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Logging poses a serious threat to thelowland forests on Borneo Island that are home to orangutans. |
Some experts say drawing up a global "Red List" of vanishing ecosystems would help them spot looming crises caused by climate change, cutting of forests and many other problems. The list also would sharpen the focus on areas that should be handled as conservation priorities.
Along the shore of Venezuela's Lake Maracaibo, runoff filled with sediment and pesticides has been smothering animals that once lived among the roots of the mangrove trees, including crabs, fish hatchlings and shellfish, said Luz Esther Sanchez, a marine biologist and ecologist. She has been studying such dead zones and says saving the mangroves requires a comprehensive effort to reduce water pollution and halt the clearing of other forests upstream.
"Declaring the mangrove ecosystem threatened would be very useful for conservation," Sanchez said.
"People stand up to defend dolphins. People stand up to defend turtles. But I've never seen them defend the mangrove forest with the same vehemence."
An international working group of biologists and conservation experts has been developing a system for classifying threats to ecosystems, and in October presented an initial blueprint at a UN conference on biodiversity in Nagoya, Japan."If we can get a good, rigorous scientific system in place that is relatively easy to monitor worldwide, ... you can follow these changes and describe them and ring the alarm bell where things might go wrong," said Dutch conservation expert Piet Wit.
He chairs the Commission of Ecosystem Management of the International Union for Conservation of Nature, or IUCN, which maintains the Red List of thousands of threatened plants and animals that is the international standard.
Some scientists caution that agreeing on precise categories to divide up habitats would be a monumental task. But many already agree on some ecosystems that are threatened or endangered, including many coral reefs, salt marshes, mountain habitats threatened by rising global temperatures, grasslands in southern Russia and Brazil's Atlantic forest.
Logging poses a serious threat to the lowland forests on Indonesia's Borneo Island that are home to endangered orangutans. In the Andes, expanding farmland has fragmented the cloud forests where spectacled bears live.
"You usually get ecosystem decline occurring first, and then species decline later on," said Jon Paul Rodriguez, a Venezuelan conservation biologist who is leading the IUCN working group.
"The ecosystem Red List would identify places for preventative conservation," said Rodriguez, who joined 20 other experts in laying out proposals in a November article published online by the journal Conservation Biology.
The list of habitats devastated by people has been growing. The once-vast Aral Sea between the former Soviet republics of Kazakhstan and Uzbekistan shrank by about 90 percent due to diversions of water, leaving behind a salty wasteland and abandoned fishing boats, and ruining the local economy. North American tall grass prairies have largely vanished along with the game animals that once thrived in them. Some rivers such as the Rio Grande have been strangled by heavy pumping and now barely reach the sea.
Some experts point to Easter Island as a particularly catastrophic ecosystem collapse. Centuries ago, the South Pacific island's inhabitants erected the giant head-shaped stone statues known as Moais. They cut down the island's forests, and some researchers have concluded that the destruction of the island's fragile environment probably contributed to the civilisation's collapse.
Today, some efforts to save threatened species appear to be working. Humpback whales, for instance, have rebounded from "vulnerable" to being at low risk of extinction due to the international ban on commercial whaling. Strict regulations have permitted the recovery of some types of fish that once were heavily overfished, such as striped bass along the U.S. mid-Atlantic coast.
One study released last month during the UN conference in Japan found that efforts to save endangered animals are making a difference. The report found that dozens of threatened species on the Red List have seen improvements in their status, and concluded that the overall march toward extinction would have been about 20 percent faster if no conservation steps had been taken.
"Species Red Lists have already been a huge policy success, so there's reason to think that ecosystem Red Lists could be too, and could complement them," said Kathryn Rodriguez-Clark, an ecology and conservation specialist at the Venezuelan Institute of Scientific Research who is part of the IUCN effort.
Scientists and environmentalists have previously come up with their own systems for targeting habitats in danger of disappearing. Researchers in South Africa, Australia and Venezuela have begun to list and map out threatened ecosystems. The World Wildlife Fund has a list of biologically rich "ecoregions" that it uses in prioritising areas to protect.
The new effort aims to come up with a uniform, standard system of classifying habitats. Rodriguez said such a system could help identify new conservation goals, drawing on data from satellite images.
"When you take a view that is big-scale, you may end up finding things that were not on people's radar screens," said Rodriguez, a researcher at the Venezuelan Institute of Scientific Research.
Stuart Pimm, a Duke University professor and expert on preventing species extinction, called the effort a good idea but said he is sceptical about how it can be put into practice.
"It's much, much more difficult to define an ecosystem than it is to define a species," Pimm said. "And the more finely you define things, the more tricky it's going to be."
Pimm said he is concerned it would be difficult to come up with "a consistent set of definitions that will survive political pressure" and hold up when tough environmental management decisions need to be made.
The researchers promoting a global list of ecosystems are aiming for the proposal to be formally adopted by IUCN in 2012. Next would come the process of agreeing on lists and mapping out threatened places.
John Benson, a senior plant ecologist at the Botanic Gardens Trust in Sydney, Australia, who is part of the effort, has spent 11 years developing a system for classifying and assessing threats to types of vegetation in his home state of New South Wales.
He said even in poor countries that would not be prepared to adopt new regulations aimed at protecting habitats, endangered ecosystem lists could be used to "raise the profile of types of ecosystems for directing effort and funds toward protecting them."
In the case of Venezuela's coastal mangroves, Sanchez said that species-specific conservation measures are insufficient because the habitat is being degraded by muddy water that comes down streams and rivers from areas where mountain forests have been felled. She said runoff filled with pesticides is also likely taking a toll, and that in some parts of western Venezuela - which is dotted with oil rigs - leaks from oil pipelines have done damage.
"If the watershed isn't protected ... it's inevitably going to die, which is what's happening," she said. "It's all connected."