Storm runoff and sediment losses from forest clearcutting and stand reestablishment with best management practices in East Texas, USA
Nine small (2.5 ha) and four large (70-135 ha) watersheds were instrumented in 1999 to evaluate the effects of intensive silvicultural practices with best management practices (BMPs) on runoff and stream water quality in the Western Gulf Coastal Plain of East Texas, USA. Two treatments were implemented in 2002: a conventional treatment with clearcutting and herbicide site preparation, and an intensive treatment that added subsoiling, fertilization, and a release herbicide application. Watershed effects were compared with results from a previously conducted study on the same watersheds in 1981, in which two combinations of harvesting and mechanical site preparation without BMPs were evaluated. Due to the reduction in evapotranspirational demand, total storm runoff increased on all six treated small watersheds following harvest by 0.94 to 13.73 cm in 2003. Runoff increases were not statistically significant on the treated large watersheds. Total first-year sediment loss was significantly greater on two of the conventional and one of the intensive small watersheds. The greatest first-year increase was 540.1 kg/ha, only one-fifth of that observed on these watersheds from shearing and windrowing without BMPs in 1981. First-year sediment loss was significantly greater on the intensive large watershed following harvest, but not on the conventional large watershed. These data suggest that BMPs are very effective in reducing potential water quality impacts from intensive silvicultural practices.