河西走廊沿沙防护林演变形式与积沙带稳定性研究

Evolution Form of Protection Forest at Oasis Fringe in Hexi Corridor and Stability of Accumulated Sand-belts

文章通过对甘肃河西地区沿沙绿洲边缘防风固沙林演变方式及其后期形成的积沙带植被结构与稳定性的调查分析,研究认为:数十年来,随内陆河上游来水减少,固沙林内水分供给能力的减弱,植物种类由初建乔灌木逐步被低矮的耐旱灌丛和逐水草本取代,随之形成了具有阻挡流沙越境的积沙带;积沙带的形状与积沙规模取决于当地风沙侵袭强度,防护林建植位置、时间,农田经济利用所采取的维护程度,带上不同部位着生植被借助农田渗余水的补给,处于相对稳定状态;沿沙防风固沙林建设及其演变形成的积沙带,对越境流沙起到了重要阻积作用,是目前维护沿沙绿洲长期安全重要屏障,应采取必要措施保护与利用。

Evolution modes of windbreak and sandbreak forests at oasis fringe in Hexi Corridor in Gansu Province,plant structure of accumulated sandy-belt and its stability were investigated.Result shows that with reduction of runoff of upper reach in endorheic river and weaken of water supply capacity,plant species changed originally from drought-resistant shrubs to low and seasonal grasses gradually,and formed some accumulated sandy-belts which can stop transboundary of shifting;the forms and scales of the sandy-belts were controlled by maintenance extent taken by sand erosion,planting position of protection forest,time,economic use of farmland;plant was supplied by water seepage in farmland,being in a relatively stable state;accumulated sandy-belts prevent most wind sand and play the role of oasis fringe windbreak forests are still protected oasis long-run safety,some maintenance steps should be supported to the windbreak forests.