通过对三江平原垦区农田防护林网内作物产量的测算与分析认为，造林后前５的年因林带占地、胁地给作物造成的减产大于增产；６年时产量达平衡，此时树高达７．６ｍ；７年后增产大于减产；１０年时林带给作物带来的总增产量与总损失量持平，此时树高平均为１１．４ｍ；１１年以后，林带将给农业生产带来纯的净增产效益。 According to the calculation and analysis of crop production in farmland shelterbelt in the reclamation area of ​​Sanjiang Plain, the first 5 years after afforestation is due to the land occupied by forest belts, and the yield reduction caused by threatening crops is greater than the increase; the output reaches its equilibrium level in 6 years .6m; 7 years after the yield increase is greater than the cut; 10 years when the total output of forest yield brought to the total loss and the amount of flat, then the average height of 11.4m; eleven years later, the belt will bring pure agricultural production Net increase production efficiency.