Use of a ground‐based scanning lidar for estimation of biophysical properties of western larch (Larix occidentalis)

Abstract

Ground‐based laser scanners represent a relatively new technology that promises to enhance the ability to remotely sense biophysical properties of vegetation. In this study, we utilized a commercially available discrete‐return ground‐based laser scanning system to sample properties of western larch (Larix occidentalis) in a northern Idaho forest. Three young trees <5 m in height were scanned before and after leaf abscission in the autumn of 2004. Leaf areas represented by the number of laser returns were estimated by subtracting leaf‐off laser returns from leaf‐on returns. Leaf areas represented by number of laser returns were significantly correlated with manual‐based estimates of leaf area (r ² = 0.822). Ratios of woody‐to‐total tree area were estimated based on number of laser returns from woody material. Ratios of woody‐to‐total area ranged from 0.24 to 0.58 for nine one‐metre sections of tree for which estimates were made. Ratios of woody‐to‐total area were also estimated using intensity of laser returns and fell near the range of estimates made using the number of laser returns. Improved estimation of leaf area, woody‐to‐total area ratios, and other biophysical parameters using ground‐based laser scanning technology may be possible with a careful consideration of instrument specifications and sampling design.

Acknowledgements

The HDS 3000^TM laser scanner was generously provided by Jay Roman and colleagues at Oglala Lakota College. The authors thank Dean Scott of D.C. Scott CO Land Surveyors for technical information, advice, and training in the use of the laser scanner. We also thank Sookie Bang, Kerri Vierling, Patrick Zimmerman, and two anonymous reviewers for providing useful comments on earlier drafts of the manuscript, and acknowledge special help from Kerri Vierling in site reconnaissance and leaf collection. We are grateful to Ross Appelgren and others at the University of Idaho for access to the Experimental Forest, and to Jeff Evans, Mike Falkowski, Andrew Hudak, and Alistair Smith for assistance in collection of laser scans. This work was partly supported by NASA EPSCoR grant NCC5‐588.