Laitila*, J., Niemistö, P and Väätäinen, K. 2016. Productivity of Multi-Tree Cutting in Thinnings and Clear Cuttings of Young Downy Birch (Betula pubescens) Dominated Stands in the Integrated Harvesting of Pulpwood and Energy Wood. Baltic Forestry 22(1):

   The purpose of this study was to determine the productivity of multi-tree cutting of pulpwood and energy wood in thinnings and clear cuttings of young downy birch (Betula pubescens) dominated stands, along with the time consumption of cutting work phases performed with a medium-sized harvester. On the basis of the time study data collected, tree-specific time consumption and productivity models were prepared for the multi-tree cutting of pulpwood and energy wood in both thinnings and clear cuttings. In the multi-tree cutting time consumption model, productivity was explained in terms of tree volume (dm3) and harvesting intensity (number of trees removed per hectare). Productivity was expressed in solid cubic metres per effective hour (m3/E0h). Harvested assortments in the integrated harvesting included pulpwood with lengths of 3–5m and energy wood, which consisted of undelimbed tops of pulpwood stems and undersized trees. As expected, clear cutting enhanced harvesting productivity in comparison with thinning, but multi-tree cutting had only a minor effect on productivity in the case of both harvesting methods due to the low share of multi-tree cutting. In the time study sample plots, the values recorded for multi-tree cutting productivity per effective hour varied between 5.6–17.4 m3/E0h in clear cuttings and 4.8–10.9 m3/E0h in thinnings, respectively. On average, the harvester head processed 1.2 trees per grapple cycle in clear cutting and 1.1 trees per grapple cycle in thinnings. The study highlighted the need to improve the suitability of current harvesting equipment for the harvesting and multi-tree harvesting of birch and other trees with bent and crooked stems. This is because harvesting conditions that are more favourable to clear cutting than thinning are the main factors behind the observed leap in productivity:

  1. The tree-specific moving time shortened when more trees could be harvested at the same spot than during thinning; 
  2. The removal of trees was systematic in clear cutting whereas it was selective in thinning;
  3. In clear cutting, the remaining tree stand did not hamper the delimbing, cutting or piling of trees.

Keywords: Multi-tree cutting, integrated harvesting, peatlands, downy birch, first thinning, clear cutting, pulpwood, coppice forests.