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Precipitation and net ecosystem exchange are the most important drivers of DOC flux in upland boreal catchments
Author(s) -
Pumpanen Jukka,
Lindén Aki,
Miettinen Heli,
Kolari Pasi,
Ilvesniemi Hannu,
Mammarella Ivan,
Hari Pertti,
Nikinmaa Eero,
Heisalo Jussi,
Bäck Jaana,
Ojala Anne,
Berninger Frank,
Vesala Timo
Publication year - 2014
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2014jg002705
Subject(s) - environmental science , surface runoff , eddy covariance , dissolved organic carbon , hydrology (agriculture) , ecosystem respiration , primary production , precipitation , ecosystem , boreal , ecology , geography , geology , geotechnical engineering , meteorology , biology
According to recent studies, dissolved organic carbon (DOC) concentrations in rivers throughout the boreal zone are increasing. However, the mechanistic explanation of this phenomenon is not yet well known. We studied how the short and long‐term changes in precipitation, soil temperature, soil water content, and net ecosystem exchange (NEE) are reflected to DOC concentrations and runoff DOC fluxes in two small forested upland catchments in Southern Finland. We used continuous eddy covariance measurements above the forest and runoff flow measurements from the catchment areas conducted over a 15 year long time period to study the correlation between NEE, gross photosynthetic production, total ecosystem respiration, litter production, and runoff DOC. In addition, we looked for the most important environmental variables in explaining the interannual changes in runoff DOC by using multiple linear regression. Finally, we studied the temporal connection between runoff DOC concentrations, precipitation, soil water content, and NEE by using wavelet coherence analysis technique. Our results indicate that the DOC concentrations have increased over the last 15 years. The DOC flux was to a large extent determined by the amount of precipitation, but the previous year's NEE and litter production had also a small but significant effect on runoff DOC fluxes.