SE Asian species dying at epic rate

Up to one-fifth of the world's plant and animal species could be wiped out within 100 years by deforestation in southeast Asia, according to a survey of extinction rates in Singapore in this week's Nature.

This bleak prognosis calls for tough conservation measures, says Barry Brook of the Northern Territory University in Darwin, Australia, who led the study. "If we don't do anything, things will unfold in a very unpleasant way," he says.

Tropical rainforests contain a huge and valuable variety of plants and animals. But the encroachment of humans, through deforestation and urbanisation, can create homogenised ecosystems, in which only a fraction of species survives, Brook says.

Singapore is a case in point. Since British colonisation in 1819, the habitats of terrestrial and freshwater species have shrunk by more than 95%. Brook's team calculates that this has caused the extinction of up to 87% of the island's butterflies, fish, birds and mammals.

Many of those that remain are too scarce to recover. Such "living dead" species are effectively condemned to extinction, Brook's team reports.

The researchers used data stretching back to 1870 to estimate the impact of human activity on Singapore's flora and fauna. They conclude that most species met their demise through habitat destruction, although some larger animals were wiped out by hunting. Singapore's last tiger, for example, was shot in 1930.

Unless conservation efforts are in creased, Singapore's neighbours could inflict similar damage, Brook warns. Malaysia has already lost 60% of its rainforests, he points out.

"This study confirms that we have a very urgent problem," agrees Andrew Balmford, who studies conservation strategies at the University of Cambridge. "Species richness is more sensitive to habitat loss than was previously thought."