Windthrow risk diagnosis for park trees based on the drag coefficients of tree crowns and the measurement of tree form

探讨了园林树木风灾风险的定量评估方法，提出了一种风灾诊断程序。提出了一种利用实测风速和树干偏折数据估算树木阻力系数的野外试验方法。利用所得到的阻力系数，可以计算出作用在树干和根土板上的力矩与风速的关系。为了评估风摔阻力与茎断裂，一个非破坏性的方法来确定树干横截面的形状。此外，还进行了公园树木的拉拔试验

Methods of quantitative evaluation for windthrow risk of park trees were discussed in order to propose a procedure for windthrow diagnosis. A field test method was developed to evaluate drag coefficients of trees, using measured data of wind speed and stem deflection. The moment acting on stem and root-soil plate can be calculated as a function of wind speed, using the obtained drag coefficients. To evaluate windthrow resistance with respect to stem breakage, a nondestructive method for determining the shape of a trunk cross section was developed. Furthermore, pull-down tests of park trees were conducted