均匀配置的两种仿真灌木林防风效应野外观测

建立灌木林是一种有效的防风固沙方法,灌木林空间配置是防护林体系研究与建设取得最佳效益的关键.应用两种仿真固沙灌木,建立株行距相等的均匀配置灌木林,观测林内与林前不同风速,比较其防风效能.结果表明:在风速为4.6～10.7 m·s^-1时,侧影面积为0.25 m²的无叶仿真灌木林比侧影面积为0.39 m²的有叶仿真灌木林防风效能低10%～20%.仿真固沙灌木林风速与高度变化关系呈指数函数关系,但在风沙流中拟合系数更高.仿真固沙灌木林空气动力粗糙度平均值是流沙地的5倍多,但不同风速下的粗糙度值差异较大.对相同配置的防风固沙林,调节灌丛结构可以提高其防风固沙效能.

Windbreak Efficiency of Two Types of Simulated Shrub Forest Equally Planted in Field

It is an effective method for controlling wind and fixing moving sand to establish shrub forest, and construction and configuration of windbreak forest is a key study aspect for enhancing function of windbreak shrub forest. Two types of windbreak shrub forest with equal spacing in the rows and between rows were established to observe wind velocity in forest and in front of forest and compare the wind break effect of forest configuration. The results showed that the cutdown ratio of wind velocity of simulated shrub forest without leaf with upwind projected area of 0.25 m² was less by 10%-20% than simulated shrub forest with leaves with upwind projected area of 0.39 m² at the wind velocity of 4.6-10.7 m·s^-1 with equal spacing in the rows and between rows. The wind velocity of two types of simulated shrub forest had exponent function relationship with height change, while that there was well fitting for the exponent function relationship over shifting sandy land. The roughness of simulated shrub forest was five times that of shifting sandy land, but it was different at different wind velocity. The windbreak efficienly can be increased by optimal configuration of shrub forest with equal spacing in the rows and between rows.