河北省坝上地区牧场防护林的防风效能研究

目的]揭示河北省坝上地区御道口牧场防护林林带的防风效能,为牧场防护林建设提供理论依据。方法]以樟子松防护林林带为研究对象,运用空间多点观测法观测。结果]当旷野风速为3.84m/s时,在林后1(H为林带平均高度)H处,风速最小,同时防风效能最大,但随着水平距离的增加风速在逐渐升高而防风效能呈逐渐下降趋势。旷野风速越大,林带防风效能增大,有效防护距离变大。当旷野风速为5~6级时,在林内,1H,5H处的防风效能最好,防风效能范围为67.97%~94.27%。不同垂直高度上防风效能的变化趋势由大到小为:30,50,150,300cm,风速的分布规律变化趋势与防风效能正好相反,由大到小为:300,150,50,30cm。结论]牧场防护林林带后的1~10H区域是林带的最佳保护区和作用范围,其中林后1H的防风效能最好,但会随着风速和垂直高度的变化而有一定的差异。

Windbreak Efficiency of Pasture Shelterbelt in Bashang Area of Hebei Province

Objective] Studying the windbreak efficiency of shelterbelt in Yudaokou pasture in Bashang Area of Hebei Province to provide a theoretical basis for the construction of pasture shelterbelt.Methods] Taking The Pinus sylvestris shelterbelt as the research object, the spatial multi-point observation method was applied.Results] When the desert wind speed was 3.84 m/s, the wind speed was the smallest at 1 H(H stands for the average hight of the forest shelterbelt) after the forest, and the wind efficiency was the most, but with the increase of the horizontal distance, the wind speed was gradually increased and the wind efficiency gradually decreased. The greater of the desert wind speed, the higher of the windbreak efficiency, and the larger of the effective protection distance. When the wind speed level in the open field was 5~6, in the forest, 1 H and 5 H of the wind protection efficiency were the best, and the wind efficiency range was 67.97%~94.27%. Windbreak efficiency at diffent vertical heights ranked:30, 50, 150 and 300 cm, and the rank of wind speed distribution was opposite to that of windbreak.Conclusion] After the pasture shelterbelt of the 1 H to 10 H area is the best protection area and the action scope of the forest belt. The windbreak efficiency of the post forest 1 H is best, but it will vary with the change of wind speed and vertical height.