Satellites Show Central African Forests Disappearing Due to Logging

Tree felling in the Congolaise Industrielle des Bois
[Image courtesy of Nadine Laporte, WHRC]

Using NASA satellite images, scientists have documented a sharp expansion in logging roads in the tropical forests of Central Africa. They describe these findings in the 8 June issue of Science.

With an estimated 30 percent (more than 600,000 square kilometers) of the Central African forest apportioned for logging and just 12 percent protected by conservation laws, scientists are worried that logging companies will disturb an environment considered among the most unspoiled.

"Central Africa's dense humid forests have long been regarded as among the most pristine on Earth," wrote lead author Nadine Laporte, a researcher at the Woods Hole Research Center in Falmouth, Mass. "But in recent decades, industrial logging has become the most extensive form of land use in the region."

In their Brevium, Laporte and colleagues analyzed more than 300 Landsat satellite images, covering 4 million square kilometers, to track the progression of logging roads for three decades preceding 2003.

The team mapped 51,916 kilometers of logging roads within the survey area—a number the researchers believe is conservative because of satellite image quality and the frequency of logging roads conversion into public roads where the population is dense.

The highest logging road densities were in Cameroon and Equatorial Guinea, and the most rapidly changing area was in northern Republic of Congo, where the rate of road construction has roughly quadrupled over this time period.

The researchers also estimated that logging roads account for 38 percent of all roads in the surveyed area, and more than 60 percent in the Democratic Republic of Congo and the Republic of Congo.

With the exception of the Okoumé forests of Gabon, most of the industrial logging is selective and focused on high-value tree species for export, such as African mahoganies, according to the authors.

While laws are in place to protect the forests, the authors suggest limited domestic resources and a drastic increase in foreign investment in logging land grants prevent effective enforcement of the conservation regulations.

In addition to raising awareness of the loss of Central African forests, the authors believe that their research demonstrates the utility of using satellites to monitor deforestation as it "provides a consistent approach to monitor both legal and illegal" logging activities.

Kathy Wren and Benjamin Somers

11 June 2007