Effect of harvesting method on the amount of logging residues in the thinning of Scots pine stands

Whole-tree harvesting is an increasingly common harvesting method due to the high demand for fuel chips. In whole-tree harvesting, nutrient removal from the site is substantially higher than in cut-to-length harvesting, in which nutrient-rich branches and unmerchantable top sections of trees are left in the cutting area. There is a concern that whole-tree harvesting impairs site productivity, especially on mires drained for forestry. We employed six field experiments to study the effects of the harvesting method used on the amount of logging residues left on the site in the thinning of Scots pine (Pinus sylvestris L.) stands. The four harvesting treatments varied in their intensity of biomass removal from conventional stem-only harvesting (CTL), where tree tops and branches were left on the site to whole-tree harvesting (WTH) complemented by the manual collection of residues. Logging residues left on the sites were weighed and sampled to determine their moisture content. After CTL, the amount of logging residues left on the site was 7780-15340 kg ha−1(dry mass), depending on the experiment. In (WTH) the amount of logging residues left on the site was 32-66% of that of CTL. After the manual collection of residues in WTH, 4-16% of the residues still remained on the sites. The residues left at site following WTH had a larger share of small-diameter material than after CTL.