绿洲——荒漠交错带活化沙丘的植物群落特征分析

以民勤绿洲-荒漠交错带活化沙丘上的植物群落为对象，研究了活化沙丘不同部位的沙地植物群落物种组成、结构和多样性的变化。研究结果表明:从活化沙丘的下部、中部、丘顶，到背风坡的中部、下部，再到丘间低地，每一个生境对应着不同的群落类型。各部位不仅植物种类和数量存在差异，而且群落结构差异明显，其中丘顶为一年生草本植被构成，而丘间低地处只有灌木。群落物种多样性与相似性指数表明，从沙丘下部到丘顶再到丘间地，生态因子的差异对物种的分布格局产生了影响，从而导致了群落结构和功能发生了变化。活化沙丘植被简单，退化严重，需加强保护，防止继续退化。

Analysis on Vegetation Characteristics of Activating Sanddunes in the Oasis-desert Ecotone

The vegetation communities of activating dune in the Minqin oasis-desert ecotone were investigated by a conventional way for researching the plant species structures and characteristics in different position of the dune. The results showed that there is a different plant community type in each position of the activating dune from low,midst,dune tops and midst, low of slope depressions and sandy land among the dunes. The differences of plant species and quantity had exist, also the variance of plant communities obviously. There is only annual grass species on dune tops, but shrubs on sandy land. The bio-diversity and the similarity index of communities showed that the differenee of ecological factors not only affected the distribution patterns of species, but also changed the structures and functions of plant communities. The vegetations of these activating sanddunes are simple and suffer degeneration serious, then need enhanced protection methods to prevent sand dunes from becoming mobile.