三江源区高寒草甸退化对土壤养分和土壤酶活性影响的研究

Effect of Typical Alpine Meadow Degradation on Soil Enzyme and Soil Nutrient in Source Region of Three Rivers

研究了三江源区高寒草甸退化对土壤养分和土壤酶活性造成的影响,结果表明:在极端环境下高寒草甸退化对土壤有机质和全氮含量的影响一致,随着退化程度的加重出现先升高而后降低的现象,重度退化阶段土壤表层含量降低,中下层土壤含量升高;全磷的含量先随着退化加剧降低,在重度退化阶段升高;退化导致土壤全钾含量降低。速效养分含量的变化也不相同:速效氮的含量在轻度和中度退化阶段降低,在重度退化阶段升高;速效磷的含量呈升高趋势;速效钾的含量先升高后降低。草甸退化使土壤脲酶和蔗糖酶活性出现了显著变化(P<0.05),脲酶活性在不同土层间差异显著(P<0.05),蔗糖酶没有表现出土体层次性差异;相关分析表明,高寒草甸的土壤酶活性与营养成分含量之间相关不显著。

The effect of alpine meadow degradation on soil enzyme and soil nutrient in source region of three rivers were studied. The results showed that the effect of degradation on the soil organic matter and total N were almost the same： the contents ascended first then descended, in heavily degradation stage the contents descended in the upper layer but ascended in middle layer and lowest layer; the contents of total P descended first with the degradation and ascended high in heavily degradation stage; the contents of total K descended with the soil degradation. The variance of available nutrient were different ： the contents of available N descended in lightly degradation stage and moderately degradation stage , and ascended in heavily degradation stage;the contents of available P was in a tendency of ascending ; the contents of available K ascended first then descended. The activity of Urase and Sucrase in different degradation stages showed significant variance（P〈0.05）;the activity of Urase in different soil layers were significant（P〈0.05）;Sucrase activity showed no significant variance in different soil layers. The activities of soil Urease and Sucrase had no significant correlation with soil nutrient.