农田防护林带能够保护农田,增加粮食产量。但是,由于树冠遮荫,影响农作物的光合作用,加之树木根系与作物争水、争肥,往往使林缘附近农田出现明显的减产带,即所谓林带胁地。胁地范围一般在林缘附近1～1.5倍树高以内,并且有“胁北不胁南,胁东不胁西”的规律。采取合理的措施,可以减轻胁地程度,提高林缘作物产量。 Farmland shelterbelts protect farmland and increase food production. However, the shade of the canopy affects the photosynthesis of crops and the contention of trees and crops for water and fertilization often leads to obvious yield reduction zones in the farmland near the edge of the forest. The range of threatening land is generally within 1 ~ 1.5 times the height of the tree near the edge of the forest, and there is a rule of “threatening the north not threatening the south and threatening the east without threatening the west”. Take reasonable measures to reduce the extent of the threat of land and increase the yield of forest edge crops.