杨粮间作系统中林木遮荫作用研究

THE STUDY ON SHADING EFFECT UNDER POPLAR CROP INTERCROPPING SYSTEM

本文报道了利用遮荫指数和遮荫程度 ,描述华北平原农区杨粮间作系统毛白杨对农田的遮荫情况。结果说明 ,毛白杨幼林 (株行距 3m× 2m× 18m) 1～ 7a生的遮荫指数为 1 3%～ 6 7 8% ,遮荫程度是 0 3%～16 5 % ;中龄林—成林 (株行距 4m× 30m) 10～ 14a生的遮荫指数是 5 1 3%～ 76 0 % ,遮荫程度为 2 2 8%～2 8 1%。利用遮荫程度表示林木对农田的遮荫情况比用遮荫指数更符合实际 ,并且提出 15

The poplar(\%Populus tomentosa\% Carr.) shading on farm field, with shading index and shading degree, was reported under poplar crop intercropping system in Northern China farm region. The results demonstrate that poplar young growth (spacing 3?m×2?m×18?m) brought on shading index 1 3%～67 8% and shading degree 0 3%～16 5% on farm field when stand ages were 1～7 years, and near and mature stand (spacing 4?m×30?m) resulted in shading index 51 3%～76 0% and shading degree 22 8%～28 1% when stand 10～14 years as well. But using shading degree to express shading on farm field is better than shading index, and shading degree 15% is suggested the maximum shading degree that could be accepted in farm field.