Biotic and climatic controls on interannual variability in carbon fluxes across terrestrial ecosystems

Authors

Junjiong Shao, Fudan University
Xuhui Zhou, Fudan 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, BoulderFollow
Rosvel Bracho, University of Florida
Jiquan Chen, University of ToledoFollow
Marc L. 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 E. 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

2015

Citation

Agricultural and Forest Meteorology 205 (2015) 11–22, http://dx.doi.org/10.1016/j.agrformet.2015.02.007 0168-1923.

Comments

U. S. government work.

Abstract

Interannual variability (IAV, represented by standard deviation) in net ecosystem exchange of CO₂ (NEE) is mainly driven by climatic drivers and biotic variations (i.e., the changes in photosynthetic and respiratory responses to climate), the effects of which are referred to as climatic (CE) and biotic effects (BE), respectively. Evaluating the relative contributions of CE and BE to the IAV in carbon (C) fluxes and understanding their controlling mechanisms are critical in projecting ecosystem changes in the future climate. In this study, we applied statistical methods with flux data from 65 sites located in the Northern Hemisphere to address this issue. Our results showed that the relative contribution of BE (CnBE) and CE (CnCE) to the IAV in NEE was 57%±14% and 43%±14%, respectively. The discrepancy in the CnBE among sites could be largely explained by water balance index (WBI). Across water-stressed ecosystems, the CnBE decreased with increasing aridity (slope = 0.18%mm⁻¹). In addition, the CnBE tended to increase and the uncertainty reduced as time span of available data increased from 5 to 15 years. Inter-site variation of the IAV in NEE mainly resulted from the IAV in BE (72%) compared to that in CE (37%). Interestingly, positive correlations between BE and CE occurred in grasslands and dry ecosystems (r > 0.45, P < 0.05) but not in other ecosystems. These results highlighted the importance of BE in determining the IAV in NEE and the ability of ecosystems to regulate C fluxes under climate change might decline when the ecosystems experience more severe water stress in the future.