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WORLDWIDE FOREST/BIODIVERSITY CAMPAIGN NEWS

Forest Fragmentation May Worsen Global Warming

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Forest Networking a Project of Ecological Enterprises

http://forests.org/

1/10/98

OVERVIEW, SOURCE & COMMENTARY by EE

The following press release describes a substantial loss of biomass in

Amazonian rainforest fragments, and follows from a recent article in

the journal Science. Die-back of trees near forest edges is believed

to be a significant source of carbon into the atmosphere. I have some

further thoughts on the matter. Fragmented forest landscapes are

frequently composed of remnant forests too small to be viable and are

thus in decline. Management of any particular forest patch requires

maintenance of the larger-scale ecological context. Ultimately,

forest ecosystem stability depends upon large, connected and intact

ecological cores surrounded by various intensities of managed forest

buffers. Evidence would indicate that 40-60% of the forest matrix

must be composed of late-successional forest set-asides in order to

maintain the ecological integrity and regenerative capacity of the

larger forest ecosystem. The following item was relayed by a list

recipient--please everyone, chip in some information when you can.

And visit http://forests.org/web/ to comment on these items.

g.b.

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RELAYED TEXT STARTS HERE:

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).

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