Title:    Forest Fragmentation May Worsen Global Warming 
Source:   Bill Laurance
Status:   Distribute and reprint freely
Date:     Monday, January 5, 1998

Scientists working in the Amazon Basin have discovered that the creation of isolated fragments of rainforest--a common aftermath of land development--may contribute to global warming.

This occurs, they say, because fragments of rainforest experience a striking die-off of trees. As the trees decompose, they release carbon dioxide, methane and other greenhouse gases which are known causes of global warming.

"Our early estimates suggest greenhouse gas emissions from fragmentation of tropical forests are considerable--the equivalent of clearing and burning up to three million acres of rainforest each year," said Dr William Laurance, leader of the joint U.S.-Brazilian research team which reported their findings this week in the journal Science (vol. 278, pp. 1117-1118).

The die-off occurs because trees in isolated patches are easily knocked down during windstorms, and are also vulnerable to hot, dry winds which blow in from surrounding fields or pastures. "Many rainforest trees are really sensitive to being dried out," said Dr Laurance. "If that happens they often just drop their leaves and die."

Scientists on the research team, from the Smithsonian Institution and Brazil's National Institute for Research in the Amazon, are now trying to improve their estimates of greenhouse gas emissions.

"We've known for years that fragmentation drastically alters the ecology of rainforests, and threatens the survival of thousands of plant and animal species," said Leandro Ferreira, a Brazilian team- member. "But now we see it's probably affecting the global climate as well."

Dr Laurance emphasized that forest fragments were only one of several sources of greenhouse gas emissions. Most emissions are caused by the burning of fossil fuels, and by the rapid destruction of tropical forests. Worldwide, about 40 million acres of tropical forest are being cleared and burned each year.

"The big point of this work is that it shows we all share a stake in the preservation of tropical forests," said Dr Laurance. "Rich nations like the U.S., Europe and Japan are going to have to help developing countries--which contain almost all of the world's tropical forest--with the financial burdens of forest conservation."

Further inquiries can be directed to Dr William Laurance, National Institute for Research in the Amazon, Manaus, Brazil (phone: 55-92- 642-1148; fax: 55-92-642-2050; email: wfl@inpa.gov.br).