, Volume 10, Issue 4, pp 243-256

The biodiversity challenge: Expanded hot-spots analysis

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Summary

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 ‘hot-spot’ 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 eight such areas, four of them in tropical forests and four in Mediterranean-type zones. The analysis reveals that the four tropical-forest areas contain at least 2,835 endemic plant species in 18,700 km2, or 1.1 percent of Earth's plant species in 0.013 percent of Earth's land surface; and that the four Mediterranean-type areas contain 12,720 endemic plan: species in 435,700 km2, or 5.1 percent of Earth's plant species in 0.3 percent of the Earth's land surface. Taken together, these eight hot-spot areas contain 15,555 endemic plant species in 454,400 km2, or 6.2 percent of Earth's plant species in 0.3 percent of Earth's land surface. This is to be compared with the earlier hot-spots analysis of 10 tropical-forest areas, with 34,400 endemic plant species in 292,000 km2, or 13.8 percent of Earth's plant species in 0.2 percent of Earth's land surface.

Taking all 18 hot-spot areas together, we find they support 49,955 endemic plant species, or 20 percent of Earth's plant species, in 746,400 km2, or 0.5 percent of Earth's land surface. This means that one fifth of Earth's plant species are confined to half of one percent of the Earth's land surface — and they occur in habitats that are mostly threatened with imminent destruction.

By concentrating on these hot-spot areas where needs are greatest and where the pay-off from safeguard measures would be greatest, conservationists can engage in a more systematised response to the challenge of large scale impending extinctions.

Dr Norman Myers is a consultant in environment and development, a member of this journal's Advisory Board, and a regular contributor to the journal. He is a Senior Fellow of World Wildlife Fund — US. This paper enlarges on an important theme developed by Dr Myers in a contribution which appeared inThe Environmentalist,8(3), 187–208. The research for this paper has been supported by the MacArthur Foundation, Chicago, USA.