摘要
农防林的结构特征与作物产量关系密切。南北走向的农防林增产效益高于东西走向的农防林,作物的增产效益、防护面积随单位农防林地面积冠幅、冠体、密度、林木平均高度的增加呈单峰曲线变化,农防林占地比率呈凹曲线变化。作物增产率最高、农防林占地比率最小、防护面积最大时,相应的最适农防林单位面积林地冠幅为2～4m^2/m^2,冠体4～6m^2/m^2,林木密度0.1～0.2株/m^2,林木高度8～20m。
Through the field investigation,relationships between shelterbelt structure and crop yield were discussed.The result shows that the shelterbelts with SN direction have a higher benefit than those with EW direction.With increasing crown size per unit area,crown volume,denisity and average tree height,benefit of increasing crop yield and protective area vary as a single peak curve,and area ratio of shelterbelt to crop varies in a hollow curve. The optimum structure of shelterbelts with highest yield increasing rate,min- imum area occupied by shelterbelts and maximum protection region is crown size 2～4m^2/m^2,crown volume 4～6m^3/m^2 and stand density as 0.1～0.2 trees/m^2,tree height 8～10m.
出处
《陕西林业科技》
北大核心
1991年第2期49-52,共4页
Shaanxi Forest Science and Technology
