title: Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China.
abstract: We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning.
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, P.R. China.
authors.forename: Hongxin
authors.initials: H
authors.lastname: Su
authors.affiliation: College of Life and Environmental Science, Minzu University of China, 100081 Beijing, P.R. China.
authors.forename: Jinchao
authors.initials: J
authors.lastname: Feng
authors.affiliation: UCL Department of Geography, University College London, Pearson Building, Gower Street, London WC1E 6BT, UK.
authors.forename: Jan C
authors.initials: JC
authors.lastname: Axmacher
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, P.R. China.
authors.forename: Weiguo
authors.initials: W
authors.lastname: Sang
mesh_terms: D002244:Carbon; D002681:China; D002980:Climate; D017753:Ecosystem; D065928:Forests; D065948:Grassland; D008962:Models, Theoretical
chemical_list: D002244:Carbon