【作者】 熊金波； 孙怀博； 彭飞； 林先贵； 薛娴； 褚海燕；

【Author】 Xiong jinbo,Sun Huaibo,Peng Fei,Lin Xiangui,Xue Xian,Chu Haiyan (1.Institate of soil,Chinese Academy of Sciences Nanjing,210008; 2.Coed and Arid Regions Enviromecfal and Enginering Research Institude Chinese Academy of Sciemces)

【机构】 中国科学院南京土壤研究所； 中国科学院寒区早区环境与工程研究所；

【摘要】 高海拔高寒草甸土壤生态系统正经历着高于全球平均增温幅度的气候变化,由于这些寒冷地区的微生物代谢活性主要受到温度的限制,因此对环境的扰动非常脆弱,对增温十分敏感。长期以来,增温对土壤理化性质和植物初级生产力、光合作用等的影响及作用机制已进行了较深入的研究;相比而言,土壤微生物群落结构和多样性如何应对气候变化却不甚明了,也存在着争议,如:微生物是通过群落结构的改变还是生理功能的适应来应对气候变化;这种变化需要增温处理多长时间后发生以及这种改变能够持续的时间。微生物参与主要的地球化学循环,对生态系统如何应对气候变化起到主导作用,因此,研究微生物群落对增温的响应和反馈,将有助于准确评估和预测全球气候变化对生态系统功能和稳定性的影响。本实验中,我们利用454高通量测序技术研究了青藏高原一高寒草甸土壤在增温处理(2个增温幅度:对照、增温1℃和2℃,各五个重复)16个月后对细菌群落的影响。实验结果表明:短期的增温处理显著地改变了土壤细菌的群落结构,而多样性和丰富度没有明显改变。具体而言,来自Acidobacteria(酸杆菌)和Bacteroidetes(拟杆菌)的成员丰度增加,而来自Actinobacteria(放线菌)的成员丰度降低来应对增温;主要是Actinobacteria和Alphaproteobacteria(α-变形菌)造成了增温和对照处理间细菌群落的差异,这些变化模式可能作为应对气候变化的敏感指标。此外,Alphaproteobacteria和Acidobacteria的比值作为土壤中可利用营养物质的指示指标,在增温处理下显著(P=0.037)增加,很可能是导致土壤在增温条件下呼吸速率增加的主要因素。Mantel分析结果表明细菌群落结构的变异与土壤和植物性质显著相关;群落变异分配分析结果表明增温只解释了7.15%的细菌群落变异,而土壤理化性质和植物性状解释了更多的变异,因此增温可能主要是通过改变土壤和植物的特征,间接地影响和作用于土壤微生物群落。综上所述,细菌的群落结构能够对短期的增温做出快速的响应,而主要细菌门类丰度的改变可能对生态系统功能产生潜在影响。更多还原

【Abstract】 High altitude alpine meadow is experiencing much greater than average increases in surface temperature,where the microbial activities are primary controlled by temperature,thus,it is highly vulnerable to the ongoing climate change.The stimulating effects of warming on plant and soil variables have been established,while its impacts on the diversity and structure of soil microbial communities remain elusive and controversial.For example,it is uncertain the microbial communities respond to warming through physiological adoptions or changes in community composition,and when such changes occurred and sustained? Microorganisms mediate important biogeochemical cycles of carbon and nitrogen, control the response of terrestrial ecosystem to global warming.Therefore,a robust evaluation and prediction of future warming requires mechanistic understanding of how warming affects microbial community composition.In this study,using barcode pyrosequencing technique,we investigated soil bacterial community structures and diversities after 16 months field exposure to warming(two warming treatments:elevated 1℃and 2℃,each with five replicates) in an alpine meadow of Tibetan Plateau. Short-term warming dramatically altered the structures of soil bacterial community,but the richness and diversity were unaffected.Specifically,the abundance of populations derived from phyla Acidobacteria and Bacteroidetes significantly decreased,while Actinobacteria increased in response to warming.The members affiliated to Actinobacteria and Alphaproteobacteria mostly contributed to the differences between ambient and warming conditions.Additionally,the ratio of Alphaproteobacteria to Acidobacteria is indicative of soil nutrient availability,was significant(P = 0.037) increase under warming soils,this change may contribute to the increased soil respiration in response to warming.Mantel tests indicated that the variations of bacterial community structure were closely correlated with soil and plant properties. Variance partitioning analysis(VPA) showed that warming contributed minor(7.15%) to bacterial community variation,much less than the contributions of soil and plant variables,suggest that warming has a direct effect on the variation of microbial community,and soil and plant properties are more important in shaping microbial communities via indirect warming effects in this alpine meadow ecosystem.Taken together,we concluded that bacterial communities rapidly respond to short-term warming on Tibetan Plateau,and the changes in specific bacterial phyla may have the potential to modify ecosystem function.更多还原