Forest measurement and monitoring using high-resolution airborne lidar

Abstract

Airborne laser scanning has emerged as a highly-accurate, high-resolution forest survey tool, providing the opportunity to develop and implement forest inventory and monitoring programs using a level of detail not previously possible. In this paper, we will present results from several research studies carried out at a study area within Capitol State Forest in the state of Washington, where we investigated the utility of LIDAR for measurement of terrain and forest structure characteristics. Previous studies at this site have shown that LIDAR can be used to accurately measure terrain elevation even under dense forest canopy. The results of another study have indicated that LIDAR can also be used to accurately estimate a number of forest inventory variables, including basal area, stem volume, dominant height, and biomass. The laser-reflection intensity information provided by LIDAR can also be used for species classification. Individual tree crowns can be recognized by using computer vision algorithms applied to a detailed LIDAR-based canopy surface model. This approach can be used to extract measurements of individual trees, including top height and crown base height. Preliminary results have shown that if high-density LIDAR data are collected in different years, measurements of individual-tree height growth can be obtained for an entire forest area, allowing for detailed, spatially explicit analyses of site quality and productivity.