for National Geographic News
Damage to the Amazon rain forest has been underestimated by half, according to new high-resolution satellite images, which have revealed long-hidden logging activities.
Scientists say a new satellite imaging system that can penetrate the rain forest canopy shows that "selective logging," the singling out and cutting of commercially prized trees, poses a far bigger threat to the Earth's largest tropical forest than previously thought.
Writing in tomorrow's issue of the journal Science, researchers warn that their study has far-reaching implications for rain forests worldwide.
Lead author Greg Asner, an ecologist at the Carnegie Institution's Department of Global Ecology in Palo Alto, California, says that for decades loggers have been targeting and extracting high-value trees one by one, with the rain forest canopy covering their tracks.
"We discovered that annually an area the size of Connecticut is disturbed this way," he said. "Timber harvests are much more widespread than previously thought."
Until now satellite-based forest monitoring was unable to penetrate the upper layers of forest leaves, only detecting swathes cleared either for farmland or by major logging operations.
The new technology, developed by Carnegie scientists, allowed researchers to pinpoint very small areas of deforestation using large-scale, high-resolution images.
The system was used to detect selective logging in the top five timber-producing states of the Brazilian Amazon between 1999 and 2002.
Affected areas ranged from 4,660 to 7,650 square miles (12,070 to 19,820 square kilometers) each year, where between 953 million and 1.8 billion cubic feet (27 and 50 million cubic meters) of timber was removed annually.
The authors say this represents a 60 to 123 percent increase on previously reported damage to the Amazon forest during the four-year study period.
"We expected to see large areas of logging. But the extent to which logging penetrates deep into the frontier is much more dramatic than we anticipated," said co-author Michael Keller of the U.S. Forest Service.
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