Assessing success of forest selective management system using geospatial technology

Abstract

Since 1960s, forestry activities in Malaysia have been pushed towards steeper and erosive hilly areas which comprised of less big trees and less seedlings requiring a more precautious management practice in achieving forest sustainability. Hence in 1978, the Selective Management System (SMS) concept was adopted, planned for 25 years harvest cycle ensuring the next harvest with per hectare minimal 32 trees of above 30-45 cm diameter, producing minimal output of 40-50m3/ha, enriched with more Dipterocarp species. SMS conducted activities of pre and post felling inventories, flexible tree cutting limits and post felling treatment. However, after more than 30 years the success of SMS has not been fully determined though many visual observations inferred reduced merchantable stand and higher damaged of the residual forest. Consequently, this project intent to assess the success of SMS using geospatial technology. In this project, five forest parameters as SMS success indicators were measured; (a) forest density - estimated from Sentinel satellite image (10 x 10m) and GLAMA-GAP apps (b) tree number - enumerated at site plots (c) tree volume - determined by site plots measurement (d) tree composition - determined at site plots and (e) harvesting cycle duration - determined by historical data observation. Based on site measurement, it was found that all the plots have more than 32 trees/ha of above 30-45 cm diameter, comprising tree volume more than 40m3/ha and Dipterocarp species were 75% more than non-Dipterocarp. Meanwhile, NDVI from Sentinel 2 satellite image revealed that the density of the logged forest were more than 80% and subsequently confirmed 100% accurate by GLAMA-GAP apps. Results acquired concluded that in these project areas, SMS proved to be successful by complying all the requirement of SMS residual forest characteristic.