Factoring species, non-species values and threats into biodiversity prioritisation across the ecoregions of Africa and its islands.

摘要

Biodiversity in Africa, Madagascar and smaller surrounding islands is both globally extraordinary and increasingly threatened. However, to date, no analyses have effectively integrated species values (e.g., richness, endemism), non-species values (e.g., migrations, intact assemblages), and threats into a single assessment of conservation priorities. We present such an analysis for the 119 ecoregions of Africa, Madagascar and smaller islands. Biodiversity was not evenly distributed across Africa and patterns vary somewhat among taxonomic groups. Analyses of most vertebrates (i.e., birds, mammals, amphibians) tend to identify one set of priority ecoregions, while plants, reptiles, and invertebrates highlight additional areas. Non-species biological values were not correlated with species measures and thus indicate another set of ecoregions. Combining species and non-species values was therefore crucial for assembling a comprehensive portfolio of conservation priorities across Africa. Different conservation approaches are required in the two sets of priority ecoregions. In Class I ecoregions, most of the ecoregions are found on offshore islands or continental habitat islands or mountains, in which the conservation approach would be to maintain the current protected area networks, developing targeted new areas - often with the collaboration management support of the local populations. In the Class III ecoregions, with low human populations correlating with low rates of narrow endemism and species richness patterns that are distributed across huge tracts of land, the appropriate conservation are large scale, extensive, and not focused on smaller scale patterns of endemism. Threats to biodiversity were also unevenly distributed across Africa. We calculated a synthetic threat index using remaining habitat, habitat block size, degree of habitat fragmentation, coverage within protected areas, human population density, and the extinction risk of species. This threat index was positively correlated with all three measures of biological value (i.e., richness, endemism, non-species values), indicating that threats tend to be focused on the region's most important areas for biodiversity. Integrating biological values with threats allows identification of two distinct sets of ecoregion priority. First, highly imperilled ecoregions with many narrow endemic species that require focused actions to prevent the loss of further habitat leading to the extinction of narrowly distributed endemics. Second, less threatened ecoregions that require maintenance of large and well-connected habitats that will support large-scale habitat processes and associated area-demanding species. By bringing these data together, we can be much more confident that our set of conservation recommendations serves the needs of biodiversity across Africa, and that the contribution of different agencies to achieving African conservation can be firmly measured against these priorities..