ESTIMATION OF THE HARVESTABLE POTENTIAL AFTER LOGGING IN A LOWLAND MIXED DIPTEROCARP FOREST OF EAST KALIMANTAN

Abstract

A model is used to assess in a simple way the number of dipterocarp stems above the cutting limit of 60 cm dbh through time after logging and silvicultural treatment. Different scenarios of simulation are set up depending on whether reduced impact logging techniques (RIL) and/or silvicultural treatment is applied. The data used are those of the STREK project implemented in East Kalimantan, Indonesia, complete with data from the literature. A scenario of reference is built with the assumptions of the TPTI (Indonesian selective cutting and planting system). In the strict observance of the TPTI, with RIL methods and regular subsequent thinnings, the time required to recover the initial number of dipterocarp stems above 60 cm dbh is around 50 y. With more realistic scenarios, this time is around 100 y or more. The use of RIL methods with silvicultural treatment leads to a reduction of 15 y compared with the recovery time of the conventional logging. After 35 y, the official TPTI cutting cycle, the simulation foresees a potential harvest of about 5 stems ha^-1 with RIL methods and one thinning compared with 8 trees logged at the first harvest. The method does not take into account the volume and does not distinguish the injured or misshapened trees but provides a basic, adaptable tool to be used by field managers.