Throughfall was sampled in each plot with ten systematically distributed bulk collectors of the same type as open field collectors. At every sampling event, the volume collected in each bulk collector was determined and samples were bulked to one sample for precipitation. Samples were treated and analysed as prescribed by the ICP Forests
manual, part XI, XIII and XIV (ICP Forests, 2010). Quality control included the analysis of control samples (blanks, reference material, replicates) and participation in the ICP Forests water and foliar ring tests, according to the guidelines of the ICP Forests manual, part XVI (ICP Forests, 2010). Water samples (500 mL subsamples of each collected
fraction) were kept cool during transportation, filtered (0.45 ?m), stored in darkness at 4 °C and analysed within 48 h after sampling. Concentrations of Total Kjeldahl Nitrogen (TKN) (mg L?1) were determined using the continuous flow method (Skalar, limit of quantification, LOQ = 0.5 mg L?1 ). Concentrations of ammonium (NH4 +) and sodium (Na+) (mg L?1
) were determined using ion chromatography (DionexICS-3000, LOQ = 0.1 mg L?1 ). Concentrations of DOC were determined using a TOC-analyser (Shimadzu TOC 5050 A, LOQ = 0.1 mg L?1 ). pH was measured on unfiltered subsamples (Multi 340i-glass electrode, WTW).