生态学报Issue(19)：6530-6540,11.DOI:10.5846/stxb201403220513
温带针阔混交林土壤碳氮气体通量的主控因子与耦合关系
The controlling factors and coupling of soil CO2, CH4 and N2O fluxes in a temperate needle-broadleaved mixed forest
摘要
Abstract
Carbon dioxide ( CO2 ) , methane ( CH4 ) and nitrous oxide ( N2 O) are three major greenhouse gases, accounting for 80% of global warming. Forest ecosystems comprise the largest carbon stocks in terrestrial ecosystems, and function as important sinks and sources of atmospheric CO2 , CH4 and N2 O. Complicated interactions occur during the generation and absorption of soil CO2 , CH4 and N2 O, including synergies, tradeoffs, and randomness. High-latitude forests are experiencing the effects of significant global change ( e. g., warming, changed precipitation, and increased nitrogen deposition) , leading to great uncertainty in estimates of soil greenhouse gas fluxes. Furthermore, the factors controlling the coupling of soil CO2 , CH4 and N2 O fluxes remain unclear. This study was conducted in the temperate needle-broadleaved mixed forest of Changbai Mountain, Northeast China. The net exchange fluxes of soil CO2 , CH4 and N2 O, as well as soil temperature and soil moisture, were measured over four years (2005–2009) using static chamber and gas chromatograph techniques. The results showed that temperate needle-broadleaved mixed forest soils behaved as a source of atmospheric CO2 and N2 O but a sink of atmospheric CH4 over the course of the study. The average soil CH4 , CO2 and N2 O fluxes were estimated at -1.30 kg CH4 hm-2 a-1 , 15102.2 kg CO2 hm-2 a-1 , and 6.13 kg N2 O hm-2 a-1 , respectively. In addition, soil CO2 flux exhibited significant seasonality, and was mainly affected by soil temperature, followed by soil moisture. Seasonal variation in soil CH4 flux was less significant than that of soil CO2 and N2 O fluxes; moreover, it was positively correlated with soil moisture. When soil temperatures were within a threshold range, soil moisture determined CH4 production and oxidation in soil profiles by regulating CH4 and O2 diffusion as well as methanotrophic community activity. Similar to soil CO2 flux, soil N2 O flux was significantly correlated with soil moisture and soil temperature. Furthermore, there were no significant relationships between soil CO2 flux and soil CH4 flux, or between soil CO2 flux and soil N2 O flux, which exhibited a random relationship. However, a significant negative relationship between soil CH4 uptake and N2 O emission was found, indicating a tradeoff between them. The random relationship between soil CO2 and CH4 fluxes was attributed to their different pathways and substrate utilization. The trade-off relationship between soil CH4 and N2 O fluxes was related to moisture control and competition for mono-oxygenase ( MMO) between ammonia-oxidizers and methanotrophic communities. The weak synergy between soil CO2 and N2 O fluxes reflected that they were driven by same environmental factors, such as soil temperature and moisture, and that no microbial mechanisms drove their production or consumption. <br> These results suggest that soil carbon and nitrogen gas fluxes are mainly driven by environmental factors and substrate availability, and their complicated couplings are related to the activity and functional composition of microbial communities. It is necessary to further explore the effects of environmental change on the coupling of soil CO2 , CH4 and N2 O fluxes as well as the microbial mechanisms underlying these using molecular biology and metagenomic analyses.关键词
土壤CO2通量/土壤CH4通量/土壤N2 O通量/主控因子/耦合关系Key words
soil CO2 flux/soil CH4 flux/soil N2 O flux/controlling factors/coupling引用本文复制引用
党旭升,李林森,王磊,程淑兰,方华军,于贵瑞,韩士杰,张军辉,王淼,王永生,徐敏杰..温带针阔混交林土壤碳氮气体通量的主控因子与耦合关系[J].生态学报,2015,(19):6530-6540,11.基金项目
国家自然科学基金(31290221,41471212,31470558,31290222,31130009) （31290221,41471212,31470558,31290222,31130009）
国家重点基础研究发展计划项目(2012CB417103) （2012CB417103）
中国科学院地理科学与资源研究所“秉维”优秀青年人才基金(2011RC202) （2011RC202）
中国科学院战略性先导科技专项(XDA05050600) （XDA05050600）
