Ecology

Tropical Tree Communities

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Science  14 Jan 2000:
Vol. 287, Issue 5451, pp. 193
DOI: 10.1126/science.287.5451.193b

Conservation of biodiversity depends on, among other things, a knowledge of the distribution and abundance of the target organisms. For many large organisms of the temperate zone we have reasonably accurate distribution maps, but for tropical trees there are few, if any, species that have been mapped at the scale that matters—that of the sustainable population. Pitman and colleagues present the results of a survey of more than 800 tree species in the western Amazonian forests of the Manu National Park, Peru, using a network of forest plots of various sizes distributed over a total area of 400 km2. They show that most species are, not surprisingly, rare in most locations, but the data are sufficiently detailed to reveal different forms of rarity.

Building on a scheme developed in the 1980s by Deborah Rabinowitz, Pitman et al. classify tree species according to their habitat specificity, geographic range, and local and regional population size. They find that most species are extensively distributed across western Amazonia and grow in a range of different forest types. At large spatial scales, such species can therefore be abundant. Fewer than 20% of species are restricted to a small number of forest types, and none of the species is endemic to the Manu park (i.e., not found elsewhere). Reassuring as this picture might seem for the conservation of lowland tropical forest trees, these results in fact underscore the need for the protection of very large areas of forest if viable populations are to be maintained.—AMS

Ecology80, 2651 (1999).

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