Articles | Volume 8, issue 6
Biogeosciences, 8, 1667–1678, 2011
Biogeosciences, 8, 1667–1678, 2011

Research article 23 Jun 2011

Research article | 23 Jun 2011

Underestimated effects of low temperature during early growing season on carbon sequestration of a subtropical coniferous plantation

W.-J. Zhang1,2, H.-M. Wang1, F.-T. Yang1, Y.-H. Yi3, X.-F. Wen1, X.-M. Sun1, G.-R. Yu1, Y.-D. Wang4, and J.-C. Ning5 W.-J. Zhang et al.
  • 1Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
  • 2State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China
  • 3Numerical Terradynamic Simulation Group, University of Montana, Missoula, MT, USA
  • 4Key Laboratory for Water Environment and Resources, Tianjin Normal University, Tianjin 300387, China
  • 5Shandong Economic University, Jinan 250014, China

Abstract. The impact of air temperature in early growing season on the carbon sequestration of a subtropical coniferous plantation was discussed through analyzing the eddy flux observations at Qianyanzhou (QYZ) site in southern China from 2003 to 2008. This site experienced two cold early growing seasons (with temperature anomalies of 2–5 °C) in 2005 and 2008, and a severe summer drought in 2003.
Results indicated that the low air temperature from January to March was the major factor controlling the inter-annual variations in net carbon uptake at this site, rather than the previously thought summer drought. The accumulative air temperature from January to February showed high correlation (R2=0.970, p<0.001) with the annual net ecosystem production (NEP). This was due to the controls of early-month temperature on the plant phenology developing and the growing season length at this subtropical site. The cold spring greatly shortened the growing season length and therefore reduced the carbon uptake period. The eddy flux observations showed a carbon loss of 4.04 g C m−2 per growing-season day at this coniferous forest site. On the other hand, the summer drought also reduced the net carbon uptake strength because the photosynthesis was more sensitive to water deficit stress than the ecosystem respiration. However, the impact of summer drought occurred within a relatively shorter period and the carbon sequestration went back to the normal level once the drought was relieved.

Final-revised paper