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东北西部、内蒙东部营造的杨、柳、榆等阔叶林带,相当一部分已接近成熟阶段,生长衰退,防护效果大为减弱;同时,在农田播种时期仍处于无叶状态,对春耕播种、施肥都带来了困难,起不到应有的防护效果。因此,采用常绿的针叶树种——樟子松和油松,以滚带方式更替阔叶林带,逐步改变防护林的结构和组成,对提高农牧区的生产水平有很大的现实意义。据我所1962年在辽宁省昌图县付家地区
In the western part of Northeast China and eastern Inner Mongolia, broad-leaved forest belts such as poplar, willow, elm and other broad-leaved forest belts are in the mature stage, with the recession and the weakening of the protective effect. At the same time, All have brought difficulties, can not achieve the desired protective effect. Therefore, the use of evergreen conifers, Pinus sylvestris var.Mongolica and Pinus tabulaeformis, to replace broad-leaved forest belts by roll-to-roll and gradually change the structure and composition of shelterbelts are of great practical significance for improving the production level in farming and pastoral areas. According to my company in 1962 in Changtu County, Liaoning Province to pay the home