ESTIMATING DBH OF COMMERCIAL TREES FROM STUMP MEASUREMENTS IN MALINAU, EAST KALIMANTAN

摘要

Changes in the system of forest harvest have potentially important implications for the future extent and quality of natural forest resources. Throughout the Malinau district in East Kalimantan there is intensive harvesting of timber from natural forest. It is important for planners and managers in such regions to be able to estimate quantities and proportions of wood volume or tree biomass extraction from particular forest stands over a certain time period. One way of calculating harvest removals isto estimate volume/biomass from cut stumps. To estimate biomass extractions, if quantitative relationships between stump measurements and reference diameter of trees have not been established previously, measurements made on stumps will be limited to the use of analytical techniques that involve counts and frequencies. Pre-existing variables such as basal area, volume or aboveground biomass cannot be estimated from stump measurements in such cases. Tree diameters at some reference stem height are necessary for computing important tree variables such as basal area, volume and aboveground biomass (Chhetri & Fowler 1996). Diameter at breast height (dbh) is the most commonly used reference diameter and it is measured at 1.37 m above the ground in the USAand Canada, and 1.30 m in countries using metric system (Kohl 1993).