Changes in the activities of soil enzymes and microbial community structure at different degradation successional stages of alpine meadows in the headwater region of Three Rivers,China

Abstract

An analysis was carried out on the soil enzyme activities and the soil microbial community structure of alpine meadows in the headwater area of the Yellow River,the Yangtze River and the Lancang River at four successional degraded stages(NS:Normal Steppe,LD:Light Degradation,MD:Moderate Degradation,HD:Heavy Degradation)using the colorimetric method and phospholipids fatty acid(PLFA).1)The species and quantity of soil microbes did not reduce with degradation of the alpine meadow and they reached the highest level at MD.2)The soil microbial structure at MD was the most complex one among the four stages.3)The soil microbial diversity in the 0-10cm layer was richer than that at 10-20cm,which made the microbial community structure better adapted to the changes of ambient environment.4)The activities of all five enzymes decreased significantly(P0.05)with soil depth and the activity of alkali phosphatase decreased considerably as the alpine meadow degraded(P0.05).The maximum activities of protease and polyphenol oxidase appeared at MD,with the minimum in NS,but the activities of invertase and urease(P0.05)seldom changed in any of the four stages.Enzyme activities responded differently to changes of the ambient environment.Alkali phosphatase,protease and polyphenol were more sensitive than invertase and urease.5)There was a significant correlation between soil enzyme activities and soil microbes at successional degraded stages of the alpine meadow(P0.05).Soil enzyme activities and soil microbial community structure could be comprehensive indicators to show the stage of succession and the degree of degradation on the alpine meadows in the headwater areas of the three rivers.