Damage to the Amazon rain forest may be twice as large than previously thought due to undetected “selective” logging that opens new areas to farming, U.S. and Brazilian forest experts reported on Thursday.
Conventional methods of analyzing satellite images were capable of spotting only clear-cut swathes of land, where all the trees are removed for farming or grazing. Selective logging means individual trees are picked out of the forest.
Researchers at the Carnegie Institution of Washington used a new method to analyze satellite images and detected selective logging in the five major timber production states of the Brazilian Amazon.
The report, published in the latest issue of the journal Science, showed that the size of the damaged forest, taking into account selective logging, was between 60 percent and 128 percent higher than the officially deforested area between 1999 and 2002.
“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 Michael Keller of the U.S. Forest Service, who helped write the report.
Brazil’s fast-growing agricultural frontier and new road projects in recent years have led to the devastation of areas larger than the U.S. state of New Jersey. More recent official figures suggest a slowing of the destruction in 2005.
In August the government estimated that 3,515 square miles were razed between August 2004 and July 2005, down from 7,229 square miles the year before.
Brazil questions data
The government acknowledged the merit of the study but said it overestimated the extent of selective logging.
“The lumber industry doesn’t have the capacity to process such volumes,” Tasso Azevedo, the Environment Ministry’s forestry director, told Reuters.
“Yet if we apply this study at a large scale in real-time, we may one day be a step ahead of illegal logging,” he said.
“Compared with clear-cutting, selective logging is the lesser of the two evils and not directly to blame for massive deforestation in the Amazon,” said Jose Natalino Silva, of Empresa Brasileira de Pesquisa Agropecuoria-Amazonia Oriental in Paro, Brazil.
“The problem is it opens roads to massive clearing for agriculture,” added Silva, who worked on the report.
Silva added that the report did not question the validity of Brazil’s official deforestation figures produced by its space agency Inpe but added more detail to them.
‘Debris field’
Selective logging, the report said, increased the flow of carbon from the Amazon forest into the atmosphere by 25 percent. It also thins the shady canopy and causes damage to the undergrowth, making forests drier and more flammable.
“When you knock down a tree it causes a lot of damage in the understory,” said Gregory Asner of the Carnegie Institute of Washington in Stanford, Calif., who led the study. “It’s a debris field down there.”
Several sustainable development projects financed by the Brazilian government and international lending agencies promote selective logging. But they limit the type, volume, and age of trees cut down.
“In managed forests, selective logging really only accelerates the natural process of trees dying and falling,” said Judson Ferreira Valentim, senior researcher at Embrapa, the government agriculture research enterprise.
The researchers said they would provide the results of the study to the Brazilian government to help tackle illegal, selective logging.
