Modelling the effects of forest management intensification on base cation concentrations in soil water and on tree growth in spruce forests in Sweden

The study investigated the effects of forest residue extraction on tree growth and base cations concentrations in soil waterunder different climatic conditions in Sweden. For this purpose, the dynamic model ForSAFE was used to compare theeffects of whole-tree harvesting and stem harvesting on tree biomass and the soil solution over time at 6 different forestsites. The study confirmed the results from experimental sites showing a temporary reduction of base cation concentrationin the soil solution for a period of 20–30 years after whole-tree harvesting. The model showed that this was mainly causedby the reduced inputs of organic material after residue extraction and thereby reduced nutrient mineralisation in the soil. Themodel results also showed that whole-tree harvesting can affect tree growth at nitrogen-poor forest sites, such as the ones innorthern Sweden, due to the decrease of nitrogen availability after residue removal. Possible ways of reducing this impactcould be to compensate the losses with fertilisation or extract residue without foliage in areas of Sweden with low nitrogendeposition. The study highlighted the need to better understand the medium- and long-term effects of whole-tree harvestingon tree growth, since the results suggested that reduced tree growth after whole-tree harvesting could be only temporary.However, these results do not account for prolonged extraction of forest residues that could progressively deplete nutrientpools and lead to permanent effects on tree growth