Soil and soil-water chemistry below different amounts of logging residues at two harvested forest sites in Sweden

Abstract

Logging residues (LR),i.e. tops, branches, and needles, are increasingly being harvested for energy production in Fennoscandia. These residues are temporarily piled on site awaiting transport. This study was undertaken to investigate effects on the soil and soil-water chemistry below different amounts of LR at two recently harvested coniferous sites in Sweden. Seven treatments were included and the studied amounts of LR ranged from no LR left on the ground to four times the estimated LR amount of the harvested stands. Two treatments included eight times the estimated LR amount of the harvested stands but here the LR were removed after 7 or 20 weeks. Soil-water samples were collected during the first six or seven growing seasons. Effects of treatment were detected in the soil water for 11 chemical variables at the northern site, and for the NO and Cl concentrations at the southern site. The strongest response was generally found in the treatment with four times the estimated LR amount, for which the highest concentrations were recorded in most cases. In the first three seasons, the water flux through the LR decreased with an increasing amount of residue. Effects on the exchangeable store of Ca in the mor layer and the upper 20 cm of the mineral soil was detected at both sites. At the northern site, the weight of the remaining LR, ground vegetation and all other material above the mor layer in the treatments with two and four times the estimated LR amount was roughly twice the corresponding weights at the southern site seven years after treatment. Although strong effects on the soil-solution chemistry were detected at one of the study sites, in the treatments corresponding to two and four times the estimated logging residue amount, the effect on the leaching from an entire regeneration area is likely to be relatively small given the percentage of the area hosting these logging residue amounts (ca. 20% after stem-only harvesting and 9% after fuel-adapted felling). 3--2+

Changes in Macronutrient Concentrations in Soil Solution Following Regeneration Felling in Pine and Spruce Stands: Whole-Tree Harvesting Versus Stem-Only Harvesting

“…The nutrient concentration often returns to pre-cutting levels within relatively short time, normally 3-5 years, especially if clear-cut is performed without any other disturbances (Raulund-Rasmussen et al, 2011). Even if soil-water chemistry is affected by the residue treatments, the response tends to differ between the sites (Ring et al, 2015). We detected a strong response in nutrient concentrations following regeneration felling in the all three sites (except SOH plot in Oxalidosa turf.…”

Critical biomass harvesting – Applying a new concept for Swedish forest soils

“…Ring et al (2016) demonstrated in an experiment lower NO 3 concentrations in soil solution after whole-tree harvesting than after conventional harvesting. In Ring et al (2015) one of the two investigated sites showed decreasing NO 3 concentrations with decreasing amount of logging residues left on the clearcuts, whereas the other showed no such tendency. de Jong et al (2017) concluded in a synthesis article that whole-tree harvesting leads to no or a slightly decreased risk of N leaching.…”

Long-term effects on soil-water nitrogen and pH of clearcutting and simulated disc trenching of previously nitrogen-fertilised pine plots

“…The pH was analysed to indicate possible impacts on nitrification by which H + is produced along with NO 3 -(cf. Ring et al 2015). Furthermore, changes in pH may affect the leaching of Al and Cd (Berggren 1992;Bergkvist 2001).…”