摘要:高寒草原作为青藏高原区主要的草地类型，在全球碳、氮循环、生物多样性维护、水土保持、畜牧业发展等方面发挥着重要的作用。在青海省果洛州玛多县高寒草原选取5块不同退化程度的样地，调查植物功能群组成和土壤理化性质，并采用多元排序法分析不同退化程度下植物功能群组成与土壤因子的关系，以期明确高寒草原功能群组成对草原退化的响应。结果表明：（1）禾本科功能群丰富度和重要值均随退化程度增加呈先增后降趋势，盖度表现为降低趋势；杂类草功能群的丰富度、盖度和重要值均随退化程度增加呈先增加后降低的趋势。而杂类草功能群的相对重要值随退化程度增加而增加。（2）土壤有机质含量随土层深度的增加而降低；随退化程度加剧，土壤有机质和全氮呈降低的趋势。（3）随退化程度加剧，0-30 cm各土层深度的容重均增加，土壤通气孔隙度降低。（4）各功能群重要值与土壤通气孔隙度呈正相关关系，与土壤容重呈负相关关系；通过冗余分析，草地退化首先影响土壤物理属性进而影响草地功能群组成。



Abstract:Alpine steppe is one of the dominant grassland types on Tibetan Plateau. It plays an important role in global carbon cycle, nitrogen cycle, biodiversity conservation, soil and water conservation, and animal husbandry development. This study selected five sampling plots with different degradation levels on the degraded alpine steppe in Maduo county, Guoluo Prefecture, Qinghai Province. The composition of plant functional groups and soil physical and chemical properties were investigated in the sampling plots. We used the multivariate analysis to analyze the relationship between plant functional composition and soil physical and chemical properties. The results showed that: (1) with the steppe degradation increasing, the richness and the important value of Gramineae functional group increased firstly and then decreased, but the coverage of Gramineae functional group was decreasing. The richness, coverage and important value of forbs functional group increased firstly and then decreased, while the important value of forbs functional group was increasing. (2) The content of soil organic matter was decreasing with the soil depth increasing. The content of soil organic matter and total soil nitrogen were decreasing with the steppe degradation increasing. (3) As the steppe degradation increasing, the soil bulk density, soil porosity at the depth of 0―30 cm were increasing, while the soil moisture content decreased firstly and then increased. (4) The important value of each plant functional group was positively correlated with soil porosity and negatively correlated with soil bulk density. Through redundancy analysis, the grassland degradation firstly affected soil physical properties and then affected the composition of plant functional groups.





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