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Maximum Carbon Uptake Rate Dominates the Interannual Variability of Global Net Ecosystem ExchangeTerrestrial ecosystems contribute most of the interannual variability (IAV) in atmospheric carbon dioxide (CO2) concentrations, but processes driving the IAV of net ecosystem CO2 exchange (NEE) remain elusive. For a predictive understanding of the global C cycle, it is imperative to identify indicators associated with ecological processes that determine the IAV of NEE. Here, we decompose the annual NEE of global terrestrial ecosystems into their phenological and physiological components, namely maximum carbon uptake (MCU) and release (MCR), the carbon uptake period (CUP), and two parameters, α and β, that describe the ratio between actual versus hypothetical maximum C sink and source, respectively. Using long‐term observed NEE from 66 eddy covariance sites and global products derived from FLUXNET observations, we found that the IAV of NEE is determined predominately by MCU at the global scale, which explains 48% of the IAV of NEE on average while α, CUP, β, and MCR explain 14%, 25%, 2%, and 8%, respectively. These patterns differ in water‐limited ecosystems versus temperature‐ and radiation‐limited ecosystems; 31% of the IAV of NEE is determined by the IAV of CUP in water‐limited ecosystems, and 60% of the IAV of NEE is determined by the IAV of MCU in temperature‐ and radiation‐limited ecosystems. The Lund‐Potsdam‐Jena (LPJ) model and the Multi‐scale Synthesis and Terrestrial Model Inter‐comparison Project (MsTMIP) models underestimate the contribution of MCU to the IAV of NEE by about 18% on average, and overestimate the contribution of CUP by about 25%. This study provides a new perspective on the proximate causes of the IAV of NEE, which suggest that capturing the variability of MCU is critical for modeling the IAV of NEE across most of the global land surface.

Document ID
20190032412
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Fu, Zheng (Chinese Academy of Sciences Beijing, China)
Stoy, Paul C. (Montana State Univ. Bozeman, MT, United States)
Poulter, Benjamin (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Gerken, Tobias (Pennsylvania State Univ. University Park, PA, United States)
Zhang, Zhen (Maryland Univ. College Park, MD, United States)
Wakbulcho, Guta (Montana State Univ. Bozeman, MT, United States)
Niu, Shuli (Chinese Academy of Sciences Beijing, China)
Date Acquired
October 30, 2019
Publication Date
June 14, 2019
Publication Information
Publication: Global Change Biology
Volume: 25
Issue: 10
ISSN: 1354-1013
Subject Category
Life Sciences (General)
Report/Patent Number
GSFC-E-DAA-TN73315
Funding Number(s)
CONTRACT_GRANT: 2018YFA0606102
CONTRACT_GRANT: EF 1702029
CONTRACT_GRANT: GBMF5439;
CONTRACT_GRANT: 131A11KYSB20180010
CONTRACT_GRANT: OIA 1632810
CONTRACT_GRANT: DEB 1552976
CONTRACT_GRANT: USDA‐NIFA 228396
CONTRACT_GRANT: 31625006
Distribution Limits
Public
Copyright
Use by or on behalf of the US Gov. Permitted.

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