Vegetation functional properties determine uncertainty of simulated ecosystem productivity in the East Asian monsoon region

Cui, Erqian; Cui, Erqian; Cui, Erqian

Tuesday, August 13, 2019

Exhibit Hall, Kentucky International Convention Center

Erqian Cui¹, Kun Huang¹, Altaf M. Arain², Joshua B. Fisher³, Deborah Huntzinger⁴, Akihiko Ito⁵, Yiqi Luo⁶, Atul Jain⁷, Jiafu Mao⁸, Anna M. Michalak⁹, Shuli Niu¹⁰, Nicholas. C. Parazoo¹¹, Changhui Peng¹², Shushi Peng¹³, Benjamin Poulter¹⁴, Dan M. Ricciuto⁸, Kevin Schaefer¹⁵, Christopher Schwalm⁴, Xiaoying Shi⁸, Hanqin Tian¹⁶, Weile Wang¹⁷, Jinsong Wang¹⁸, Yaxing Wei¹⁹, Enrong Yan¹, Liming Yan¹, Ning Zeng²⁰, Qiuan Zhu²¹ and Jianyang Xia¹, (1)School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China, (2)School of geography and earth science, Mcmaster University, Hamilton, ON, Canada, (3)NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, (4)School of Earth Sciences & Environmental Sustainability, Northern Arizona University, Flagstaff, AZ, (5)Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Japan, (6)Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, (7)Department of Atmospheric Sciences, University of Illinois, Urbana, IL, (8)Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, (9)Department of Global Ecology, Carnegie Institution for Science, Stanford, CA, (10)Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China, (11)Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, (12)Institute of Environment Sciences, University of Quebec at Montreal, Montreal, QC, Canada, (13)Peking University, Beijing, China, (14)Biospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, (15)University of Colorado - Boulder, National Snow & Ice Data Center, Boulder, CO, (16)International Center for Climate and Global Change Research and School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, (17)NASA ARC-CREST, Moffett Field, CA, (18)University of Chinese Academy of Sciences, Beijing, China, (19)Environmental Sciences Division & Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, (20)UMD, College Park, (21)College of Forestry,Northwest A&F University, Yangling, China

Background/Question/Methods

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 the highest productivity, but its estimate by current generation of terrestrial biosphere models (TBMs) has seldom been systematically evaluated or benchmarked. Here, we examine 15 TBMs participating in the Multi-scale Synthesis and Terrestrial Model Inter-comparison Project (MsTMIP) for their ability to estimate GPP in the East Asian Monsoon region during 1901-2010. The model evaluation in our study is based on a traceability framework, which links GPP to net primary productivity (NPP), biomass, and leaf area via incorporating multiple vegetation functional properties, including carbon-use efficiency (CUE), vegetation C turnover time (τ_veg), leaf C fraction (F_leaf), specific leaf area (SLA), and LAI-level photosynthesis (P_LAI). First, the effects of initial conditions and environmental changes on inter-model variations in GPP are separately evaluated. Then, modeled GPP is further decomposed into the subsequent C-accumulation processes and associated vegetation functional properties. Their relative contributions in controlling model performance on GPP are also quantified. Second, the key uncertainty processes and vegetation functional properties are evaluated by comparing with available observations and remote-sensing data products.

Results/Conclusions

The results showed that the large inter-model variation of GPP (1280±422 g C m^-2 yr^-1) over 1901-2010 was mainly propagated from their different representation of vegetation functional properties. For example, SLA explained 77% of the inter-model difference in leaf area, which contributed 90% to the simulated GPP differences under initial conditions without environmental changes. In comparison with observed vegetation functional properties, the models simulated a higher CUE (18.1±21.3%), τ_veg (18.2±26.9%) and SLA (27.4±36.5%), leading to the overestimate 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. Overall, this study highlights that the modeling of ecosystem productivity at mid-to-low latitudes could benefit from a better understanding of the co-variations between plant functional properties and canopy C processes in terrestrial ecosystems.

PS 22-53 - Vegetation functional properties determine uncertainty of simulated ecosystem productivity in the East Asian monsoon region