Scientists reveal true scale of Amazon logging

Despite efforts to promote sustainable forests in the Amazon, thousands of acres are still being felled illegally. Picture / Reuters

The Amazon rainforest is being destroyed twice as quickly as previously estimated, according to a satellite survey of the region.

A team of American and Brazilian specialists have been able to assess the damage done by "selective logging", when one or two trees are removed, leaving surrounding trees intact.

They found that selective logging of mahogany and other valuable hardwood trees, which is often illegal, is destroying an area equal to that razed by conventional logging.

Study leader Dr Gregory Asner said the new satellite technique had provided a shocking insight into the true scale of destruction.

Conventional satellite images showed that an area of about 9334 sq km of the rainforest is burnt or cleared each year to make way for cattle ranching, farming or other development. However, scientists using the new technique found that selective logging damage was comparable in area.

The volume of carbon released into the atmosphere as a result of selective logging between 1999 and 2002 is estimated between about 10 million and 15 million tonnes.

This represents a 25 per cent increase in the overall flow of carbon from the Amazonian forests into the atmosphere.

Studies of area subjected to selective logging show light penetrates to the understorey and dries out the forest floor, making it vulnerable to fires. Selective logging also involves heavy equipment being used to create makeshift dirt roads, allowing more people to come in later and change the landscape further, fuelling the process of deforestation.

The satellite technique developed by the scientists at Stanford University and the Carnegie Institution allows the scientists to peer through the dense forest canopy to find out what is happening underneath.

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