Estimation of forest stand structures using airborne LiDAR

Abstract

This paper is a review with regard to the past studies estimating forest stand structures using airborne light detection and ranging (LiDAR). The LiDAR, which has developed greatly since the 1990s, is an active remote sensing technology that directly obtains data inside the canopy, such as ground elevation, by penetrating the tree canopy; that is, it can acquire vertical, in addition to horizontal, information about the forest, unlike passive optical remote sensing technologies. LiDAR-based forest measurements have been developed mainly in Europe and North America, and have been conducted mainly over large-scale coniferous forests consisting of relatively few tree species, compared with broad-leaved forests consisting of many tree species. The first interest in the application of LiDAR to forest measurement was to determine terrain elevations. Among the forest structural variables, tree height has been most intensively focused on by LiDAR-based estimation. Other forest variables, such as crown diameter, biomass, timber volume, fractional cover, leaf area index, tree species, and three-dimensional foliage distribution, have been also estimated using LiDAR data. The recent interests in the LiDAR application to forest survey include generalization of estimation methods of forest structure, synergetic use with other types of data such as optical image, and wildlife habitat characterization. For the future, one solution of cost reduction of LiDAR data acquisition seems effective data use including collaborative partnership for data sharing and publication. It is important to establish methods estimating heterogeneous forest structure with high accuracy for operational use of LiDAR data.