甘肃玛曲高寒草原沙化草地植物多样性研究

玛曲高寒草原是青藏高原的重要组成部分和黄河上游地区的主要水源涵养区,高寒草地沙质荒漠化和水土流失已严重威胁到青藏高原生态系统的安全。通过重要值理论和多样性理论对玛曲高寒草原不同程度沙化草地植被群落植物多样性进行研究,为治理流沙和草地生态系统恢复提供理论依据和技术支撑。结果表明:①随着沙化程度的加剧,高寒草原生态系统向高寒沙质荒漠生态系统转化,群落以苔草+早熟禾群落→苔草+防风+嵩草群落→球穗莎草+防风+苔草群落→赖草+虫实+苔草+防风群落的方向演替。大多数高寒草地物种退出群落,而适应沙质荒漠的物种逐渐占据优势地位;②群落丰富度指数、多样性指数急剧下降,均匀度指数呈现先增加后减小的趋势,在中度沙化草地达到最大,而群落优势度逐渐增加,在重度沙化草地增加明显;③潜在沙化草地Whittaker指数远小于沙化草地,而不同沙化草地之间Whittaker指数的差异不显著。潜在沙化草地相异性系数CD和共有度指数CP与沙化草地差异性显著,而且随着沙化程度的加剧,差异越显著。所以应加强潜在沙化草地的保护措施,而对沙化草地应采取流沙治理措施进行生态修复,防止草地沙化的加剧和蔓延。

Study on Plant Diversity of Different Desertification Lawn in Maqu Alpine Grassland

As the important composition of Qinghai-Tibet Plateau and the mainly water conservation district of the upstream of Yellow River,the sandy desertification and water-soil loss of Maqu alpine grassland had seriously threat the ecosystem of Qinghai-Tibet Plateau and water conservation of Yellow River.Based on important value and plant diversity,the plant diversity of different sandy desertification vegetation in Maqu alpine grassland was studied.The result showed：1） With the intensification of sandy desertification,the alpine grassland ecosystem was tending to the alpine sandy desertification ecosystem,the communities succession were the community of Carex moorcroftiii ＋ Poa annua→the community of Carex moorcrofiiii ＋ Saposhnikovia divaricata ＋ Kobresia robusta → the community of Cyperus difformis ＋ Saposhnikovia divaricata ＋ Carex moorcrofiiii → the community of Leymus secalinus ＋ Carex moorcrofiiii ＋ Saposhnikovia divaricata.The many species of alpine grassland were disappeared,but the species which adapted to sandy desert were gradually occupying the dominant position.2） The species richness index and plant diversities were rapidly declined,the evenness index was increased firstly and decreased lastly,and its value was largest in the community of moderately desertification grassland,but the dominant value of community was gradually increased and its value was significant increased in the community of severe desertification grassland.3） The Whittaker index of potential desertification grassland was far less than the index of sandy grassland,but no significant difference among the communities of sandy desertification grassland.The difference of CD and CP were signification between the potential desertification grassland and sandy desertification grasslands,and the difference was more signification with the increasing of sandy desertification.So the potential desertification grassland was protected,but the sandy desertification grasslands must be repaired by sand control measure in order to prevent desertification exacerbating and spreading.