Risk assessment of wind disturbance in Japanese mountain forests

Wind damage of coniferous plantation forests containing hinoki (Chamaecyparis obtusa) and natural broad-leaved forests was studied in the Japanese mountains. Wind conditions determined using an air flow simulation model and historical wind disturbance records were integrated within a Geographic Information System (GIS). Based on the data set, the relationships between wind disturbance, wind speed, and stand height in plantation and natural forests were analyzed. A logistic analysis technique was applied to assess the probability of wind disturbance in stands that remained intact or were damaged as a result of the Isewan Typhoon. The results indicate that higher wind speeds and greater stand heights increase the probability of wind disturbance in both plantation and natural forests. Cross tabulation of the observed disturbance percentages in relation to wind speed and stand height in coniferous plantation forests and natural broad-leaved forests revealed that the former are more likely to be disturbed by strong winds than the latter. The logistic regression model enabled us to predict the likelihood of wind disturbance at our study site. Our results confirmed that it is possible, using wind condition prediction software, to analyze wind disturbance in mountain forests with complex terrain and steep slopes.