Pine, spruce and birch logging residues on a clear-cut increase base cations concentrations in soil percolation water along with nitrate concentrations increase

This study's aim was to determine the effect of logging residue piles of Scots pine, Norway spruce and silver birch on the base cation concentrations in percolation water below the rooting depth in a clear-cut. The second aim was to determine if the concentrations of nitrate and dissolved organic carbon were related to the concentrations of base cations in percolation water. A Norway-spruce-dominated stand was clear-cut, and logging residues were taken from spruce, pine, and birch trees from the adjacent and similar forest stand to the clear-cut. Piles containing 40 kg m⁻² of fresh branches were constructed on the soil surface, covering a 60 cm × 60 cm area, i.e. the whole surface area of the lysimeter that was first installed. A zero-tension lysimeter collected soil percolating water through a logging residue pile and soil profile to a depth of 40 cm below the surface of the ground. Percolation water was collected for chemical analysis at 4–6-week intervals during 2016–2017 and the concentrations of calcium, magnesium and potassium were determined. Logging residues of spruce, pine, and birch caused increased concentrations of base cations in percolation water, and the highest concentrations were associated with birch residues. Dissolved organic carbon concentrations were always low and were not correlated with base cations. Logging residues are located to restrict parts of a clear-cut area in large piles, and this causes elevated concentrations of nitrate below the piles: this study showed that nitrate concentrations were related to the elevated concentrations of base cations.