Variability in exchange of CO2 across 12 northern peatland and tundra sites

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Many wetland ecosystems such as peatlands and wet tundra hold large amounts of organic carbon (C) in their soils, and are thus important in the terrestrial C cycle. We have synthesized data on the carbon dioxide (CO2) exchange obtained from eddy covariance measurements from 12 wetland sites, covering 1-7 years at each site, across Europe and North America, ranging from ombrotrophic and minerotrophic peatlands to wet tundra ecosystems, spanning temperate to arctic climate zones. The average summertime net ecosystem exchange of CO2 (NEE) was highly variable between sites. However, all sites with complete annual datasets, seven in total, acted as annual net sinks for atmospheric CO2. To evaluate the influence of gross primary production (GPP) and ecosystem respiration (R-eco) on NEE, we first removed the artificial correlation emanating from the method of partitioning NEE into GPP and R-eco. After this correction neither R-eco (P = 0.162) nor GPP (P = 0.110) correlated significantly with NEE on an annual basis. Spatial variation in annual and summertime R-eco was associated with growing season period, air temperature, growing degree days, normalized difference vegetation index and vapour pressure deficit. GPP showed weaker correlations with environmental variables as compared with R-eco, the exception being leaf area index (LAI), which correlated with both GPP and NEE, but not with R-eco. Length of growing season period was found to be the most important variable describing the spatial variation in summertime GPP and R-eco; global warming will thus cause these components to increase. Annual GPP and NEE correlated significantly with LAI and pH, thus, in order to predict wetland C exchange, differences in ecosystem structure such as leaf area and biomass as well as nutritional status must be taken into account.


  • Magnus Lund
  • Peter M. Lafleur
  • Nigel T. Roulet
  • Anders Lindroth
  • Torben Christensen
  • Mika Aurela
  • Bogdan H. Chojnicki
  • Lawrence B. Flanagan
  • Elyn R. Humphreys
  • Tuomas Laurila
  • Walter C. Oechel
  • Janusz Olejnik
  • Janne Rinne
  • Per Schubert
  • Mats B. Nilsson
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Geography


  • tundra, wetland, respiration, photosynthesis, peatland, net ecosystem exchange, mire, eddy covariance, carbon, carbon dioxide
Original languageEnglish
Pages (from-to)2436-2448
JournalGlobal Change Biology
Issue number9
Publication statusPublished - 2010
Publication categoryResearch