Region, not range size, dictates the extinction risk of Amazon plants

Journal Watch Online 6 Jul 09;

Just how many plant species are threatened by land development in the Amazon? Scientists have tried to answer that question, but few have accounted for the location of each plant’s habitat range.

Now, a new study in the Proceedings of the National Academy of Sciences says that extinction risk varies wildly depending on the region – and as a result, fewer species may be in danger than we thought.

Past research suggested that extinction rates of Brazilian Amazon tree species could reach 20 to 33 percent, partly because species with small range sizes might easily be wiped out by local development. To investigate further, the authors of the PNAS study analyzed collection records for more than 40,000 Amazon plant species and compared the locations to areas of predicted habitat loss. They found that while some species with small ranges were indeed at risk, others lived in regions that would probably remain undisturbed.

The net result is that only 5 to 9 percent of the analyzed plant species would be in danger of extinction by 2050, they estimate. Since extinction risk is about 50% higher for plants in Brazil’s rapidly developing Cerrado region, the authors say, conservationists should focus their efforts on that area. – Roberta Kwok

Source: Feeley, K.J. and M.R. Silman. 2009. Extinction risks of Amazonian plant species. Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0900698106