Abstract

Reliable information on the effectiveness of control measures in reducing soil erosion and sediment delivery to streams associated with forest clearcutting operations is needed to support the development of best management practices for soil and water conservation in forest areas. To address this need, the efficiency of woody trash barriers installed along the contours in reducing soil loss and sediment delivery to streams was undertaken in an area exposed to highly erosive rainfall events immediately after final forest harvest. The site selected for the study is located in south central Chile, is characterized by a mean annual rainfall of about 2300 mm and wet winters. Soil redistribution associated with a 663 mm event was measured within 15 m and 30 m long plots located between trash barriers on a 22% slope using both the ⁷Be technique and erosion pins. Both approaches provide similar estimates of the spatially integrated soil redistribution for each of the studied plots. The results show that the construction of appropriate linear trash barriers can be effective in reducing sediment delivery to watercourses, and indicate that a barrier spacing of 15 m should be more effective than a spacing of 30 m in reducing net erosion.

Keywords: Soil loss; sediment flux; drainage system; forest clearcutting; ⁷Be; erosion pin