The Effect of Clearcut Deforestation on Physical and Chemical

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The Effect of Clearcut Deforestation on Physical and Chemical


Properties of Soils

Clearcut deforestation is done for a variety of different purposes. Frequently, sites owned by lumber companies are clearcut, replanted, fertilized, and maintained to keep a cyclic supply of lumber of uniform species, size, and age. Some lumber companies claim that in their tree harvesting practices can raise mature lumber in forty years (Wood, 1971), while most tree harvesting is on 70-100 year cycles. Deforested land can alternately be used as grazing or farming land. Both of these purposes involve a variety of different techniques depending on the company, location, and the geomorphology. In all of these cases, the clearcut site goes through a
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Other cases such as agricultural use or livestock grazing may use a combination of windrowing and burning, possibly also including chemical herbicides (Farrish, et al., 1993).

By removing vegetation from a site, there is decreased organic transpiration of water, thereby increasing the storm runoff and erosion. Vegetation serves to slow overland runoff, and without the trees and grasses, the overland runoff can flow fast enough to erode the soil. Removal of vegetation also exposes the soil to splash erosion, which causes erosion-resistant soil aggregates to break apart and makes the soil more vulnerable to erosion and transport (Beasley and Granillo, 1985).

The practice of drum-chopping or shearing followed by windrowing affects the physical properties of the soil substantially. Windrow machinery stirs and loosens the upper soil layers and creates channels for overland runoff flow. To avoid the runoff erosion while still using the technique of windrowing, logging companies occasionally make their windrows parallel to the contours of the slope. This practice only slightly decreases the erosion directly due to windrowing. Hauling roads also create ruts that become channels for runoff, especially in the regions where the roads cross streams.

Compaction of the soil is another detrimental effect related to clearcutting. In most cases, vehicles and machinery that are used in the logging and site…

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