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Satellite shows how logging makes forest more flammable 
Excessive logging can make forest fires even more devastating, according to a paper published in this week's Nature magazine. Using data from ESA's ERS-2 satellite, a team of scientists from Germany and Indonesia has concluded that the extensive forest fires in Indonesia in 1997-98 damaged recently-logged land much more seriously than virgin forest or land that had been untouched for many years. "The fires severely damaged the remaining forest, and significantly increased the risk of recurrent fire disasters by leaving huge amounts of dead flammable wood," says Dr Florian Siegert, of Remote Sensing Solutions GmbH.
The team used a technique called difference detection' - essentially comparing details of 'before' and 'after' images looking for changes in the radar signature of the forest below. "Fires destroy plants and foliage, reduce moisture content and open the forest canopy," says Dr Siegert, "which significantly changes the way the forest appears to radar." "Our analysis showed that in the fire area, 24% of the forest had up to half the trees killed, 42% was severely damaged, with up to 80% of the vegetation killed, and the remaining 36% showed total destruction, with vegetation burned off completely and almost all trees dead," says Dr Siegert. The team then compared their fire map with a land-use map, derived from Landsat TM imagery!.
The team found that selective logging directly contributed to the unprecedented extent of the 1998 fires. Many areas burned in the 1982-83 fires did not recover into fire-resistant tropical rain-forest, and burned once again. Similarly, the fire hazard has greatly increased for areas burned in 1998.
"Unless land-use policies are changed to control logging and to introduce
reduced-impact logging techniques, recurrent fires will lead to a complete
loss of Borneo's lowland rainforests," concludes Dr Siegert.
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