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关于农田防护林的林带走向问题,以往人们曾多次作过观测研究,结论也较为一致。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%;当交角减小到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。
With regard to the issue of forest belt protection in farmland shelterbelts, people have conducted observation and research many times in the past and the conclusions are more consistent. At 15h behind the forest, the effect of protection did not exceed 2% when the angle between the wind direction and the forest belts decreased from 90 ° to 67.5 °. When the angle of intersection was reduced to 45 °, the protective effect was more than doubled. 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.