Fluxes of dissolved organic carbon in stand throughfall and percolation water in 12 boreal coniferous stands on mineral soils in Finland

The magnitude and variation in DOC fluxes in bulk deposition (BD), stand throughfall (TF) and percolation water (PW) were determined on seven Scots pine and five Norway spruce plots in Finland during 1998-2004. Water fluxes for PW were calculated using an anion budget method. The relationships between the DOC fluxes and climatic and stand parameters were also investigated. The mean DOC flux in TF varied between 2 and 6 g C m -2 a -1 and between 3 and 8 g C m -2 a -1 on the pine and spruce plots, respectively. The output flux of DOC in PW at the 40-cm depth varied between 1 and 10 g C m -2 a -1 on all the plots. The DOC fluxes in TF and net TF correlated positively with the effective temperature sum and growing season length on the pine and spruce plots, i.e. the highest DOC fluxes were recorded in southern Finland and the fluxes decreased towards the north. The TF and net TF DOC fluxes correlated positively with the amount of precipitation on the pine plots, and the net TF DOC fluxes with the stem volume on the spruce plots.