柠条锦鸡儿不同植被类型遮蔽效应的风洞研究

A Wind Tunnel Study of the Shelter Effect of Different Vegetation Patterns of Caragana korshinskii

防风是干旱半干旱地区减少风蚀的重要措施。在风洞中进行了一系列试验,以评估模拟柠条锦鸡儿不同植被类型(均匀、随机和集群)的防风有效性。均匀模式提供了较好的遮蔽效果,在密度为50%时效果最佳。随着行数的增加和带状间距的减小,保护区面积和减风率增大,下风向最小风速减小。最小风速(X_(min))的位置在单排、两排和三排带上相似。在背风距离植被较近处(≤5 H,H表示了植株的高度),高密度植被格局效率大于多排带,与多带防护林相似,背风距离>5 H则相反。单行带效果最差,带间距4 H的双带防护林效果最好。多带防护林下风向风速较低,遮蔽长度较长,可为干旱半干旱地区设计防风林降低风速、控制风蚀提供参考。

Windbreaks are important measures for reducing wind erosion in arid and semi-arid areas. A series of experiments were conducted in a wind tunnel to assess the effectiveness of different vegetation patterns(uniform,random, and cluster) of simulated Caragana korshinskii stands on wind speed. The uniform pattern provided a better shelter effect and was optimal at a density of 50%. The protected area and the wind reduction ratio increased and the downwind minimum wind speed decreased with an increase in the number of rows and a reduction in the belt's spacing. The locations of minimum wind speed(X_(min)) were similar in arrangements with single-, two-and three-row belts. At the leeward distance close to vegetation(≤5 H, where H is the height of the plants), the efficiencies of vegetation patterns with high densities were greater than those of multiple-row belts and similar to those of multiple-belt shelterbelts;but at the leeward distance >5 H, the relationship was reversed. The single-row belt was the least effective, and the double-belt shelterbelt with belt spacing of 4 H was the most effective pattern. Multiple-belt shelterbelts had a lower downwind wind speed and a longer sheltering length than the other patterns, and so it is recommended windbreaks designed to reduce wind speed and control aeolian erosion in arid and semi-arid areas.