Evaluation of the U.S.L.E. for the prediction of soil erosion in forested areas of the Bio-Bio river basin

Abstract

The effects of timber cutting on soil loss, in a Pinus radiata plantation, were studied on soils derived from metamorphic rocks, in a mountain watershed of the Coastal Mountain Range (IX Region, Chile). Local factors in order to calibrate the Universal Soil Loss Equation with the experimental data were determined. Plantation soil loss measurements were carried out in 110m2 plots, equipped with Coshocton samplers, during 1991 and 1992. Treatments were: clearcutting no residues/burned, clearcutting with residues and undisturbed control. The results show a significant increase of soil loss in no residues/burned treatment, with respect to the residues and undisturbed control treatments. No residues/burned to control plots soil loss ratios was 44:1 and 19:1, while between residues and control plots it was 25:1 and 3.4:1, in 1991 and 1992, respectively. Comparison of measured erosion with erosion predicted by the U.S.L.E. model indicated that the equation overestimated annual rainfall erosion by an average of 22% and overestimated monthly erosion by an average of 41%.