Biophysical controls on CO2 fluxes of three Northern forests based on long-term eddy covariance data

F. Lagergren, A. Lindroth, Ebba Dellwik, Andreas Ibrom, H. Lankreijer, S. Launiainen, M. Mölder, P. Kolari, Kim Pilegaard, T. Vesala

    Research output: Contribution to journalJournal articleResearchpeer-review


    Six to nine years of net ecosystem carbon exchange (NEE) data from forests in Hyytiala in Finland, Soro in Denmark and Norunda in Sweden were used to evaluate the interannual variation in the carbon balance. For half-monthly periods, average NEE was calculated for the night-time data. For the daytime data parameters were extracted for the relationship to photosynthetic active radiation (PAR). The standard deviation of the parameters was highest for Norunda where it typically was around 25% of the mean, while it was ca. 15% for Hyytiala and Soro. Temperature was the main controller of respiration and photosynthetic capacity in autumn, winter and spring but explained very little of the interannual variation in summer. A strong correlation between respiration and photosynthesis was also revealed. The start, end and length of the growing season were estimated by four different criteria. The start date could explain some of the variation in yearly total NEE and gross primary productivity (GPP) in Hyytiala and Soro, but the average maximum photosynthetic capacity in summer explained more of the variation in annual GPP for all sites than start, end or length of the growing season.
    Original languageEnglish
    JournalTellus B: Chemical and Physical Meteorology
    Issue number2
    Pages (from-to)143-152
    Publication statusPublished - 2008


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