Jussi Laurila

Weight and volume of small-sized whole trees at different phases of the supply chain.

Abstract The measurement of the amount of energy wood can be based on volume (m3), weight (kg) or energy content (MWh). All of the previous units of measurement are being used today. However, measuring wood is problematic. Physically the measuring can be made in the forest, at the roadside storage site or at the heating plant. Nowadays crane scale weighing in the forest is the commonly used and accepted technique. In this study the differences, variations and correlations between the different energy wood measurement methods are examined. The whole supply chain from the forest to the heating plant was tracked. The material was collected from young stands and it was based on about 14,300 m3 solid (12.7 million kg) energy wood from 75 worksites. There was a strong correlation (r 2=0.87–0.98) between the values given by the different measurement methods throughout this study, although a remarkable weight loss (37%) between the forest and the heating plant was observed. Moreover, the solid volume factor 0.49 with SD 0.07 between the chips loose volume and the calculated solid volume, based on the crane scale, was higher than the 0.40 factor that is normally used in practice.

The effect of girdling on the moisture content of small-sized trees

In this study, the effect of girdling on the moisture content of small-sized trees for heat energy production was clarified. The moisture content was measured for Scots pine (Pinus sylvestris), Norway spruce (Picea abies), and Downy birch (Betula pubescens) during two growing seasons after girdling. The trees were girdled at breast height for around 30 cm by removing the bark, phloem, and cambium from around the stem. At the beginning of the growing season the mean moisture content of the living Scots pine (P. sylvestris) and Norway spruce (P. abies) was 60%, and for Downy birch (B. pubescens) it was 50%. During the first growing season the effect of girdling on the moisture content was low, but during the second growing season the moisture content decreased significantly. The moisture content of the Norway spruce (P. abies) (23%) and Downy birch (B. pubescens) (33%) was at its lowest point at 14 months after girdling. There were no significant changes in the moisture content of the Scots pine (P. sylvestris) in this study. The results of this study can be used in basic research and in the development of energy wood production.

Kuusen kantojen kosteus päätehakkuualoilla ja tienvarsivarastoissa

Seloste artikkelista: Laurila, J. & Lauhanen, R. / Moisture content of Norway spruce stump wood at clear cutting areas and roadside storage sites. Silva Fennica 44 (2010) : 3, 427-434.