Scaling of increased dissolved organic carbon inputs by forest clear-cutting – What arrives downstream?

• Published in: Journal of hydrology (Amsterdam) 2014-01, Vol.508, p.299-306
• Main Authors: Schelker, Jakob, Öhman, Karin, Löfgren, Stefan, Laudon, Hjalmar
• Format: Article
• Language: English
• Subjects: Boreal forest; Clear-cutting; Dissolved organic carbon; Earth sciences; Earth, ocean, space; Exact sciences and technology; Forest Science; Harvesting threshold; Hydrology. Hydrogeology; Scaling; Skogsvetenskap
• ISSN: 0022-1694; 1879-2707; 1879-2707
• DOI: 10.1016/j.jhydrol.2013.09.056

•Final-felling increases DOC concentrations in downstream rivers.•Concentration increases dependent on the percentage clear-cut area.•Lakes and ponds may attenuate the downstream effects.•Significant increases occur if more than 11–25% are final-felled.•Threshold values could be used to minimize the negative effects. Forest clear-cutting has been found to significantly increase concentrations of dissolved organic carbon (DOC) in boreal first-order streams. Here, we address the questions of (1) how the additional inputs of DOC by upstream forest harvesting affect downstream locations within a stream network and (2) what catchment area has to be harvested to cause a significant downstream increase in DOC concentration. We combined the use of primary data from a paired-catchment experiment, clear-cut history of a nested stream network derived from satellite images with a mixing-model approach in order to quantify the importance of upstream clear-cuts on two downstream sites with different catchment sizes. Modeled [DOC] agreed well with the measured concentrations in the smaller, 8.7km2 catchment located above a larger wetland area, but discrepancies occurred for the larger 22.9km2 catchment located downstream of the wetland. Estimates of the critical area (Acritical) needed to be harvested to cause a significant impact on downstream DOC concentrations was quantified to be 11% for p