California, USA — Increasing numbers of people in our community are becoming alarmed by the fact that forests in Shasta County and throughout the forested areas of California are being clear-cut by large timber companies such as Sierra Pacific Industries and Roseburg Lumber.
Clear-cutting consists of cutting virtually all the trees in 20 or 30-acre areas. After the trees are harvested, the area is replanted with densely spaced small trees of the same age consisting of one or two species. A diverse forest of many species and many ages of trees and shrubs has been replaced by a tree plantation.
Many problems result from this process. They include the loss of habitat for wild animals, the use of herbicides to kill competing plants which then pollute our waterways, increased fire danger from tree plantations, and the loss of the beauty and recreational opportunities that forests provide. But the most irreversible and catastrophic aspect of clear-cutting is its contribution to global warming.
Carbon dioxide is one of the major greenhouse gases; when it is released into the atmosphere in larger quantities than can be absorbed, it causes global warming. Trees store carbon dioxide in their branches, trunks and roots, keeping it out of the atmosphere. The timber industry claims that clear-cutting followed by planting tree farms actually stores carbon dioxide rather than releasing it, thus helping to prevent global warming. The grain of truth in this argument is that young trees absorb carbon from the atmosphere and store it more quickly than older trees. But this is like looking at one frame of a movie to try to understand the entire film.
To understand the meaning of the entire film, however, we need to look at another frame: what happens when tree plantations are planted. After clear-cutting, the soil is prepared for replanting by the use of heavy machinery that rips open the soil, allowing organic matter in the soil to rot. That rotting process releases more carbon into the atmosphere than plantation trees will absorb during their first 10 years of growth, according to research cited by the U.S. Department of Energy. Given the urgency of combating global warming, it makes no sense to wait 10 years for harvested forests to reach the point where the amount of carbon absorbed equals the amount that was released by clear-cutting.
Tree plantations contribute to global warming in another way: They are highly vulnerable to forest fires, and fires release more carbon into the atmosphere. According to the California Board of Forestry, younger forests are more susceptible to fires “due to the lower height and size of small trees.” Without large trees with thick bark that can resist fire and provide a cooling canopy for the forest, forest fire danger increases.
Furthermore, clear-cutting and global warming interact to exacerbate the effects of one another. Erosion caused by clear-cutting results in increased runoff of rain earlier in the spring. At the same time, as the temperature has risen over the last several decades due to global warming, the snowpack is decreasing; this year, snowpack in the Sierra Nevada was less than a third of average. In recent years, snow is melting earlier in the spring. As a result, the mountains of California are not effectively playing their historic role of storing water from snow and rain until summer when the water is needed in the valleys.
These changes result in forests that dry out earlier in the year, resulting in a significant increase in the number, intensity and length of forest fires. Those fires then release more carbon into the atmosphere, increasing global warming, which in turn creates more fire danger. This feedback loop is difficult to stop.
As a society, we need to tackle global warming through many strategies. One important strategy is managing forests to store as much carbon as possible, which means ending clear-cutting and returning to selective logging, which was the typical harvesting method for timber until the mid-1990s. We must ask the large private timber companies to change their practices before it is too late, and demand that our state government make the practice of clear-cutting large acreages illegal.