Can new growth save the Amazon rainforest?

Vegetation is reclaiming agricultural land and might save us from consequences of deforestation

Published August 17, 2009 10:05AM (EDT)

Felipe Garcia's shack backs up against a wall of forest. "My neighbors abandoned their farm seven years ago," says Garcia, a farmer. "Now the jungle has taken over their property once again." He strokes his round belly and says: "And if I don't till my field, it'll look the same way in a few years."

Garcia is a member of the Ngöbe tribe, the largest indigenous group in Panama. He is one of the few residents of the small town of Chilibre who still make a living farming. Most of the local farmers abandoned their farms long ago. "Farming is too hard work for the young people," Garcia complains. "They prefer to work in the capital."

Panama City's office buildings are about an hour's drive away. Chilibre has become a bedroom community as residents choose to commute to the capital. It has also become a field laboratory for botanists and ecologists fascinated by the dense vegetation that has returned to abandoned farms in the former Canal Zone within just a few years.

Undervalued growth
In the past, scientists scorned the "secondary forests," as the new growth is called. There is no doubt that they are not nearly as spectacular as the species-rich primary forests, with their giant trees, which are often centuries old; and they are not home to nearly as many animal and plant species. But now a growing number of biologists are interested in this previously ignored vegetation. According to a United Nations study, the ecological importance of these new forests, which are "growing dramatically" all over the world, is "undervalued."

Is the rain forest truly recovering from overexploitation? And could it be that the consequences of deforestation are not as devastating as environmentalists have been preaching for years?

"There are more secondary than primary rain forests in most tropical countries today," explains American biologist Joe Wright. "On the whole, the amount of land covered by vegetation is stable." In tropical countries, in particular, rural flight and urbanization have led to more and more farmers abandoning their fields, allowing new vegetation to grow rampant on the fallow ground. "The numbers speak for themselves," Wright says.

Wright is a research biologist at the Smithsonian Tropical Research Institute in Panama. He works in a wooden building built by the Americans in the former Canal Zone, just a few kilometers from Felipe Garcia's hut. He has spent the last 25 years studying Central American jungles, which have long consisted primarily of secondary vegetation. "Even the Mayans were cutting down forests," Wright says.

Naive claims
Wright recently investigated areas that were cleared to build the Panama Canal, where the Americans displaced local settlers. Since then, much of the region has reverted to rain forest. To a layman, it is hard to recognize the difference between primary and secondary forest. In the Canal Zone's newer forest, monkeys screech, colorful butterflies flutter across jungle paths, and an eagle circles overhead. According to Wright, "many animals adapt to the environment, and 80 percent of biodiversity is preserved."

With his field studies, Wright has triggered a scholarly dispute among scientists around the world. "Joe is naive," says Bill Laurance, who conducted research in the Brazilian Amazon region for many years and even works at the same institute as Wright. Privately the two men are friends, but professionally they are bitter rivals.

Laurance fears that Wright is downplaying the destruction of virgin rain forest. "The conditions in the small country of Panama cannot be generalized. In the Amazon, cattle ranchers and the agricultural industry are destroying the jungle on a large scale. The undergrowth that thrives in cleared areas is a caricature of a forest."

Even Wright concedes that Brazil is a key region for the future of the rain forest. Three-quarters of the Amazon jungle lie in Brazilian territory. Nowhere else is the forest being destroyed so recklessly. Nevertheless, there is a lack of reliable information about the long-term consequences of overexploitation.

Looking under the mask
Brazil's National Institute for Space Research (INPE), which monitors the jungle via satellite, reports that 17 percent of the Brazilian Amazon rain forest has been deforested. But what happens in cleared areas when they are abandoned after years of agricultural use remains a big mystery, says INPE researcher Claudio Almeida.

In Belem, in the Amazon delta region, the Brazilian scientist is currently setting up an INPE institute devoted to the study of rain forests. In his office, littered with moving boxes and electronic equipment, Almeida is sitting at a computer, analyzing satellite images transmitted by the INPE satellite-monitoring center in São Paulo. The images from space depict only recently cleared areas of land. So far scientists have not looked at the question of how areas that were deforested some time ago have changed in the meantime. "We are now looking under the mask for the first time," says Almeida.

The São Paulo agronomist is studying secondary vegetation throughout the entire Brazilian Amazon region. Using satellite images, he selected 26 locations that were cleared years ago and eventually became overgrown with new vegetation. Then he spent two months driving from one location to the next. His conclusion? "Twenty percent of the deforested areas are recovering."

Nevertheless, Almeida is not issuing a general all-clear signal for the rain forest. "Within no more than five years, most of the secondary forests will be burned down or cut down again," he says. Cattle ranchers use the fallow fields as pasture, while farmers plant soybeans or cereal crops.

Nevertheless, the secondary vegetation provides Brazil with a significant benefit. The new forests help capture carbon dioxide, a greenhouse gas, thereby curbing global warming. "We have more biomass than was previously believed," says Almeida. The new forests will be a central issue at the U.N. Climate Change Conference in Copenhagen in December, where the successor to the Kyoto Protocol is to be discussed.

Wright, for his part, would like to see secondary forests placed under protection right away. "In many countries, there isn't any old-growth vegetation left. We have to protect what's left to protect."

Translated from the German by Christopher Sultan.

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By Jens Glüsing

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