title: Modelling terrestrial nitrous oxide emissions and implications for climate feedback.
abstract: Ecosystem nitrous oxide (N2O) emissions respond to changes in climate and CO2 concentration as well as anthropogenic nitrogen (N) enhancements. Here, we aimed to quantify the responses of natural ecosystem N2O emissions to multiple environmental drivers using a process-based global vegetation model (DyN-LPJ). We checked that modelled annual N2O emissions from nonagricultural ecosystems could reproduce field measurements worldwide, and experimentally observed responses to step changes in environmental factors. We then simulated global N2O emissions throughout the 20th century and analysed the effects of environmental changes. The model reproduced well the global pattern of N2O emissions and the observed responses of N cycle components to changes in environmental factors. Simulated 20th century global decadal-average soil emissions were c. 8.2-9.5 Tg N yr(-1) (or 8.3-10.3 Tg N yr(-1) with N deposition). Warming and N deposition contributed 0.85±0.41 and 0.80±0.14 Tg N yr(-1), respectively, to an overall upward trend. Rising CO2 also contributed, in part, through a positive interaction with warming. The modelled temperature dependence of N2O emission (c. 1 Tg N yr(-1) K(-1)) implies a positive climate feedback which, over the lifetime of N2O (114 yr), could become as important as the climate-carbon cycle feedback caused by soil CO2 release.
authors.affiliation: Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.
authors.lastname: Xu-Ri
authors.affiliation: Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia.|Division of Ecology and Evolution, Grantham Institute for Climate Change, Imperial College, Silwood Park, Ascot, SL5 7PY, UK.
authors.forename: I Colin
authors.initials: IC
authors.lastname: Prentice
authors.affiliation: Climate and Environmental Physics, Physics Institute and Oeschger Centre for Climate Change Research, University of Bern, Sidlerstrasse 5, CH-3012, Bern, Switzerland.
authors.forename: Renato
authors.initials: R
authors.lastname: Spahni
authors.affiliation: Graduate University of the Chinese Academy of Sciences, College of Resources and Environment, Beijing, 100049, China.
authors.forename: Hai Shan
authors.initials: HS
authors.lastname: Niu
mesh_terms: D000383:Agriculture; D002245:Carbon Dioxide / Q000494:pharmacology; D002980:Climate; D003198:Computer Simulation; D005246:Feedback; D005843:Geography; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism; D009609:Nitrous Oxide / Q000032:analysis*; D011891:Rain; D012044:Regression Analysis; D012987:Soil / Q000737:chemistry; D013696:Temperature
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D009609:Nitrous Oxide; D009584:Nitrogen