乌兰布和沙漠不同结构防护林带的防风效能

On defending effects of different forest belt structures in Ulan Buh Desert

为对乌兰布和沙漠地区防护林建设提供理论依据,对乌兰布和沙漠几种典型结构和配置的防护林带进行风速观测,结果表明：其防风效益与林带高度、结构、疏透度等因子有关,稀疏型林带防风效果最佳,平均为41.37%,疏透型次之,为29.58%,通风型防风效果最差,为23.92%。林带防风效能较好的疏透度为40%~50%,随着林带总平均疏透度的增加,防风效能显著降低。分层疏透度不同也直接影响防风效果,因此,林带结构应以稀疏型为主,林带总平均疏透度控制在30%~50%,分层疏透度应控制在林冠层30%~50%,林干层50%。

According to observations on wind velocities of different shelterbelts in Ulan Buh Desert, the paper shows that the defending effect varies with forest belt structure, height and porosity. Wind defending effect of sparse structure shelterbelt is the best, which is41.37%, porous structure takes the second place, 29.58%, and ventilation structure is the worst, 23.92%. Shelterbelt with a porosity of 40%～50% has the best wind defending effect. With the increase of porosity, the defending effect decreases remarkably. So the structure should be sparse with a porosity of 30%～50%, and the porosity of forest canopy should be 30%～50% and the porosity of trunk, 50%.