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Scientists find ecosystems more valuable if left alone

Friday, August 09, 2002

By Wallace Chuma, Post-Gazette Staff Writer

The world loses up to $250 billion every year from the destruction and conversion of natural ecosystems for human uses, according to an analysis by an international group of scientists published in today's issue of the journal Science.

The scientists, including Stephen Farber of the University of Pittsburgh Graduate School of Public and International Affairs, said untouched areas provide economic benefits, such as flood protection or tourism, that are lost when those areas are cleared for economic development.

Too often, the economic benefits of ecosystem conversion, such as clearing tropical forests for agricultural plantations, or dynamiting coral reefs for fishing, are far less than the natural ecosystem provided, they said.

Participants in the research project, organized by the Royal Society of Birds in England, included economists, biologists, botanists and zoologists. The findings will be presented at the World Conference on Sustainable Development that begins late this month in Johannesburg, South Africa.

Farber, who worked with three Pitt graduate students to find studies around the world that compared the economic and social impacts of intact and converted ecosystems, said natural ecosystems are often converted to immediate human use without considering the benefits of leaving some of the areas intact.

He cited the case of Honduras, where a hill slope was cleared for the construction of hundreds of houses. But the clearing left the hill side prone to flooding and the houses subsequently were destroyed by mud slides.

If natural ecosystems were to be preserved, Farber and his colleagues argued in the Science article, they would attract more value in economic terms than when they are converted.

The benefit-to-cost ratio is more than 100 to 1 in favor of conservation, they contended.

The research team, headed by Andrew Balmford of the University of Cambridge, analyzed five different case studies of converted ecosystems: the conversion of a Malaysian tropical forest by intensive logging, a tropical forest in Cameroon converted to small-scale agriculture and commercial plantations, a mangrove system in Thailand converted for shrimp farming, a Canadian marsh drained for agriculture and a Philippine coral reef dynamited for fishing.

Lester Lave, an economist at Carnegie Mellon University, questioned whether the researchers may have overgeneralized, basing their findings on only a limited number of studies.

"The researchers only gave five examples, yet they generalize based on these case studies," he said.

Lave also said the report failed to identify the economic, as distinct from aesthetic, values in preserving nature without major development.

"There are still many places [with natural ecosystems] in the U.S. and old grown forests with trees untouched in Europe. The report should have told us the distinct values of these, in economic terms," he said.

"It's clear that in the name of economic development we do crazy things, like cutting down equatorial forests, but that has been looked at before," Lave said. "We don't need any deep economic analysis to tell us that."

Wallace Chuma can be reached at wchuma@post-gazette.com or 412-263-1601.

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