Evolution and variation of atmospheric carbon dioxide concentration over terrestrial ecosystems as derived from eddy covariance measurements

Published Date

August 2015, Vol.114:75–82, doi:10.1016/j.atmosenv.2015.05.026

Title 

Evolution and variation of atmospheric carbon dioxide concentration over terrestrial ecosystems as derived from eddy covariance measurements

• Author 

• Min Liu ^a,,
• Jiabing Wu ^b
• Xudong Zhu ^c,d
• Honglin He ^e
• Wenxiao Jia ^a
• Weining Xiang ^a

• aShanghai Key Laboratory for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China
• bState Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
• cNatural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, USA
• dEarth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
• eKey Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources, Chinese Academy of Sciences, Beijing 100101, China

Received 22 August 2014. Revised 26 April 2015. Accepted 14 May 2015. Available online 15 May 2015.

Highlights

• •
  Atmospheric CO₂ concentration over terrestrial ecosystems (ACTE) was analyzed.
• •
  ACTE was higher by 9.0 ppm in winter and lower 2.1 ppm in summer than global means.
• •
  Annual mean and seasonal amplitude of ACTE increased with 2.04 and 0.60 ppm yr⁻¹.
• •
  The annual CO₂ concentration showed large variation among ecosystems.

Abstract

Carbon dioxide (CO₂) is the most important anthropogenic greenhouse gas contributing to global climate change. Understanding the temporal and spatial variations of CO₂ concentration over terrestrial ecosystems provides additional insight into global atmospheric variability of CO₂ concentration. Using 355 site-years of CO₂concentration observations at 104 eddy-covariance flux tower sites in Northern Hemisphere, we presented a comprehensive analysis of evolution and variation of atmospheric CO₂ concentration over terrestrial ecosystem (ACTE) for the period of 1997–2006. Our results showed that ACTE exhibited a strong seasonal variations, with an average seaonsal amplitude (peak-trough difference) of 14.8 ppm, which was approximately threefold that global mean CO₂ observed in Mauna Loa in the United States (MLO). The seasonal variation of CO₂ were mostly dominant by terrestrial carbon fluxes, i.e., net ecosystem procution (NEP) and gross primary produciton (GPP), with correlation coefficient(r) were −0.55 and −0.60 for NEP and GPP, respectively. However, the influence of carbon fluxes on CO₂ were not significant at interannual scale, which implyed that the inter-annual changing trends of atmospheric CO₂ in Northern Hemisphere were likely to depend more on anthropogenic CO₂emissions sources than on ecosystem change. It was estimated, by fitting a harmonic model to monthly-mean ACTE, that both annual mean and seasonal amplitude of ACTE increased over the 10-year period at rates of 2.04 and 0.60 ppm yr⁻¹, respectively. The uptrend of annual ACTE could be attributed to the dramatic global increase of CO₂ emissions during the study period, whereas the increasing amplitude could be related to the increases in Northern Hemisphere biospheric activity. This study also found that the annual CO₂ concentration showed large variation among ecosystems, with the high value appeared in deciduous broadleaf forest, evergreen broadleaf forest and cropland. We attribute these discrepancies to both differential local anthropogenic impacts and carbon sequestration abilities across ecosystem types.

Keywords

• CO₂ concentration
• Terrestrial ecosystem
• Carbon flux
• Eddy covariance technique

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• ∗ 
  Corresponding author.

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