of endemic species per taxonomic group in each hexagon based on documented species occurrence information, and 2) the irreplaceability weight, based on the rarity-weighted index (RWI), which weights the species count by the extent of the distribution for each species, so hexagons providing habitat for narrowly distributed species are given a higher score. Areas with a high RWI support rare species with few documented occurrences; these areas would be expected to support unique habitats or suites of species that are limited in distribution. The data can be used to view the distribution of rare endemic species in California, and to identify areas of high irreplaceability. Users can view a list of species that contribute to the biodiversity summary for each hexagon.