title: Molecular mechanisms of water table lowering and nitrogen deposition in affecting greenhouse gas emissions from a Tibetan alpine wetland.
abstract: Rapid climate change and intensified human activities have resulted in water table lowering (WTL) and enhanced nitrogen (N) deposition in Tibetan alpine wetlands. These changes may alter the magnitude and direction of greenhouse gas (GHG) emissions, affecting the climate impact of these fragile ecosystems. We conducted a mesocosm experiment combined with a metagenomics approach (GeoChip 5.0) to elucidate the effects of WTL (-20 cm relative to control) and N deposition (30 kg N ha-1yr-1) on carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes as well as the underlying mechanisms. Our results showed that WTL reduced CH4emissions by 57.4% averaged over three growing seasons compared with no-WTL plots, but had no significant effect on net CO2uptake or N2O flux. N deposition increased net CO2uptake by 25.2% in comparison with no-N deposition plots and turned the mesocosms from N2O sinks to N2O sources, but had little influence on CH4emissions. The interactions between WTL and N deposition were not detected in all GHG emissions. As a result, WTL and N deposition both reduced the global warming potential (GWP) of growing season GHG budgets on a 100-year time horizon, but via different mechanisms. WTL reduced GWP from 337.3 to -480.1 g CO2-eq m-2mostly because of decreased CH4emissions, while N deposition reduced GWP from 21.0 to -163.8 g CO2-eq m-2, mainly owing to increased net CO2uptake. GeoChip analysis revealed that decreased CH4production potential, rather than increased CH4oxidation potential, may lead to the reduction in net CH4emissions, and decreased nitrification potential and increased denitrification potential affected N2O fluxes under WTL conditions. Our study highlights the importance of microbial mechanisms in regulating ecosystem-scale GHG responses to environmental changes.
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, 5 Yiheyuan Road, Beijing, 100871, China.|Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xining Road, Xining, 810008, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Beijing, 100093, China.
authors.forename: Lingfei
authors.initials: L
authors.lastname: Yu
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xining Road, Xining, 810008, China.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xining Road, Xining, 810008, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xining Road, Xining, 810008, China.
authors.forename: Litong
authors.initials: L
authors.lastname: Chen
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xining Road, Xining, 810008, China.
authors.forename: Guangmin
authors.initials: G
authors.lastname: Cao
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, 1 Tsinghua Garden Road, Beijing, 100084, China.
authors.forename: Haowei
authors.initials: H
authors.lastname: Yue
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, 1 Tsinghua Garden Road, Beijing, 100084, China.|Department of Microbiology and Plant Biology, Institute for Environmental Genomics, University of Oklahoma, Norman, OK, 73019, USA.|Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, 1 Tsinghua Garden Road, Beijing, 100084, China.
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, 5 Yiheyuan Road, Beijing, 100871, China.
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, 5 Yiheyuan Road, Beijing, 100871, China.|Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xining Road, Xining, 810008, China.
authors.forename: Jin-Sheng
authors.initials: JS
authors.lastname: He
mesh_terms: D001419:Bacteria / Q000235:genetics; D002245:Carbon Dioxide; D057231:Climate Change; D017752:Greenhouse Effect; D060587:Groundwater; D008697:Methane; D009584:Nitrogen; D009609:Nitrous Oxide; D018609:Tibet; D053833:Wetlands
chemical_list: D002245:Carbon Dioxide; D009609:Nitrous Oxide; D009584:Nitrogen; D008697:Methane
keywords: carbon cycle; climate warming; methane; microbial functional gene; nitrous oxide; the Tibetan Plateau