Erosion Control in the Tropical Rainforest Catchments using Modified Intensive Rehabilitation

Tropical rainforests in Indonesia is currently managed by Intensive Forest Management System (IFMS), characterized by selective timber harvesting and intensive rehabilitation to enrich standing stock. This study conducted quantitative evaluations on catchment scale impacts of IFMS during each selective logging (SL) and intensive rehabilitation (IR) stage. SS concentrations were measured in three headwater catchments located in tropical rainforests of the Bukit Baka Experimental Catchments, Central Kalimantan, Indonesia. While no forestry operation was conducted in catchment A, operations based on IFMS were conducted in catchments B and C. A combination among the great surface disturbance by skid trails, large tree extraction ratio, and high slope angle of catchment B resulted in the greatest SS. During the post-IR period, SS concentration of catchment B did not show decreases in comparison with that during the post-SL period. In catchment C, increases in SS concentration were observed during the post-IR period. Thus, this study indicated that IR of IFMS was not effective to decrease SS concentration in the initial stage of the post operation period, but the modified intensive rehabilitation with considering the contour and topography potential ly significant to control erosion.