Selective logging leads to clear-cutting in the Amazon rainforest
mongabay.com
July 31, 2006


A new study links selective logging to clear-cutting in the Amazon rainforest. The research is significant because it identifies "an important indicator of rain forest vulnerability to clear-cutting in Brazil."


Deforestation in the Amazon rainforest of Peru. Photos by Rhett A. Butler.
A team of scientists, led by Greg Asner of the Carnegie Institution's Department of Global Ecology at Stanford University, found that 16% of selectively logged rainforests were completely cleared within one year and 32% were totally deforested within four years. The researchers also found high correlation between the presence of roads and deforestation, with virtually no selective logging occurring at distances greater than 15 miles from roads.

The findings, published in the July 31, 2006 online early edition of The Proceedings of the National Academy of Sciences (PNAS), come shortly after Brazil announced plans to open up large areas of the Amazon to selective logging. The sustainable logging initiative, which includes the development of a remote sensing system by the Brazilian National Space Research Institute (INPE) and the Brazilian non-governmental organization IMAZON to monitor timber-cutting in the region, could benefit from the latest Carnegie Institution results, say the authors of the study.

The scientists combined high-resolution, remote-sensing techniques with deforestation maps provided by the Brazilian government to measure logging over a 5-year period across an area of 17,760 square miles (46,000 sq km) in four states. The researchers found "that the probability that logged areas will be clear-cut is highly dependent on their distance from major roads," according to a news release from the Carnegie Institution. "Most of the selective logging is concentrated within 3 miles (5 km) of major roads. While there was no cause and effect relationship between selective logging and clear-cutting for forests within 3 miles of roads, between 3 and 15.5 miles (5-25 km) from roads there was a clear relationship: selective logging blazes the trail for deforestation. Areas with selective logging at these distances are 2 to 4 times more likely to be cleared than intact forests. "

"The link between selective logging and clear-cutting is a one-two punch. Once a forest is selectively logged, it is likely on the path to destruction," said Asner.

"The researchers were surprised by the tight relationship between the two land-use activities because different groups are involved—loggers versus ranchers and farmers—and those actors are treated differently by government regulators," according to a statement from Carnegie.

"Asner's group puts to rest another important controversy in the science of the Amazon rain forest," said Daniel Nepstad, a leading Amazon researcher with the Woods Hole Research Center. "First they showed that forest degradation by loggers affects as much forest as clear-cutting for cattle ranching and swidden agriculture. This latest article demonstrates that these two processes are intimately linked—that the thinning begets forest replacement by cattle pastures and swiddens."

The research has significant implications for land-use policy in the Amazon basin. The scientists also found that federally protected reserves were significantly less disturbed than unprotected areas.


Hidden threat? Logging road under the forest canopy in Peru. Photo by Rhett A. Butler.
"This breakthrough has created a novel system to detect and quantify even fine-scale logging damage from satellite images across the vast Amazon," added Lisa Curran of the Yale School of Forestry & Environmental Studies. "Through their analyses, Asner's team uncovered unforeseen synergies of logging, road access, and subsequent deforestation. Their innovative methods have the potential to revolutionize how we monitor logging damage and its effects on land-use worldwide."

"The new Brazilian timber concession laws for federally protected lands could bring more control over both the high levels of forest damage caused by current logging operations and the loss of selectively logged forest to full deforestation," concluded Anser.


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mongabay.com (July 31, 2006).

Selective logging leads to clear-cutting in the Amazon rainforest.

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