青藏高原人工草地土壤微物量碳及酶活性动态变化特征

Dynamic changes of soil microbial biomass carbon and soil enzyme activities in alpine artificial grasslands

在青海省三江源地区不同高寒人工草地选取人工建植垂穗披碱草、星星草、冷地早熟禾草地为研究对象,探讨不同建植年限(2 a、4 a)人工草地土壤微生物量碳及土壤脲酶、碱性磷酸酶、硝酸还原酶在生长季内(6-9月)的动态变化特征,了解土壤微生物量碳和土壤酶活性之间的相互关系,为人工草地生态系统的管理提供参考依据.结果表明:不同建植年限3种人工草地土壤微生物量碳均呈显著季节变化;同一土壤深度,垂穗披碱草、星星草和冷地早熟禾人工草地的土壤微生物量碳差异显著;同一人工草地、不同酶活性随生长季在一定范围内波动,具有显著的季节变化特征,不同人工草地同一土壤酶活性的季节变化不同;高寒人工草地土壤微生物量碳及其酶活性不仅受土壤温度、土壤水分和气温等的影响,还受牧草种类、建植年限、生长月份及其交互作用的影响;不同人工草地土壤微生物量碳与土壤酶活性呈显著相关关系,不同酶的活性之间也存在显著的相关关系.

Artificial grassland of Elymus nutans,Puccinellia tenuiflora and Poa crymophila were selected as the research objects in different alpine artificial grasslands in the Sanjiangyuan Area of Qinghai Province.Soil microbial biomass carbon(SMBC)and soil enzyme(urease,alkaline phosphatase,nitrate reductase)activities were analyzed aiming to reveal their growth season(June-September)dynamic characteristics and the relationships between the SMBC and soil enzyme activities.This study could provide a reference for the restoration and management of degraded alpine grassland ecosystem.The results indicated that the content of SMBC in divers aged artificial grasslands varied observably during the growing season.Grassland cultivated Elymus nutans was more conducive to the accumulation of SMBC than Puccinellia tenuiflora and Poa crymophila grassland.The activities of soil urease,alkaline phosphatase and nitrate reductase in alpine artificial grasslands fluctuated in a certain range during the growing season,i.e.having significant seasonal variations.The same soil enzyme activity in different artificial grasslands was also diverse.The SMBC content and soil enzyme activity was not only significantly affected by soil and climate factors such as soil temperature,soil moisture and air temperature,but also by grass species,cultivation periods and growth months as well as their interactions.A correlation analysis showed that there was a obvious correlativity between SMBC and different soil enzyme activities in the alpine artificial grassland,and there also existed a marked significant correlation between different soil enzyme activities.