Abstract
Global and regional projections of climate change by Earth system models are limited by their uncertain estimates of terrestrial ecosystem productivity. At the middle to low latitudes, the East Asian monsoon region has higher productivity than forests in Europe-Africa and North America, but its estimate by current generation of terrestrial biosphere models (TBMs) has seldom been systematically evaluated. Here, we developed a traceability framework to evaluate the simulated gross primary productivity (GPP) by 15 TBMs in the East Asian monsoon region. The framework links GPP to net primary productivity, biomass, leaf area and back to GPP via incorporating multiple vegetation functional properties of carbon-use efficiency (CUE), vegetation C turnover time (τveg), leaf C fraction (Fleaf), specific leaf area (SLA), and leaf area index (LAI)-level photosynthesis (PLAI), respectively. We then applied a relative importance algorithm to attribute intermodel variation at each node. The results showed that large intermodel variation in GPP over 1901–2010 were mainly propagated from their different representation of vegetation functional properties. For example, SLA explained 77% of the intermodel difference in leaf area, which contributed 90% to the simulated GPP differences. In addition, the models simulated higher CUE (18.1 ± 21.3%), τveg (18.2 ± 26.9%), and SLA (27.4±36.5%) than observations, leading to the overestimation of simulated GPP across the East Asian monsoon region. These results suggest the large uncertainty of current TBMs in simulating GPP is largely propagated from their poor representation of the vegetation functional properties and call for a better understanding of the covariations between plant functional properties in terrestrial ecosystems.
| Original language | English |
|---|---|
| Pages (from-to) | 668-689 |
| Number of pages | 22 |
| Journal | Global Biogeochemical Cycles |
| Volume | 33 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 2019 |
Funding
This work was financially supported by the National Key R&D Program of China (2017YFA0604603), National Natural Science Foundation of China (31722009, 41630528), the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China (Grant 161016), and National 1000 Young Talents Program of China. Funding for the Multiscale synthesis and Terrestrial Model Intercomparison Project (MsTMIP; https://nacp.ornl.gov/MsTMIP.shtml) activity was provided through NASA ROSES Grant NNX10AG01A. Data management support for preparing, documenting, and distributing model driver and output data was performed by the Modeling and Synthesis Thematic Data Center at Oak Ridge National Laboratory (ORNL; http://nacp.ornl.gov), with funding through NASA ROSES Grant NNH10AN681. Finalized MsTMIP data products are archived at the ORNL DAAC (http://daac.ornl.gov). We also acknowledge the modeling groups that provided results to MsTMIP and their funding sources. This work was financially supported by the National Key R&D Program of China (2017YFA0604603), National Natural Science Foundation of China (31722009, 41630528), the Fok Ying‐ Tong Education Foundation for Young Teachers in the Higher Education Institutions of China (Grant 161016), and National 1000 Young Talents Program of China. Funding for the Multiscale synthesis and Terrestrial Model Intercomparison Project (MsTMIP; https://nacp.ornl.gov/ MsTMIP.shtml) activity was provided through NASA ROSES Grant NNX10AG01A. Data management sup port for preparing, documenting, and distributing model driver and output data was performed by the Modeling and Synthesis Thematic Data Center at Oak Ridge National Laboratory (ORNL; http://nacp.ornl.gov), with funding through NASA ROSES Grant NNH10AN681. Finalized MsTMIP data products are archived at the ORNL DAAC (http://daac.ornl.gov). We also acknowledge the modeling groups that provided results to MsTMIP and their funding sources. J. B. F. contributed to this work from the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. California Institute of Technology, Government sponsorship acknowledged. TRIPLEX‐GHG: TRIPLEX‐GHG was developed at University of Quebec at Montreal (Canada) and Northwest A&F University (China) and has been supported by the National Basic Research Program of China (2013CB956602) and the National Science and Engineering Research Council of Canada (NSERC) Discover Grant. C. L. M: This research is supported in part by the US Department of Energy (DOE), Office of Science, Biological and Environmental Research. Oak Ridge National Laboratory is managed by UT‐Battelle, LLC for DOE under contract DE‐AC05‐ 00OR22725. The authors declare that the data supporting the finding of this study are available within the article and its supporting information files. Model results are available from the MsTMIP Global Simulation Results version 1.0. The URL for the data is https://doi.org/10.3334/ORNLDAAC/ 1225. The MODIS GPP/NPP data were provided by the Numerical Terradynamic Simulation Group (NTSG) at the University of Montana (ftp://ftp.ntsg.umt.edu/pub/MODIS/ NTSG_Products/https://lpdaac.usgs. gov/dataset_discove‐ry/modis/modis_ products_table/mod17a3). MTE GPP estimates used in this study are avail able from Jung et al., 2011; https://doi.
Keywords
- MsTMIP
- environmental drivers
- initial conditions
- model uncertainty
- relative importance
- vegetation functional property