Environmental Science: How Forests are Harvested
The world’s forests are one of the most valuable and most endangered resources. Removal of trees, or the destruction of forests, is called deforestation. Throughout much of the developing world, humans clear trees from forests to use them as fuel — firewood — for daily life. In other regions, humans clear forests and replace them with agricultural or grazing land.
Environmental scientists present a few examples of land use management to illustrate the difference between unsustainable resource depletion and sustainable land and resource management.
Clear-cutting is the most common method of timber removal. Clear-cutting removes all the trees in a given area, often by using large machinery. From an economic standpoint, the benefit of this approach is that humans can harvest maximum timber with minimal energy and cost. However, clear-cutting destroys habitats and landscapes in the process. The figure illustrates a patch of clear-cut forest visible as a scar on the forested landscape.
Removing all the trees from a large patch of land leaves the other organisms in the ecosystem without the shelter and resources the trees provided. The open patch increases the amount of sunlight that shines through to the forest floor and the temperature of the habitat surrounding the open patch, both of which affect the organisms that live there. Plus, large bare patches of clear-cut forest leave the soil vulnerable to erosion by wind and water.
Some timber harvesters replant clear-cut patches with a single species of tree. Although this replanting helps control the erosion problem, it doesn’t reestablish the diverse ecosystem that was previously present in the forest habitat.
Selecting certain trees
Because people need to use the resources that forests provide (and because those resources aren’t unlimited), environmental scientists have developed land management practices to help sustain forest resources into the future while using them to meet today’s needs as well.
Selective cutting, also called selective harvesting, is a timber-harvesting approach that’s less destructive than clear-cutting. This method of harvesting removes single trees or a few trees at a time from a forested area, leaving many behind.
Selective cutting of trees requires more time, money, and energy to extract the individual trees, and it can still result in the soil erosion and ecosystem damage that are associated with other forms of timber harvesting (such as road building and air pollution). However, the disturbance to the ecosystem isn’t as dramatic as it is with clear-cutting.
In an effort to find more sustainable ways of using timber resources, scientists and foresters in some places have developed methods of ecologically sustainable forestry, such as using pack animals instead of machinery to remove trees one at a time to reduce the need for roads and the impact on the forest ecosystem.
The goal of this type of timber harvesting is to remove trees without damaging the surrounding habitat or organisms. Although this approach works well on a small scale, it isn’t cost- or time-effective for the commercial-scale logging industry.