STATISTICAL RELIABILITY IN SMS'S PRE-FELLING INVENTORY: INFERENCES AND IMPLICATIONS FOR SAMPLING TREE DENSITY, BASAL AREA AND VOLUME
Keywords:Sampling intensities, species group, Selective Management System, pre-felling inventory, confidence (probability) level, error level, dipterocarp, non-dipterocarp, Malaysia
This study was carried out on a randomly chosen 30-ha (500 x 600 m) forest area within the 50-ha Demography Project of the Forest Research Institute Malaysia (FRIM) in Pasoh Forest Reserve, Negeri Sembilan. A 30-ha study area was used as data set. A higher sampling intensity was needed when sampling tree size
classes andspecies groups thatwerelowerintheirfrequency of occurrence. Dipterocarp species group (ALL DIPT) needed a higher sampling intensity to detect its occurrence compared to non-dipterocarp species groups (ALL NON-DIPT). A different intensity of sampling was required when considering either diameter classes, species groups, plot sizes or tree parameters separately, and also when different confidence and error levels were used. The implications of attaching confidence and error levels to the intensity of inventory by species group currently used in Selective Management System are also discussed.