Lidar-derived Site Index in the U.s. Pacific Northwest – Challenges and Opportunities

Site Index (SI), a key inventory parameter, is traditionally estimated by using costly and laborious field assessments of tree height and age. The increasing availability of reliable information on stand initiation timing and extent of planted, even-aged stands maintained in digital databases suggests that information on the height of dominant trees suffices for assessing SI. Light Detection and Ranging (LiDAR) is a technology proven capable of providing reliable estimates of tree height even at the individual-tree level. A rigorous evaluation of LiDAR-enabled SI estimation performed on coniferous stands of the coastal U.S. Pacific Northwest indicates that where stand structure and topographic conditions support a high-fidelity assessment of ground elevation, accurate (R_=_0.88) estimates of SI should be anticipated. In more challenging conditions the accuracy of the estimates lessens substantially. A limited evaluation of spatial SI predictions indicates that the distribution of the index might not always conform to the expectations commonly held by forest managers and planners.