CORVALLIS, Ore. The Biscuit Fire of 2002 burned more severely in areas that had been salvage logged and replanted, compared to similar areas that were also burned in a 1987 fire but had been left to regenerate naturally, a new Oregon State University Study concludes.
The analysis, one of the first to ever quantify the effect of salvage logging and replanting on future fire severity, is being published this week in Proceedings of the National Academy of Sciences, a professional journal.
It found that fire severity was 16 to 61 percent higher in logged and planted areas, compared to those that had burned severely and were left alone in a fire 15 years earlier. The study was done in areas that had burned twice once in the 1987 Silver Fire, and again in the massive 2002 Biscuit Fire, one of the largest forest fires in modern U.S. history.
Many forest managers in the past have assumed that salvage logging after a severe forest fire, along with replanting new trees, will reduce future fire severity, said Jonathan Thompson, a doctoral student at OSU in the Department of Forest Science, and lead author on the study. This is based on the assumption that removing dead trees reduces fuel loads and planting conifers hastens the return of fire resistant forests.
However, those assumptions have never really been tested, Thompson said. This analysis showed that, after accounting for the effects of topography, Silver Fire severity and other environmental variables, the Biscuit Fire severity was higher where they had done salvage logging and planting.
Its not completely clear from these data, Thompson said, what the causative mechanism is the tree removal, the addition of more fine fuels to the forest floor during the logging operation, or the growth of new trees that for several decades may be very vulnerable to new fires.
The study is not, researchers said, an indictment of salvage logging it may still have value f
Contact: Jonathan Thompson
Oregon State University