by Dominick Murray

Created on: November 08, 2007

The thinning of forests is a natural process as much as it is an anthropogenic one. It has been carried out since the emergence of trees and forests as organisms and communities by the effects of wind. Wind plays an important and natural role in regulating the size and structure of many stands of trees. Human beings, either as individuals or on behalf of forestry agencies also play a role in the thinning of forest stands. There are several reasons for the practice of thinning forests by humans. These reasons, and the subsequent benefits of the practice are mirrored by the impact of natural, wind-blown trees.

1)Thinning increases the growth rate of trees.

In commercial forest plantations the juvenile trees, lets say for example Sitka Spruce, are planted very densely, perhaps as close as one meter apart. As they grow they compete with each other for nutrients from the soil and sunlight. As the stand increases in age and subsequent size, due to the competing nature of trees they will ultimately begin to grow with thinner girth but taller in height, henceforth competing to get the sunlight. This competition will leave commercial forestry operation with trees which do not have adequate girth to fulfill the needs of their markets, for example producing timber for building. This is obviously not in the best interests of forestry operators so thinning is seen as the best possible solution to getting rid of this problem.

Once the trees have been thinned this opens up the stand, allowing more space between individual trees and reducing competition. This will allow the trees to grow with increased girth and thereby increase their value and the health of the stand.

2)Thinning can lead to increased levels of nutrients in the forest.

The thinning of trees can lead to an increase in the available nutrients in the forest. If the brash (branches, stems, needles etc) is left on the forest floor, as is common practice in the U.K. this can allow the nutrients contained within to leach back into the soil, and therefore increase the fertility of the stand. The root system may also be left in the ground after the trunk of the tree has been harvested. This will also return large amounts of nutrients into the ground. In the case of whole tree harvesting, the tree, stems and root system are all removed, however, in order to prevent the whole sale removal of nutrients from the forest, the tree will be left in-situ in the forest in order to dry out, and therefore shed it's branches and needles,

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