翻耕补播对青藏高原疏勒河上游高寒草甸土壤可培养微生物数量的影响

Research on response characteristics of alpine meadow microbial population to tillage in the upstream regions of Shule River,Qinghai-Tibet Plateau

高寒草甸是青藏高原面积最大的草地类型,对全球生态环境的影响十分巨大。然而在外界干扰下,使得本身就很脆弱的高寒草甸发生了不同程度的退化。为探究翻耕补播对土壤微生物的影响,以疏勒河上游不同季节(4月、6月、9月)原生高寒草甸、退化草甸和翻耕补播草甸土壤为对象,研究了土壤可培养细菌数量的季节变化及其影响因素。结果表明:研究区域可培养细菌数量介于4.3×10^6~4.5×10^7CFU·g^-1之间,不同季节退化草甸与翻耕补播草甸土壤细菌数量均显著低于原生高寒草甸,且不同类型高寒草甸生态系统下可培养细菌具有明显的季节差异:原生高寒草甸生态系统下土壤细菌在6月生物量最高,4月最低;而退化草甸与翻耕补播草甸土壤细菌生物量并没有表现出明显的季节波动;相关分析表明,可培养细菌数量与土壤全氮、植被盖度及土壤含水量存在极显著正相关关系。研究发现,翻耕补播措施并没有恢复该区域微生物数量,研究结果对于认识高寒草甸生态系统的退化成因,判断恢复措施的有效性和合理性具有重要意义。

Under the influence of climate warming and human activities,the alpine meadow in Qinghai-Tibet Plateau has significantly degenerated,making scholars attach great importance to it.However,their influence on microorganism is still uncertain.This study regarded original ecological alpine meadow in upper reaches of Shule River in the northeastern Qinghai-Tibet Plateau,natural degeneration alpine meadow and artificial plowing and supplementing alpine meadow soil as the targets,and systematically researches on the influence of degeneration and plowing and supplementing on the quantity of microorganism in this area.The results showed that the quantity of bacteria which can be cultured in the study area varied between 4.3×10^6~4.5×10^7 CFU·g^-1,and bacteria,which could be cultured,have clear seasonal variations under different types of alpine meadow ecosystems:bacterial quantity reached the highest level in June and lowest in April under original ecological alpine meadow ecosystem,but it has no clear seasonal variations in natural degeneration and plowing and supplementing alpine meadow;What’s more,the quantity of bacteria which could be cultured in natural degeneration and plowing and supplementing alpine meadow were evidently less than original ecological alpine meadow.Related analyses demonstrated that what resulted in the phenomena mentioned above lies in the difference of soil physical and chemical properties and vegetation characteristics.Correlation analysis showed that soil bacterial quantity was significantly positively correlated with soil total nitrogen,vegetation cover and soil moisture.So it can be seen that measures of plowing and natural supplementing in this area do not recover the quantity of microorganism,and even less than degeneration meadow soil.The results provide data base for using microorganism to overview different types of alpine meadow ecological environment in Qinghai-Tibet Plateau.