Direct and indirect effects of climatic variations on the interannual variability in net ecosystem exchange across terrestrial ecosystems

Authors

Junjiong Shao, East China Normal University
Xuhui Zhou, East China Normal UniversityFollow
Yiqi Luo, University of Oklahoma
Bo Li, Fudan University
Mika Aurela, Finnish Meteorological Institute
David Billesbach, University of Nebraska–LincolnFollow
Peter D. Blanken, University of Colorado at Boulder
Rosvel Bracho, University of Florida
Jiquan Chen, Michigan State University
Marc Fischer, University of Nebraska - LincolnFollow
Yuling Fu, East China Normal University
Lianhong Gu, Oak Ridge National Laboratory
Shijie Han, Chinese Academy of Sciences
Yongtao He, Chinese Academy of Sciences
Thomas Kolb, Northern Arizona University
Yingnian Li, Chinese Academy of Sciences
Zoltan Nagy, Szent Istvan University
Shuli Niu, Chinese Academy of Sciences
Walter C. Oechel, San Diego State University
Krisztina Pinter, Szent Istvan University
Peili Shi, Chinese Academy of Sciences
Andrew Suyker, University of Nebraska - LincolnFollow
Margaret Torn, University of Nebraska - Lincoln
Andrej Varlagin, Russian Academy of Sciences
Huimin Wang, Chinese Academy of Sciences
Junhua Yan, Chinese Academy of Sciences
Guirui Yu, Chinese Academy of Sciences
Junhui Zhang, Chinese Academy of Sciences

Date of this Version

2016

Citation

Tellus B 2016, 68, 30575

Comments

© 2016 J. Shao et al.

Open access

http://dx.doi.org/10.3402/tellusb.v68.30575

Abstract

Climatic variables not only directly affect the interannual variability (IAV) in net ecosystem exchange of CO2 (NEE) but also indirectly drive it by changing the physiological parameters. Identifying these direct and indirect paths can reveal the underlying mechanisms of carbon (C) dynamics. In this study, we applied a path analysis using flux data from 65 sites to quantify the direct and indirect climatic effects on IAV in NEE and to evaluate the potential relationships among the climatic variables and physiological parameters that represent physiology and phenology of ecosystems. We found that the maximum photosynthetic rate was the most important factor for the IAV in gross primary productivity (GPP), which was mainly induced by the variation in vapour pressure deficit. For ecosystem respiration (RE), the most important drivers were GPP and the reference respiratory rate. The biome type regulated the direct and indirect paths, with distinctive differences between forests and non-forests, evergreen needleleaf forests and deciduous broadleaf forests, and between grasslands and croplands. Different paths were also found among wet, moist and dry ecosystems. However, the climatic variables can only partly explain the IAV in physiological parameters, suggesting that the latter may also result from other biotic and disturbance factors. In addition, the climatic variables related to NEE were not necessarily the same as those related to GPP and RE, indicating the emerging difficulty encountered when studying the IAV in NEE. Overall, our results highlight the contribution of certain physiological parameters to the IAV in C fluxes and the importance of biome type and multi-year water conditions, which should receive more attention in future experimental and modelling research.