生态学报2018，Vol.38Issue(7)：2279-2287,9.DOI:10.5846/stxb201705100859
氮添加对高寒草甸土壤微生物呼吸及其温度敏感性的影响
Effects of nitrogen additions on soil microbial respiration and its temperature sensitivity in a Tibetan alpine meadow
摘要
Abstract
The soil C stock of the Tibetan Plateau is of global significance because of its large pool size and the potential positive feedback to climate wanning.Soil microbial respiration is an important carbon (C) flux of the global C cycle,and is greatly affected by soil nitrogen (N) availability.Reactive N inputs often reduce soil microbial respiration,but how they affect the temperature sensitivity of soil microbial respiration is still poorly understood.Here,we examined the effect of N additions on soil microbial respiration and its temperature sensitivity (expressed as Q10),and assessed the relative importance of substrate availability and the chemical composition of soil organic C in explaining the variation in soil microbial respiration and Q10.A 4-year field experiment with four simulated N deposition levels,0,5,10,and 15g N m-2 a-1 was conducted.Soil samples were collected from three levels of nitrogen addition rate (0,5,and 15g N m-2 a-1) and incubated at 5℃,15℃ and 25℃ in the laboratory.The results showed that N additions significantly increased soil dissolved organic C and available N (P＜0.05),but did not significantly affect soil pH,soil organic C,total N,available P,and total P.Moreover,N additions did not affect microbial biomass C,but significantly decreased microbial biomass N (P＜0.05).The solid-state 13C nuclear magnetic resonance showed that N additions decreased the relative content of O-alkyl C,but increased the relative contents of alkyl C,aromatic C,and carboxylic C,which resulted in higher aromaticity and aliphaticity of soil organic carbon under N addition treatments than that of the control treatment.We also found that N additions significantly decreased soil microbial respiration rate and cumulative C efflux under three temperatures (P＜0.05),but significantly increased Q10 under the incubation temperature of 15℃ and 25℃ (P＜0.05).Linear correlation analysis showed that microbial respiration was negatively correlated with the complexity of soil organic C,whereas Q1o under the incubation temperature of 15℃ and 25℃ was positively correlated with the complexity of soil organic C.These findings support the prediction based on kinetic theory that soil organic C,with recalcitrant molecular structure,has a high temperature sensitivity of respiration.Together,our results suggest that changes in chemical structure of soil organic C induced by N inputs may play an important role in regulating the response of soil microbial respiration to elevated temperature,and further increase the uncertainty in predicting net soil C losses in the scenario of warming on the Tibetan Plateau.关键词
高寒草甸/氮添加/土壤微生物呼吸/温度敏感性Key words
alpine meadow/nitrogen addition/soil microbial respiration/temperature sensitivity引用本文复制引用
叶成龙,张浩,周小龙,周显辉,郭辉,胡水金..氮添加对高寒草甸土壤微生物呼吸及其温度敏感性的影响[J].生态学报,2018,38(7):2279-2287,9.基金项目
南京农业大学中央高校基本业务费(0306J0887,KYTZ201404) （0306J0887,KYTZ201404）
