Responses of soil microbial communities and functions associated with organic carbon mineralization to nitrogen addition in a Tibetan grassland  

作　　者：Ruyi LUO Jiafa LUO Jianling FAN Deyan LIU Jin-Sheng HE Nazia PERVEEN Weixin DING 

机构地区：[1]State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China [2]University of Chinese Academy of Sciences,Beijing 10049,China [3]AgResearch Limited,Ruakura Research Centre,Hamilton 3240,New Zealand [4]Department of Ecology,College of Urban and Environmental Sciences,Key Laboratory for Earth Surface Processes of the Ministry of Education,Peking University,Beijing 100871,China

出　　处：《Pedosphere》2020年第2期214-225,共12页土壤圈（英文版）

基　　金：supported by the National Program on Key Basic Research Project(No.2014CB954002);the National Natural Science Foundation of China(No.31561143011)。

摘　　要：Alpine grasslands with a high soil organic carbon(SOC)storage on the Tibetan Plateau are experiencing rapid climate warming and anthropogenic nitrogen(N)deposition;this is expected to substantially increase the soil N availability,which may impact carbon(C)cycling.However,little is known regarding how N enrichment influences soil microbial communities and functions relative to C cycling in this region.We conducted a 4-year field experiment on an alpine grassland to evaluate the effects of four different rates of N addition(0,25,50,and 100 kg N ha^-1 year^-1)on the abundance and community structure(phospholipid fatty acids,PLFAs)of microbes,enzyme activities,and community level physiological profiles(CLPP)in soil.We found that N addition increased the microbial biomass C(MBC)and N(MBN),along with an increased abundance of bacterial PLFAs,especially Gram-negative bacterial PLFAs,with a decreasing ratio of Gram-positive to Gram-negative bacteria.The N addition also stimulated the growth of fungi,especially arbuscular mycorrhizal fungi,reducing the ratio of fungi to bacteria.Microbial functional diversity and activity of enzymes involved in C cycling(β-1,4-glucosidase and phenol oxidase)and N cycling(β-1,4-N-acetyl-glucosaminidase and leucine aminopeptidase)increased after N addition,resulting in a loss of SOC.A meta-analysis showed that the soil C/N ratio was a key factor in the response of oxidase activity to N amendment,suggesting that the responses of soil microbial functions,which are linked to C turnover relative to N input,primarily depended upon the soil C/N ratio.Overall,our findings highlight that N addition has a positive influence on microbial communities and their associated functions,which may reduce soil C storage in alpine grasslands under global change scenarios.

关 键 词：ALPINE GRASSLAND C cycling C TURNOVER COMMUNITY level physiological profiles(CLPP) enzyme activity MICROBIAL COMMUNITY composition MICROBIAL function N input 

分 类 号：S812.2[农业科学—草业科学]