A comprehensive index for threatened biodiversity valuation

We present a new comprehensive index for mapping the relative conservation value of threatened biodiversity.The index is based on explicit criteria to (1) select threatened species according to regional government re-sponsibility for species’conservation; (2) combine species’presence by means of weighting factors based ondifferences in threat status, sensitivity to disturbance, functional role, and amount of knowledge; and (3) mapspecies distributions at the scale of 1 km × 1 km UTM squares or lower from the information available. We testedthe performance of the index in the forest of Andalusia (southern Spain), an extensive European region of87,268 km2, with 43,864 km2(ca. 50%) classified as forest habitats. All species included in the Annexes of theEuropean Birds and Habitats Directives inhabiting the target area, plus the regionally endemic species either‘Critically Endangered’or‘Endangered’not (yet) covered by the Directives were selected. Thefinal list included224 species: 81 plants, 76 birds, 31 mammals, 22 arthropods, six reptiles,five amphibians, and three mollusks.Fine-scale distribution maps were available for 108 species (48%). The remaining maps were downscaled frompublished 10 km × 10 km UTM maps using knowledge on species’habitat requirements and land-use maps. Weoverlapped thefine-scale maps with the 86,546 forest tiles of the Andalusian Forest Map and weighted presencesby a factor of relative conservation estimated for each species to obtain an index of the relative conservation ofeach forest tile. Index values were higher in protected areas, and in different forest habitats according to ex-pected numbers of endangered species. Index values were correlated with the existence value of threatenedspecies, but the index underestimate existence values especially for the most valuable tiles. The proposed indexallows mapping the relative conservation value of threatened biodiversity by integrating knowledge on allthreatened species into a single variable. Integration is based on explicit methodological criteria for speciesselection, combination of relative conservation values, and estimation of downscaled maps. Accurate mappingand synthetic summary of compulsory data on the conservation status of all species present in a territory adviseits extended use for threatened biodiversity valuation in both Europe and elsewhere.

Thispaper is a contribution to the projects RECAMAN (contract n°NET165602; www.recaman.es), VEABA (ECO2013-42110-P) andTrEnGood (ECO2017-84461-R), funded by the Andalusian and theSpanish agencies, respectively

Peer reviewed