河西绿洲边缘积沙带的生态意义

半个多世纪的防沙治沙,在甘肃河西绿洲边缘上风向形成了一条积沙带。积沙带作为防沙治沙的副产物,具有怎样的生态功能,有何生态意义?通过全面考察河西绿洲边缘积沙带并运用21个样点资料进行了分析。结果表明:1)积沙带作为绿洲边缘防沙固沙的副产物,其自身也具有防风阻沙的功能,积沙带的形成有利于绿洲边缘的防风阻沙。2)高度是表征积沙带防御风的功能的一个重要指标,积沙带越是高大,防御风的范围就越大。3)目前,河西绿洲边缘积沙带处于发育状态。只要控制了积沙带就能有效控制流沙侵入农田。今后应将绿洲边缘防沙治沙的重点放在积沙带上,尤其是积沙带的沙脊线上,而对荒漠-绿洲过渡带(阻沙带)实行封育,无需采取其他投入措施,这样就可以大面积压缩实施人工措施的范围,大大降低防沙治沙的资金投入,提高防沙治沙的投资效益。

The ecological significance of accumulated sand-belts along the oasis edge of Hexi of Gansu

In the desert area in Hexi of Gansu, China, an accumulated sand-belt formed along the oasis edge, especially at the upwind places, during the process of desert control. The accumulated sand-belt took over 50 years to form and is a byproduct of combating desertification from afforestation and barriers-setting. In this study, we conducted a comprehensive analysis of the accumulated sand-belts along the Hexi oasis edge as well as data from 21 samples to determine the ecological functions and significance of the accumulated sand-belts. The results showed that: 1) The accumulated sand-belt, as a byproduct of combating desertification along the oasis edge, has a function of blocking wind and sand. 2) Height is an important factor determining the wind-blocking function of an accumulated sand-belt. The taller and bigger the accumulated sand-belts are, the wider the scope of wind-blocking. 3) Currently, the accumulated sand-belt along the Hexi oasis edge is still in the developmental stage. As long as it is under control, the invasion of moving sands into nearby farmlands will be minimal. In the future, the emphasis of desert control should be focused on the accumulated sand-belts, especially on the sand ridgeline of the accumulated sand-belt. The desert-oasis ecotone (resistive sand-belt) should be fenced, without the need for other containment measures. In this way, areas for implementing artificial measures for desert control will be greatly decreased, which will be helpful in reducing the funds invested and in improving the investment returns in combating desertification.