Author : Djoko Marsono

Summary : The effects of Indonesian selective cutting (TPI) on the structure and regeneration of lowland tropical dipterocarp forest in East Kalimantan, Indonesia were studied. The study was conducted in Georgia Pacific Concession areas in East Kalimantan and Department of Soil, Faculty of Agriculture Gadjah Mada University, Yogyakarta, Indonesia, from November 1979 to May 1980. The study areas were classified, as virgin forest, newly logged over area, two-year logged over area, four year logged over area, six-year logged over area and eight year logged over area. Data on logging damages on living trees and some environmental factors such as relative humidity, air and soil temperature, light transmission ratio and soil macro-nutrients were also monitored. Results show that the lowland natural dipterocarp forest may not fulfill the requirements of regulations unless the valuable trees with 20 cm diameter and above would be included as main trees for future harvests. Dipterocarp species were found to b contiguously distributed while most of the non-dipterocarp species were randomly distributed. The distribution of both species was almost constant before and after logging. The non-dipterocarp species mignt not have been affected by the mosaic environmental factors and grew well immediately after logging. However, in some dipterocarp speicies, growth was stimulated by an open canopy, and becoming dominant afterward. Vertical arrangements of residual stand were observed to change from the original condition in terms of the continuity if each canopy layer arranged either vertically or horizontally. The regeneration succession pattern after logging followed the opening and closing of the canopy. All environmental factors were found to affect regeneration succession, and perform a complex environmental gradient on the ordination diagram. However, among those factors, light transmission ratio, air temperature and relative humidity showed the highest effect. Logging damages on living trees were observed. Fallen and broken off trees showed the highest damage value of 45 percent.