Tuesday, August 16, 2011

Lessons from the world's longest study of rainforest fragments

August 15, 2011
Source: mongabay.com

Forest fragments under research in the Biological Dynamics of Forest Fragments Project. Photo by: Richard Bierregaard.

For over 30 years, hundreds of scientists have scoured eleven forest fragments in the Amazon seeking answers to big questions: how do forest fragments' species and microclimate differ from their intact relatives? Will rainforest fragments provide a safe haven for imperiled species or are they last stand for the living dead? Should conservation focus on saving forest fragments or is it more important to focus the fight on big tropical landscapes? Are forest fragments capable of regrowth and expansion? Can a forest—once cut-off—heal itself? Such questions are increasingly important as forest fragments—patches of forest that are separated from larger forest landscapes due to expanding agriculture, pasture, or fire—increase worldwide along with the human footprint.

The Biological Dynamics of Forest Fragments Project (BDFFP)—begun in 1979—has started to provide general answers to these questions. As the world's longest-running and largest study of forest fragments in the world, it has more than any other area given tropical ecologists' a sense of how forest fragments, both big and small, function. Located fifty miles (80 kilometers) north of Manaus, Brazil, the study encompasses eleven fragments, spanning from 1 hectare to 100 hectares.

"The study is very ambitious in scope, covering just about every major group of organisms. We've studied everything from trees to tamarins, and army ants to antbirds," says Dr. William F. Laurance, an ecologist at James Cook University, in a recent interview with mongabay.com. His colleague Dr. Thomas Lovejoy, biodiversity chair at the Washington DC-based Heinz Center for Science, Economics and the Environment, adds that in 32 years the research area has produced an astounding 581 publications.

Studies in the region have made clear delineations between forest fragments winners (for example some rodents and light-loving butterflies) and losers (mammals with big ranges and certain birds), have documented loss of carbon due to mortality of big trees, and have shown that no fragment is the same—size makes all the difference and fragments are constantly changing due to age or events such as droughts and windstorms.

"In many ways we're still scratching the surface. We know very little about how fragmentation affects key ecological interactions among species. And many changes are likely to take a long time to become manifest, such as changes in the community composition of trees, some of which can live for a millennium or longer. Further, we have only a rudimentary idea of how fragmentation will affect species that live up in the forest canopy, or below ground in the soil," Laurance says.

Research from the BDFFP has proven important for conservation decisions, says Lovejoy.

"One of the interesting things is the very existence of the project influenced the size of protected areas being created. And protected areas have tended to be even larger in recent years."

In an age of climate change and mass extinction, forest fragments—even though they are inherently degraded—are vital conservation pieces. Many of the world's great tropical forests, such as the Atlantic Forest of coastal Brazil and the Western Ghats of India, almost solely survive in fragments.

While forest fragments may never be returned to their original state, the BDFFP project has found hope that forests may be 'bandaged'. In other words, improvements on their management, including corridors between forests, may see a rise in biodiversity and ecosystem services. Sometimes, says Lovejoy, human restoration can make a big difference.

"The biggest problem is that many of the forest canopy tree species have very large seeds that require a rodent to disperse them. So the bigger the area the more slowly the forest succession takes place. This can be hastened by actual planting of trees as was done in the 19th century for the Tijuca Forest in Rio de Janeiro—now the largest urban forest in the world."

In an August 2011 interview William Laurance and Thomas Lovejoy discuss the milestones from the world's longest study of tropical forest fragments, how forest fragments in the Amazon function, and the place of forest fragments in conservation efforts worldwide.

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