RESIDUAL STAND DAMAGES CAUSED BY CONVENTIONAL AND REDUCED IMPACT TIMBER HARVESTING IN THE NATURAL FOREST

The objective of this research is to know the effect of reduced impact timber harvesting on residual stand damages in natural tropical forest. The effect of conventional and reduced impact timber harvesting (RITH) on residual stand were studied using the data of three plots with each size of 100 m x 100 m placed in timber collection site, middle skiddtrail and tips of skiddtrail, respectively. Field research was conducted in the concession area of PT. Inhutani II, East Kalimantan. Research plots consisted of timber harvesting plots using conventional technique and timber harvesting plots using RITH technique. The results of the research show that that the potency of commercial timber species in conventional timber harvesting and RITH are as follows: 408 N/ha and 432 N/ha. The degree of residual stand damages based on tree population and stage of vegetation development in conventional timber harvesting and RITH was as follows : for seedlings 34.42 % and 23.17 %, for saplings 35.13 % and 21.72 %, for poles and trees 33.15 % and 19.53 %. Based on the size injury of every individual tree, the degree of the trees damages caused by timber harvesting in conventional timber harvesting and RITH was as follows : trees heavy injury 64.66 % and 57.20 %, trees medium injury 20.30 % and 24.00 % and trees light injury 15.03 % and 18.80 %. The most type stand damage are the falling down 36.84 % and 32.01 % and broken stem 22.78 % and 21.25 %. The research indicates that conventional timber harvesting in the tropical natural forest causes heavier damage on residual stand when compared to reduced impact timber harvesting.