【摘要】 通过对陕西、甘肃和宁夏有天牛危害的杨树林的２０７块标准地资料的分析研究，得出杨树天牛虫害的平均株虫口密度与有虫株率之间的关系可用指数函数曲线ｙ＝ａｅｂｘ（ｂ＞０）来描述。更多还原

【Abstract】 Based on the data of 207 poplar plots damaged by poplar longicorn from Shaanxi,Gansu and Ningxia the relationship between average population density of poplar longicorn and the ratio of damaged trees could be discribed as y=aebx(b>0). Where y is the average population density of poplar longicorn, x is the ratio of damaged trees, a and b are constants.更多还原