影响农田防护林防风效益的主导因子探讨

The Study on the Dominant Factors of Wind Reduction Effect of Farmland Shelterbelt

通过对半干旱风沙区单林带、林网、林农间作、片林等不同类型农田防护林结构和防风效益的调查研究，提出了疏速度、林带间距、树高与林带宽度的比值、单位面积树冠体积分别是影响各类防护林防风效益的主导因子。确定了单林带最佳结构时的疏透度为０．３，有效防风距离为树高的１３．８倍。

Investigation and study are made on the structure and wind reduction of different farmland shelterbelts, which are forestbelt, intercropping of trees and crops,part forest an so on. The conclusion are that the dominant factors of wind reduction effect are degree of density,distance of forest belt,the ratio of the tree height and width of forest belt,tree crown volume of area,that the degree of density is 0. 3 when the single forestbelt is the best structure, that the effective wind reduction distance is 13. 8 times as much as the tree height.