塔里木河下游不同荒漠植被防风阻沙效应

Windbreak and sediment-keeping effects of different desert vegetation in lower Tarim River,in China

以胡杨、多枝柽柳、铃铛刺和黑刺4种天然荒漠植物为研究对象,对植株单株周围风速以及输沙量的变化进行了观测。结果表明,胡杨对地表风速和输沙量的防阻作用不明显,多枝柽柳、铃铛刺和黑刺灌丛对地表风速和输沙量的影响较明显;不同灌丛的迎风面2倍树高(TH)处的风速大于迎风面1TH处风速,输沙量大小与风速大小成正比;灌丛两侧1TH处的风速与输沙量大于迎风面1TH和2TH处风速与输沙量;背风面1TH处的风速最小,背风面风速达到一定距离后渐渐恢复原来的风速;背风面输沙量1TH处最小,距离越远越大;这4种植物的防风效益依次为多枝柽柳B1>胡杨A1>多枝柽柳B2>铃铛刺C1>黑刺D1>铃铛刺C2>黑刺D2>胡杨A2。

Wind speed around the single plant （ Populus euphratica, Tamarix ramosissima, Halimodendron halodendron, Lycium ruthenicum） as well as the change of sediment-transport were observed. It was discovered that the role of Populus euphratica was insignificant for decreasing surface wind speed, but the role of shrub was significant. The wind speed at 2 times the tree height was higher than that at the tree height in the windward side of different shrub, and sediment￣transport rate was in proportion to the wind speed. Wind speed and sediment transport at the tree height in two sides of shrub were higher than those at 2 times the tree height and at the tree height in the windward side of shrub. Wind speed was minimum at the tree height in the lee side of shrub, and the wind speed in the lee side gradually returned to original wind speed in a certain distance away from the shrub. Sediment transport was minimum at the tree height in the lee side of shrub but increased with the distance away from the shrub. The efficiency of wind prevention in these 4 species of plants were ranked downward as Tamarix ramosissima B1〉 Populus euphratica A1〉 Tamarix ramosissima B2〉 Halimodendron halodendron C1〉 Lycium ruthenicum D1〉 Halimodendron halodendron C2〉 Lycium ruthenicum D2〉 Populus euphratica A2.