Global assessments of biodiversity argue for expansion of protected areas in key regions

Special section in journal details new studies

Five articles published in a Special Section in the December 2004 issue of BioScience, the monthly journal of the American Institute of Biological Sciences (AIBS), provide new global assessments of how well protected areas such as parks can safeguard the numerous animal and plant species at risk of becoming extinct. The new analyses lead to the conclusion that although nominally protected areas now approach 12 per cent of the Earth’s land surface, more needs to be done. The studies point to regions that should have high priority in the creation of additional protected areas for biodiversity conservation, and suggest ways to identify specific sites.

The articles employ the framework known as gap analysis, a planning approach based on the assessment of the comprehensiveness of existing protected-area networks and the identification of “gaps” in coverage–species whose distribution means they are nowhere protected.

The first article in the Special Section, by Thomas Brooks of Conservation International and fourteen coauthors, assesses high-quality global databases newly available for conservation planning. It notes that coverage by protected areas varies geographically, but is less than 2 percent for some bioregions, such as the tropical dry forests of Mexico, the mediterranean habitats of Chile, and the temperate grasslands of Southern Africa.

In the second article, Ana S. L. Rodrigues of Conservation International and 21 coauthors build on a previously published global gap analysis to ask how the protected area network could be strategically expanded to improve protection of over 11,000 species of vertebrates. Some 13 percent of 11,633 bird, mammal, amphibian, and turtle species analyzed are wholly unrepresented in protected areas, and almost three quarters are not adequately protected. Amphibians are markedly less well protected than mammals, turtles, or birds. Places identified as urgent priorities for expansion of the network of protected areas fall overwhelmingly in the tropics, with Asia as a high-priority region and islands and mountains often particularly important. In the Western hemisphere, the Andes and neighboring lowland Pacific forests are identified as key areas for expansion of protection. Rodrigues and her coauthors urge more fine-grained analyses in the priority areas. Because many of these areas are in poor countries, the researchers suggest that foundations, corporations, and other institutions should bear much of the cost.

The third article in the Special Section (lead author: Simon Ferrier of the New South Wales Department of Environment and Conservation) introduces a computationally intensive technique for assessing protection of biodiversity based on both the number of species in an area and its “compositional turnover,” a measure of how different the area is from others in terms of species represented. Ferrier’s analysis uses a 5-km global grid and data from over a million localities; it considers 98,000 species of plants and invertebrates. (Threats to invertebrates urgently need further assessment but are hard to include in conventional gap analyses). Ferrier’s analysis, which is more easily applied to poorly-known species than standard techniques, concludes that 43 percent of terrestrial species may be unprotected, most of them in tropical environments. The technique is now being expanded to assess the likely impacts of habitat loss and climate change.

Güven Eken, of BirdLife International in the Netherlands, and colleagues advance criteria for the identification of key biodiversity areas (KBAs) for fine-scale gap analysis. KBAs are areas large enough (or sufficiently interconnected) to support viable populations of species that are globally threatened. Alternatively, they may hold a significant proportion of the population of species uncommon elsewhere. KBAs are relatively simple to identify and have potential as “a global conservation currency.”

The last article of the Special Section, by Aaron G. Bruner of Conservation International with Raymond E. Gullison and Andrew Balmford, evaluates the expected cost of effectively managing all existing protected areas in developing countries, as well as the cost of their expansion into high-priority new areas. The authors estimate that costs of establishing and managing an expanded protected-area system would total at least $4 billion per year over the next decade, an amount that “far exceeds current spending but is well within the reach of the international community.” The findings indicate “the need for rapid action to mobilize significant new resources for the developing world’s protected areas.”