The Estimation of Wind Risk in Forests Stands using Airborne Laser Scanning (ALS)

Wind is the most important abiotic hazard for forestry in Britain. Most forests have been established in upland areas in locations that are commonly affected by high winds and poor soil conditions. Strong winds cause significant loss of timber every year in Great Britain and have profound effects in wood quality though increases in the proportion of compressed wood, poor stem straightness, repeated loss of leaders and important alterations in the relationship between height and diameter. ForestGALES (Geographical Analysis of the Losses and Effects of Storms in Forestry) is a process-based model that provides a better understanding of the variability in the wind forest climatology, an estimation of the critical wind speed to cause wind damage and the return period for that damage to occur. At present, ForestGALES is currently being linked to ArcGIS and LiDAR data has been evaluated to estimate the effects of stand structure in the probability of wind damage. To do so, the model has been adapted to operate with tree lists generated by LiDAR. In this context, three canopy delineation algorithms have been tested in connection to existing allometric relationships. TreeVAW (POPESCU, 2006), TreesVIS (WEINACKER et al., 2004) and ITC (GOUGEON, 2005). The results provided a valid method for evaluating the effects of stand variability on wind damage and the effectiveness of Airborne Laser Scanning for monitoring forest structure and its effects on wind stability.