title: Evaluating carbon fluxes of global forest ecosystems by using an individual tree-based model FORCCHN.
abstract: The carbon budget of forest ecosystems, an important component of the terrestrial carbon cycle, needs to be accurately quantified and predicted by ecological models. As a preamble to apply the model to estimate global carbon uptake by forest ecosystems, we used the CO2flux measurements from 37 forest eddy-covariance sites to examine the individual tree-based FORCCHN model's performance globally. In these initial tests, the FORCCHN model simulated gross primary production (GPP), ecosystem respiration (ER) and net ecosystem production (NEP) with correlations of 0.72, 0.70 and 0.53, respectively, across all forest biomes. The model underestimated GPP and slightly overestimated ER across most of the eddy-covariance sites. An underestimation of NEP arose primarily from the lower GPP estimates. Model performance was better in capturing both the temporal changes and magnitude of carbon fluxes in deciduous broadleaf forest than in evergreen broadleaf forest, and it performed less well for sites in Mediterranean climate. We then applied the model to estimate the carbon fluxes of forest ecosystems on global scale over 1982-2011. This application of FORCCHN gave a total GPP of 59.41±5.67 and an ER of 57.21±5.32PgCyr-1for global forest ecosystems during 1982-2011. The forest ecosystems over this same period contributed a large carbon storage, with total NEP being 2.20±0.64PgCyr-1. These values are comparable to and reinforce estimates reported in other studies. This analysis highlights individual tree-based model FORCCHN could be used to evaluate carbon fluxes of forest ecosystems on global scale.
authors.affiliation: MOA Key Laboratory of Crop Eco-physiology and Farming System in the Middle Reaches of the Yangtze River/College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.
authors.forename: Jianyong
authors.initials: J
authors.lastname: Ma
authors.affiliation: Department of Environmental Sciences, University of Virginia, Charlottesville, VA 22904, USA.
authors.forename: Herman H
authors.initials: HH
authors.lastname: Shugart
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China. Electronic address: yxd@bnu.edu.cn.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Yan
authors.affiliation: MOA Key Laboratory of Crop Eco-physiology and Farming System in the Middle Reaches of the Yangtze River/College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Cougui
authors.initials: C
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Fang
mesh_terms: D002244:Carbon; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000032:analysis*; D002980:Climate; D065928:Forests; D008962:Models, Theoretical; D014197:Trees
chemical_list: D002245:Carbon Dioxide; D002244:Carbon
keywords: Ecosystem respiration; Eddy-covariance; Forest ecosystems; Gross primary production; Individual tree-based model FORCCHN; Net ecosystem production