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KUFM / KGPR T. M. Power “Healthy Forests” and Wildfire Control: Accumulating Scientific Evidence Even as the Bush Administration and the U.S. Forest Service push forward with their plans to use timber harvests to improve the “health” of our National Forests and reduce the risk of catastrophic wildfire, scientific evidence accumulates that thinning and logging the forested landscape is likely to increase rather than decrease fire dangers and push forests even further away from their natural ecological conditions. Almost no one disagrees with the idea that vegetation including trees immediately around homes need to be carefully managed to reduce the danger that the landscaping we do around our homes might bring natural wildfire right to our doorsteps. That maintenance of our yards and lots along with the maintenance of our homes themselves is the most effective way of reducing home loss in the face of wildfire. But the Bush Administration and some of the leadership of the Forest Service want to use logging techniques in places far removed from homes and communities to reduce the threat of wildfire. The basic idea is that most of our forests are far too dense. There are way too many trees per acre. This, we are told, not only makes them “unhealthy” but also reduces their productivity for wood production and makes them prone to frequent and severe wildfires that damage the forests even further. Cutting down many or most of those trees is the proposed solution.
But the evidence is mounting that this is not the case. Studies
of actual fire behavior in Some of the fires in 2002 were so huge that they provided a natural laboratory to study what impact previous forest treatments had on how much damage the forest fires did to trees. Despite the usual picture often painted for us of fires simply blackening thousands and thousands of acres, totally destroying all the trees and every other living thing, forest fires actually have very diverse impacts, usually creating a mosaic of heavily burned as well as relatively lightly burned landscapes. By studying the variation in tree mortality in these large fires and matching that up with previous human manipulation of those forestlands, the scientists could get a picture of what, for instance, previous thinning did to control the severity of the damage done by the fires. What they found in both Oregon’s Biscuit Fire and Colorado’s Hayman Fire was that areas that had not been thinned or subject to prescribed burns before the recent fire lost about half of their trees in that fire. In areas that had been thinned, 80 to 100 percent of the trees were killed. Thinning the forests made them more vulnerable to wildfire. This was not entirely surprising to the scientists. Thinning the forest opens the forest up to more sunlight and wind. That increases the temperature and lowers the humidity, drying out the forest more and allowing the higher winds to carry any fire that starts further and hotter. In addition, the thinning activity disturbs the ground, baring mineral soil for a new crop of shade intolerant young trees, shrubs, and invasive weeds. In addition, the thinning typically leaves behind much of the harvested trees: Limbs with needles and small non-marketable trees litter the ground with fuels. When wildfire hits, it has all of the components to be a very hot fire with plenty of ladder fuels to kill almost all of the trees. That is not an inevitable outcome. But avoiding that outcome would be very costly. For instance, the studies show that thinning is not a permanent solution to an overly dense forest. Opening the forest up just triggers the growth of new seedlings and other vegetation. Unless the forest is entered on a regular basis, every decade, say, the thinning will simply have recreated the problem it sought to cure. But such regular and repeated thinning would be outrageously expensive. An alternative is to following the thinning with a prescribed burn. In the Biscuit Fire, areas that had been thinned and then treated with a prescribed burns lost only 5 percent of their trees, compared to 80-100 percent for thinning alone or 50 percent for those areas not treated at all. But prescribed burns are also expensive to carry out and are not controllable enough to be used near homes.
This may make our public forests sound like a hopeless mess,
condemned to a continued unhealthy and unproductive status. But other
scientific evidence indicates that this is not at all the case. Most
of the dense forests that the Bush Administration and some in the Forest
Service want to thin to return them to “health” are not unhealthy at
all. This is not a pessimistic story. It means that we need to focus our forest fire protection where our homes, communities, and lives are threatened. We do not have to spend tens of billions of dollars trying to save our forests from themselves. The forests do not need it, thank you, and those billion dollar efforts would not work anyway. If we are careful where and how we live in forests and learn to accept fire as a natural part of a healthy forested landscape, both prescribed fire and natural fires, we can both protect ourselves and enjoy the benefits of diverse natural forests. |