高寒草甸退化对优势物种根际土壤微生物量及酶活性的影响

Effects of alpine meadow degradation on microbialbiomass and enzyme activities in rhizospheresoil of dominant species

摘要:

以祁连山东缘的4个不同退化程度(未退化、轻度退化、中度退化、重度退化)高寒草甸为研究对象,测定分析了高寒草甸退化对优势物种和土壤理化性质的影响,以及不同退化程度优势物种对根际土壤和非根际土壤中3大类微生物的数量、微生物生物量(碳、氮、磷)的含量以及酶活性的影响。结果表明:(1)随高寒草甸退化程度的加剧,植物群落多样性呈下降趋势,土壤中有机碳、全氮、全磷和速效磷的含量呈逐渐降低的趋势;(2)随退化程度的加剧,根际和非根际土壤中3大类微生物的数量呈逐渐降低的趋势,并且不同退化程度下根际和非根际土壤中微生物的数量均表现为,细菌＞放线菌＞真菌;(3)随退化程度的加剧,根际和非根际土壤中微生物生物MBC,MBN和MNP的含量和土壤蔗糖酶、蛋白酶、脲酶、过氧化氢酶的活性均呈逐渐降低的趋势,并且土壤中微生物生物量的含量和土壤酶的活性均表现为根际土壤高于非根际土壤。

Abstract:

To explore the effects of changes in dominant species on soil enzymes and soil microbial characteristics during the degradation of alpine meadows.In this study,we used four different degrees of degradation (Non-degraded,Light-degraded,Moderate-degraded and severely-degraded grasslands) alpine meadows in the Qilian Mountains of the northeastern were chosen as the research area.Characteristic changes of the physicochemical properties of dominant species and soils,the number of three major types of microorganisms in rhizosphere soil and non-rhizosphere soils of dominant species with different degrees of degradation,microbial organisms the amount of carbon (nitrogen,phosphorus) and the effect of enzyme activity were determined and analyzed in alpine meadows under different degrees of degradation.The results showed that: (1) With the increase of the degradation degree of alpine meadow,the diversity of plant community showed a downward trend accompanied by the change of dominant species,while the content of organic carbon,total nitrogen,total phosphorus and available phosphorus in soil gradually decreased.(2) With the increase of degradation degree,the number of three types of microorganisms in rhizosphere and non-rhizosphere soils gradually decreased,and the number of microorganisms in rhizosphere and non-rhizosphere soils under different degrees of degradation showed that bacteria＞actinomycetes＞ fungi.(3) With the increase of degradation degree,the contents of microbial biomass (MBC,MBN,MNP) and the activities of soil enzymes (sucrose,protease,urease,catalase) in rhizosphere and non-rhizosphere soil gradually decreased,and the content of microbial biomass and soil enzyme activity in the soil were recognized as rhizosphere soil was higher than non-rhizosphere soil.The results of this study provide new ideas for the interaction between plants and soil microbes,and provide a scientific basis for vegetation restoration in ecologically fragile areas.