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关于农田防护林的林带走向问题,以往人们曾多次做过观测研究,结论也较一致。在林后15H处,当风向与林带的交角由90°减小到67.5°时,对防护效果的影响不超过2％;当交角减少到45°时防护效果减低1倍多。大多数的结果证明,当风向偏角在±30°以内时,对防护效果的影响不大。并据此得出结论,主林带应与当地主害风方向垂直。 现在,农田防护林已经发展到了山、水、田、林、路综合治理,实现农田林网化,建立防护林综合体系的阶段。农田林网的营造,有赖于沟、渠、路、林、村(点)、桥的有机结合,全面规划。这样,问题就产生了。我省农田排灌沟、渠由于地形及习惯的原因,一般均呈东西、南北方向交错排列,而
With regard to the issue of forest belt protection in farmland shelterbelts, in the past many people conducted observations and studies, and the conclusions are more consistent. At 15h after forest, the effect on the protective effect did not exceed 2% when the angle between the wind direction and the forest belts decreased from 90 ° to 67.5 °; and the protective effect was more than double when the angle of intersection reduced to 45 °. Most of the results show that when the wind direction deviation within ± 30 °, little effect on the protective effect. According to this conclusion, the main forest belt should be perpendicular to the direction of the local host wind. Now, farmland shelter belts have been developed to the comprehensive management of mountains, water, fields, forests and roads, the realization of farmland network of shelterbelt, and the establishment of a comprehensive shelterbelt system. Construction of farmland forest network, depends on the ditch, canal, road, forest, village (point), the bridge of the organic combination of comprehensive planning. In this way, the problem arises. Irrigation ditch irrigation channels in our province, due to the topography and habit of reason, are generally something, north-south staggered, and