Clear-Cutting

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Clear-cutting

Webster's Dictionary defines clear-cutting as "removal of all the trees in a stand of timber." This forest management technique has been used in a variety of forests around the world. For many years, it was considered the most economical and environmentally sound way of harvesting timber. Since the 1960s and 1970s, the practice has been increasingly called into question as more has been learned about the ecological benefits of old growth timber especially in the Pacific Northwest of the United States and the global ecological value of tropical rain forests.

Foresters and loggers point out that there are practical economic and safety reasons for the practice of clear-cutting. For example, in the Pacific Northwest, these reasons revolve around the volume of wood that is present in the old growth forests. This volume can actually be an obstacle at times to harvesting, so that the most inexpensive way to remove the trees is to cut everything.

During the post-World War II housing boom in the 1950s, clear-cutting overtook selective cutting as the preferred method for harvesting in the Pacific Northwest. Since that time, worldwide demand for lumber has continued to rise. Practical arguments that the practice should continue despite its ecological implications are tied directly to the volume and character of the forest itself. Wood in temperate climates decays slowly, resulting in a large number of fallen logs—making even walking difficult, much less dragging cut trees to areas where they can be hauled to mills. Tall trees with narrow branch structures produce a lot of stems in a small area, therefore, the total biomass (or total input of living matter) in these temperate forests is typically four times that of the densest tropical rain forest . Some redwood forest groves in California have been measured with 20 times the biomass of similar sites in the tropics. Those supporting the harvest of these trees and clear-cutting point out that if these trees are not used, it will put increased pressure on other timber producers throughout the world to supply this wood. This could have high environmental costs globally, since it could take 10–30 acres (4–12 ha) of taiga forest in northern Canada, Alaska, or Siberia to produce the wood obtainable from one acre in the state of Washington.

Clear-cutting makes harvesting these trees very lucrative. The number of trees and downed logs makes it difficult to cut only some of the trees, and falling trees can damage the survivors; in addition, they can be damaged when dragged across the ground to be loaded onto trucks. This is made more expensive and time consuming by working around the standing trees. In areas that have been selectively logged, the trees left standing are may be knocked down by winds or may drop branches, presenting a considerable safety risk to loggers working in the area.

Old growth forests leave so much woody debris and half-decayed logs on the ground that it can be difficult to walk through a harvested patch to plant seedlings. This is why an accepted part of the clear-cut practice in the past has been to burn the leftover slash , after which seedlings are planted. Brush that grows on the site is treated with herbicide to allow the seedlings time to grow to the point at which they can compete with other vegetation.

Supporters of clear-cutting contend that it has unique advantages: burning consumes fuel that would otherwise be available to feed forest fires; logging roads built to haul the trees out open the forests to recreational uses and provide firebreaks; clear-cutting leaves no snags or trees to interfere with reseeding the forest, and allows use of helicopters and planes to spray herbicides—the brush that grows up naturally in the sunlight and provides browse for big-game species such as deer and elk.

Detractors point to a number of very negative environmental and economic consequences that need to be considered: particularly where clear cuts have been done near urban areas, plumes of smoke produced by burning slash have polluted cities; animal browse is choked out after a few years by the new seedlings, creating a darkened forest floor that lacks almost any vegetation or wildlife for at least three decades; herbicides applied to control vegetation contribute to the degradation of surface water quality ; mining the forest causes declines in species diversity and loss of habitats (declaration of the northern spotted owl as an endangered species and the efforts to preserve its habitat is an example of the potential loss of diversity); new microclimates appear that promote less desirable species than the trees they replace; so much live and rotting wood is harvested or burned that the soil fertility is reduced, affecting the potential for future tree growth.

Critics also point out that erosion and flooding increases from clear-cut areas have significant economic impact downstream in the watersheds. Studies have shown that since the clear-cut practice increased following World War II, landslides have increased to six times the previous rate. This has resulted in increased sediment delivery to rivers and streams where it has a detrimental impact on the stream fishery.

Loss of critical habitat for endangered species such as the spotted owl and the impact of sediment on the salmon fishery have resulted in government efforts to set aside old growth forest wilderness to preserve the unique forest ecosystem . The practice of clear-cutting with its pluses and minuses, however, continues not only in the Pacific Northwest, but in other forests in the United States and in other areas of the world.

Clear-cutting and rain forests

Another area where clear-cutting has become the focus of ecological debate is in the tropical rain forests. Many of the same economic pressures that make clear-cutting a lucrative practice in the United States make it equally attractive in the rain forest , but there are significant environmental consequences.

Since 1960, the world demand for wood has increased by 90%, and as indicated above, the pressure to supply lumber to meet this demand has also increased. Nearly one-half of the Earth's rain forests have been cut in the last 30 years. Besides the demand for building material or fuel, these forests are also subject to significant clearing to later be worked to produce food in new agricultural areas and to facilitate the exploration for oil and minerals. If this loss continues at present estimated rates, the rain forests will be totally harvested by the year 2040.

Rain forest activists continually work to remind the world of the importance of the forests. Locally, for instance, the presence or absence of the rain forest can change the climate and the local water budget. For example, times of drought are more severe and when the rains come, flooding is increased. As well, rain forests can have a major impact on the global climate. When they are cut and the slash burned, significant amounts of carbon dioxide are released into the atmosphere , which may contribute to the overall greenhouse effect and general warming of the earth.

The biological diversity of these forest ecosystems is vast. Rain forests contain about one-half the known plant and animal species in the world and very few of these species have ever been studied by scientists for their potential benefits. (More that 7,000 medicines have already been derived from tropical plants. It is uncertain how many more such uses are yet to be found.)

Most rain forests occur in less-developed countries where it is difficult to meet the expanding needs of rapidly increasing populations for food and shelter. They need the economic benefits that can be derived from the rain forest for their very survival. Any attempt at stopping the clear-cutting practice must provide for their needs to be successful. Until a better practice is developed, clear-cutting will remain an environmental issue on a global scale for the next several decades.

[James L. Anderson ]