Thursday, February 17, 2005

Earth's Hotspots

Hotspots Posted by Hello

The blogosphere is all abuzz with continuing revelations about Jeff Gannon's hotspots, his backdoor entre into the White House, and his partisan hackery questions that finally caused everyone to prick up their ears. And while I do desperately hope this controversy will stick to our President with tenacious ferocity, there are other things happening on our planet still worthy of our attention.

WITH the world facing an unprecedented mass extinction of species, conservationists trying to stem the loss are still struggling to answer some basic questions. Where do most of the world's plants and animals live? And where should we spend our time and money if we are to save as many species as possible?

For many conservation groups, the answer is to focus on so-called biodiversity hotspots - areas where the greatest number of species are under imminent threat. This week, the leading proponents of this approach have published an updated classification of the world's hotspots that will set their conservation priorities for years. But even as they do so, others are saying that the whole idea of hotspots should be discarded.

The hotspot approach was proposed in 1988 by ecologist Norman Myers. To qualify as a hotspot, Myers argued, a region must meet two criteria: it must contain a large number of species that are found nowhere else on Earth, and it must be under threat from human activity.

This makes intuitive sense. Such localised species, known as endemics, tend to be the ones in greatest need of protection. "If we lose them, we can't find them anywhere else. We don't have any other place we can go and save them," points out Michael Hoffmann, a biodiversity analyst for Conservation International, based in Washington DC.

These revisions bring the number of hotspots worldwide to 34. They occupy just 2.3 per cent of the Earth's land surface, yet are the sole home for 50 per cent of vascular plant species and 42 per cent of land vertebrates. "These are the places we need to go first," Hoffmann says.

But some conservationists dispute the value of hotspots. One problem is that they don't provide fine enough resolution, says Eric Dinerstein, chief scientist at the World Wildlife Fund (WWF) in the US. A more useful analysis would be to do away with the broad-brush hotspots approach and focus on smaller ecoregions. WWF has identified 867 of these regions worldwide.

The finer scale of such an analysis can reveal interesting patterns. In an analysis of 140 Indo-Pacific ecoregions published last year, for example, those with the highest proportion of endemics turned out to be islands and mountain tops, which offer a relatively isolated setting in which new species have been able to evolve An "islands and highlands" emphasis should pay conservation dividends, says John Fa, director of conservation at the Durrell Wildlife Conservation Trust in Jersey, Channel Islands, who led the research. "They are easier to protect, because they are smaller areas," he notes. "It's much easier than saving an Amazon basin or a Congo basin." He is quick to point out, however, that these large tracts of wilderness also deserve protection in their own right.

According to Fa and other critics, the hotspots approach focuses too much on the number of endemic species. The species-rich tropics and subtropics get most attention, while less diverse, but no less distinctive, Arctic and temperate regions are overlooked. We should target ecoregions with a high proportion of endemics, he says, even if the absolute number of species is relatively small.

Even hotspot proponents accept that not all our conservation effort should go toward hotspots. "Nobody is saying we should give up on the Serengeti, for instance, which is not in a hotspot," Hoffmann says. "All we are saying is that these are the top, urgent priorities."

In the end, whether hotspots are helpful or not may depend on whether you think it more important to save the largest number of species or the most representative cross-section of the world's biodiversity. "Individual conservation organisations should decide what matters to them. We shouldn't expect them to agree," says David Wilcove, a conservation biologist at Princeton University.

"The fact they have different priorities is not necessarily a bad thing. There are clearly different values out there, and we ought to be respectful of that diversity in the same way we are respectful of the diversity of life on Earth."

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