青藏高原高寒草甸退化对草地群落多样性及土壤特性的影响

Effects of Alpine Meadow Degradation on the Grassland Communities Diversity and Soil Properties on the Tibetan Plateau

为了明确青藏高原高寒草甸退化对草地植被多样性及土壤特性的影响,通过调查甘肃省甘南藏族自治州碌曲县、夏河县和合作市3个地区不同退化程度(轻度退化、中度退化和重度退化)的高寒草地的植被情况,分析其物种多样性及优势种,并采集土壤样品,测定其全氮、全磷、全钾、土壤pH值、全盐、容重、孔隙度、粒径等理化性质,土壤脲酶、蔗糖酶、过氧化氢酶和碱性磷酸酶等4种酶活性,以及细菌、放线菌和真菌等微生物数量。结果表明:随着退化程度的加深,碌曲县、夏河县高寒草甸物种多样性呈降低趋势,而合作市轻、中度退化草地的多样性较高,重度退化草地最低,同时,植被的高度、盖度及草产量降低;土壤全氮、全磷、全钾、孔隙度及粉粒总体呈降低趋势,土壤pH值、全盐、容重、黏粒及砂粒呈升高趋势;土壤脲酶、蔗糖酶活性降低;土壤细菌、放线菌数量降低,真菌数量升高。

The study aimed to clarify alpine meadow degradation effects on the grassland communities diversity and soil properties on the Tibetan Plateau by investigating vegetation conditions and analyzing the community diversity and dominant species in three areas in Gansu Province(Luqu County,Xiahe County,and Hezuo City of Gannan Tibetan Autonomous Prefecture)under different degradation(light,moderate and severe degeneration).Soil samples were collected to determine the contents of total nitrogen,total phosphorus,total potassium,and pH value,total salt,bulk density,porosity,particle size,enzyme activities(urease,sucrase,catalase,and alkaline phosphatase),and the number of bacteria,actinomycetes,and fungi.The result showed that the species diversity gradually decreased with the degradation of alpine meadows in the Tibetan Planteau.In addition,the vegetation height and coverage,grass yield,total soil nitrogen,phosphorus,potassium,porosity,and silt decreased,but soil pH value,total salt,bulk density,clay,and sand went opposite.For soil enzyme activities,urease and invertase activities decreased.For microorganisms,the number of soil bacteria and actinomycetes decreased while that of soil fungi increased.