放牧对小嵩草草甸土壤酶活性及土壤环境因素的影响

观测了放牧对高寒小嵩草草甸土壤酶活性及土壤环境因素的影响,结果表明:①随着放牧压力的增大,植被盖度、地上生物量、土壤有机质、全氮、硝态氮、全磷、有效磷、土壤水分明显下降,而地下生物量、土壤容重、pH及根土比呈现增大趋势,不同放牧处理间植物群落特征及土壤理化特性显示出明显的差异(P0.05);②纤维素分解酶、多酚氧化酶、脲酶、蛋白酶、碱性磷酸酶和蔗糖酶活性均随放牧压力增大而下降,只有过氧化氢酶以轻牧最高,各处理间上述土壤酶活性差异程度不同;③随着土壤深度的增加,土壤水分含量、地下生物量、根土比、土壤有机质及氮、磷养分等明显下降,而土壤容重和pH逐渐增大,且不同层次之间存在显著的差异(P0.05);④除过氧化氢酶和多酚氧化酶外,其它土壤酶活性随土壤深度的加深显著减小。

The impact of grazing on the activities of soil enzymes and soil environmental factors in alpine Kobresia pygmaea meadow

In order to determine the impacts of grazing on the soil enzyme activities and other environmental factors in alpine Kobresia pygmaea meadow,we investigated the activities of cellulase,polyphenol oxidase,urease,protease,alkali phosphatase,invertase and catalase,and the soil environmental factors.The results showed as follows: ①The vegetation coverage,above-ground biomass,soil organic matter,total nitrogen,NO₃^--N,total phosphorous,available phosphorous,water content decreased,while the underground biomass,bulk density,pH and root/soil ratio increased with grazing intensity.② The activities of most soil enzymes decreased with grazing intensity,while the catalase was higher in lightly grazing treatment than other treatments.③ The soil water content,underground biomass,root/soil ratio,soil organic matter and soil nitrogen and phosphorus decreased,while bulk density and pH increased with soil depth(P<0.05). ④ Except for catalase and polyphenol oxidase,the activities of the other soil enzymes decreased obviously with soil depth.⑤The analysis of variance indicated that the characters of plant community,soil physical and chemical properties showed significant differences(P<0.05),while only certain soil enzyme activities showed differences among different grazing intensity treatments.