Wind damage risk estimation for strip cutting under current and future wind conditions based on moment observations in a coastal forest in Japan

Abstract

In Japan, coastal forests have been constructed along the seashore to prevent houses and fields from disasters caused by strong winds. A management method needs to be established to regulate the stand density. There is also the possibility that wind speed will increase in the future because of the increasing strength of tropical cyclones caused by climate change. We evaluated the current and future risk of wind damage associated with strip cutting of Japanese black pine forest based on moment work on sample trees. We established a research site consisting of three groups of trees: group A faced a 1.2-m cutting strip, group B faced a 5-m cutting strip, and group C was the control. Group B was vulnerable to strong winds because the normalized critical wind speed (CWSnml) was significantly smaller than that in the other groups. The damage risk was evaluated by comparing CWSnml with the criterion, a 50-year return period of wind speed. In the current conditions, 5-m cutting had a certain degree of risk, and 1.2-m cutting showed a low risk. Under the future wind conditions, 5-m cutting was found to show high risk so that most of the trees did not meet the criterion. The 1.2-m cutting showed a low risk even in the future conditions. Our results clearly reveal the significant changes in the stability of remaining trees against strong winds after strip cutting. This study suggests a method to quantify the risk involved in forest management.