江河源区人工草地植物群落和土壤酶活性变化

Changes in Plant Communities and Soil Enzyme Activities of Artificial Grasslands in Headwater Areas of the Yangtze and Yellow Rivers

通过研究江河源区不同建植年限人工草地植物群落特征、土壤理化性状和6种土壤酶活性,分析人工草地建植年限与土壤酶活性的关系.结果表明:随着人工草地建植年限的增加,植物群落的数量特征多呈高—低—高、杂类草生物量低—高—低、莎草生物量增加的趋势;土壤养分变化为高—低—高、容重为低—高—低、pH下降的趋势;土壤脲酶、转化酶、纤维素酶、碱性磷酸酶活性均呈高—低—高的变化趋势,蛋白酶活性呈逐渐上升而多酚氧化酶活性呈逐年下降的趋势.人工草地不同建植年限之间,6种土壤酶的活性显示出明显的差异性.逐步回归分析表明:土壤酶活性与植物群落的数量特征、土壤理化因子之间存在不同程度的相关关系.植物的物种数、高度、地下生物量及土壤湿度对大多水解酶类表现出直接的正效应,容重和pH对所选的多数酶活性显示出直接的负效应.各种环境因子之间相互调节,通过直接或间接的方式控制着土壤酶活性的大小.

The changes in plant communities and soil enzyme activities of artificial grasslands with different cultivation ages were investigated in the headwater areas of the Yangtze and Yellow rivers in China.With the increase in cultivation ages,the abundance of most plant communities and soil nutrients changed in a high-low-high pattern,i.e.,＂V＂ pattern,while the forb biomass and soil bulk density in an adverse pattern.The sedge biomass increased gradually,but soil pH presented a decreasing trend.All enzyme activities presented obvious differences among the grasslands with different cultivation ages.The activities of urease,invertase,cellulase and alkaline phosphatase changed in a ＂V＂ pattern.The protease activity ascended,while polyphenol oxidase activity descended with ageing.Stepwise regression analysis indicated the correlations at different degrees between enzyme activities and plant community and soil properties.The species number,plant height,underground biomass and soil moisture have direct positive-effect on the activities of most hydrolase,while bulk density and pH have direct negative-effect on the activities of most selected enzymes.All soil enzymes were regulated by environmental factors in direct or indirect paths.