腾格里沙漠西南缘植被季节变化及风沙活动

Seasonal Vegetation Change and Sand-wind Activity in Southwest Fringe of Tengger Desert

腾格里沙漠西南缘沙区,3种植被条件下的盖度四季波动情况为：在林带背风面封育区25.89%～35.35%,封育区19.4%～29.39%,流沙区11.39%～16.05%之间;各季节植被盖度表现为秋季〉夏季〉春季〉冬季,其中,流沙区植被盖度春季增幅最大,旱季降幅最小,而林带背风面封育区则雨季增幅最显著,封育区次之。流沙区草本植物株（丛）数比例从春季开始近似线性增加,旱季变缓,雨季又有所增加,8月底至9月上旬达最大值,灌木植物比例则相反;封育区和林带背风面封育区草本植物株（丛）数比例变化相似,均为春季迅速上升,旱季下降,雨季显著增加,9月底达最大值,灌木植物相反。流沙区因植被稀疏,牲畜采踏,植被难恢复,裸露地面风沙流活动强烈,沙丘前移;封育区植被盖度较大,形成了比较稳定的自然生态植被区域;林带背风面封育区则在多层防护林防护下,区域内风速低,植被盖度大,枯枝落叶多,普遍有1～1.5 mm厚的结皮,形成了更加稳定的生态环境。试验研究表明：在当地降水条件下,只要在沙漠边缘建立足够的封育区,禁止或减少人为活动,自然植被恢复,可大大降低风沙活动,遏制沙漠前移,实现当地的生态可持续发展。

The vegetation coverage of three types plots at southwest fringe of Tengger Desert in four seasons changed from 25.89% to 35.35% at enclosure plots of shelterbelt leeward, 19.4% to 29.39% at enclosure plots, and 11.39% to 16.05% at sand open plots, showing plant coverage was the biggest increasing in Spring and the smallest decreasing in dry season at sand open plots, the most remarkable increasing at enclosure plots of shelterbelt leeward, and medium at enclosure plots in rainy season. The ratio of grass plant number to total plant number at sand open plots increased steeply in Spring, flat in dry season and remarkably in rainy season, and the biggest value occurred in the late Aug. to early Sep. ; The ratio of shrub plant number to the total ones was opposite. The ratio of grass plant number to the total was similar at the two types of enclosure plots, it increased in Spring, decreased in dry season and remarkably increased in rainy season, the biggest value occurred in late Sep. ; The ratio of shrub plant number to the total ones was oppo- site. In sand open area, sand-blown activity is frequent and intense due to rare vegetation and overgrazing; In enclosure area, a stable natural eco-vegetation area has been formed originally; In enclosure area of shel- terbelt leeward, there are low wind speed, larger plant coverage and usual soil crust about 1 ～ 1.5mm, which has formed a more stable eco-environment. The stored and realize sustainable development under local man activity or avoiding grazing in this area. experiment showed that the eco-vegetation can be reclimate through sandy land enclosure and limiting human activity or avoiding grazing in this area.