THE logging industry has had its fingers burned. Turning dead trees into logs after forest fires seems to exacerbate forest damage in any subsequent fires.
鈥淔or a long time there was a perception that by salvage-logging fire-killed trees, you would be removing a lot of potential fuel for future fires,鈥� says Jonathan Thompson of Oregon State University in Corvallis. The logging industry is keen on salvage logging because commercially valuable trees such as conifers can be planted (快猫短视频, 5 August 2006, p 4).
Thompson and colleagues studied before and after satellite images of two large fires in south-west Oregon. The 2002 Biscuit fire engulfed more than 200,000 hectares, over 18,000 of which had already been burned in the 1987 Silver fire. In the three years after the Silver fire, more than 800 hectares were logged to salvage any wood that could be sold, and the land was replanted with conifers. The team discovered that areas logged for salvage burned between 16 and 61 per cent more severely during a second fire than areas left to regrow naturally (Proceedings of the National Academy of Sciences, vol 104, p 10743).
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鈥淎reas logged for salvage burned 16 to 60 per cent more severely in a second fire鈥�
Thompson now says this type of forest management should not be used in an attempt to limit the risk of future fires, although he says it may still have economic value. The satellite data wasn鈥檛 detailed enough to allow the team to determine whether it was the logging or the replanting that made the second fire worse in certain areas. Salvage-logging operations can leave a lot of the higher branches on the ground, where they can fuel future fires, says Thompson, but it is difficult to say how much of an effect this would have had 15 years later.
He says it is more likely that the conifers which replaced the original forest provided a homogenous fuel for the 2002 fire, causing replanted areas to burn more fiercely.
