UTILIZATION OF DISCRETE-RETURN AIRBORNE LIDAR FOR IDENTIFICATION OF SMALL CANALS IN THE CLOSED-CANOPY OF PEAT SWAMP FOREST IN CENTRAL KALIMANTAN INDONESIA

摘要

Peat swamp forests of South East Asia have contributed the largest portion of global greenhouse gas emissions, due to causes associated with forest resource extraction, including logging, land conversion to agriculture and fires. Accurate mapping of actual and historical infrastructure in peat swamp forests, in particular illegal roads and canals, is crucial for peat land management planning on hydrological restoration and forest protection activities. However, identifying these features using optical satellite imageries is still problematic, even using high resolution satellite imagery or aerial photos. They are often very narrow and covered by closed-canopy forests. Our study aims at identifying small canals and logging roads in peat swamp forest in Central Kalimantan using discrete airborne lidar data. These logging trails and small canals are associated with historical or illegal timber extraction. We used a lidar-derived spatial data layer (relative density model (RDM)) characterizing patterns in the 3-D forest canopy volume, and a normalized digital terrain model (DTM) generated from 2.8 pulse m"2 density lidar data for assessing existing logging trails and small canals. We visually digitized the logging roads and small canals from the models and compared the results with field measurement using GPS.