高寒沙区植被人工修复与种子植物物种多样性的变化

Changes of Plant Species Diversity in the Process of Human-Induced Vegetation Restoration in Sandy Lands of Qinghai-Tibet Plateau

以 195 8年以来青海省沙珠玉治沙站流沙治理实验为基础 ,研究了高寒沙区植被人工修复过程中种子植物物种多样性变化的规律。结果表明 :人工治理初期沙地植物群落的物种丰富度、Shannon_Wiener指数和Pielou均匀度指数不断增大 ,并逐渐达到最大值 ;但是随着恢复的继续进行 ,赖草会逐渐占据优势 ,上述三项指数降低。设置人工沙障后削弱了沙丘表面风沙活动对植物定居的不良影响 ,促进植物物种顺利定居并启动植被的恢复重建。

Sand control and human_induced vegetation restoration is very important to improve local environments and achieve sustainable development in Qinghai_Tibet Plateau. Since 1958, a series of experiments to combat desertification have been conducted in Shazhuyu of Gonghe Basin, Qinghai Province. In this study, several indices of plant species diversity, increased rapidly after establishing sand barriers. At the earlier phase of artificial sand fixation vegetation, all these indices reached a maximum, and then decreased because of the overwhelming dominance of Leymus secliumus population in late succession. It indicated that on shifting sand dunes of Qinghai_Tibet Plateau, persistent erosion and sand drifting caused by strong winds are probably the limiting factor or bottleneck for plant species to survive shifting sand dunes. When mechanical and biological sand barriers are established, wind erosion and sand drifting can be weakened dramatically, which created relatively favorable conditions for native plant species to survive there and then accelerated the vegetation restoration. Total cover and cover of Leymus secliumus which is dominant in best_restored vegetaion are the most sound indices to evaluate degree of vegetation restoration, instead of plant species diversity which rose at the beginning of restoration but decreased reversely after a short time and dropped to bottom in best_restored vegetation. According to intermediate disturbance hypothesis, we argue that the low species diversity maybe results from the overwhelming dominance of Leymus secalimus that can exclude some other plant species.