The biodiversity challenge: expanded hot-spots analysis

Abstract

This paper aims to throw light on the mass extinction that is overtaking Earth's species. Using an analytic methodology developed for an earlier partial assessment, it focuses on a series of "hotspot" areas, these being areas that a) feature exceptional concentrations of species with high levels of endemism and b) face exceptional threats of destruction. The paper identifies another 8 such areas, 4 of them in tropical forests and 4 in Mediterranean-type zones. The analysis reveals that the 4 tropical-forest areas contain at least 2835 endemic plant species in 18,700 sq. km, or 1.1% of Earth's plant species in 0.013% of Earth's land surface; and that the 4 Mediterranean-type areas contain 12,720 endemic plant species in 435,700 sq. km, or 5.1% of Earth's plant species in 0.3% of the Earth's land surface. Taken together, these 8 hotspot areas contain 15,555 endemic plant species in 454,400 sq. km, or 6.2% of Earth's plant species in 0.3% of Earth's land surface. This is to be compared with the earlier hotspot analysis of 10 tropical-forest areas, with 34,400 endemic plant species in 292,00 sq. km, or 13.8% of Earth's plant species in 0.2% of Earth's land surface. Taking all 18 hot-spot areas together, the authors find they support 49,995 endemic plant species, or 20% of Earth's plant species, in 746,400 sq. km, or 0.5% of Earth's land surface. This means that one-fifth of Earth's plant species are confined to 0.5% of the Earth's land surface--and they occur in habitats that are mostly threatened with imminent destruction. By concentrating on these hotspot areas where needs are greatest and where the pay-off from safeguard measures would be greatest, conservationists can engage in a more systematized response to the challenge of large-scale impending extinctions.