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Sampling procedure in a willow plantation for estimation of moisture content

Nielsen, Henrik Kofoed, Lærke, Poul Erik, Liu, Na, Jørgensen, Uffe
Biomass and bioenergy 2015 v.78 pp. 62-70
clones, coppicing, energy content, harvest date, heat, shoots, stumps, uncertainty, wages and remuneration, water content, wood quality
Heating value and fuel quality of wood is closely connected to moisture content. In this work the variation of moisture content (MC) of short rotation coppice (SRC) willow shoots is described for five clones during one harvesting season. Subsequently an appropriate sampling procedure minimising labour costs and sampling uncertainty is proposed, where the MC of a single stem section with the length of 10–50 cm corresponds to the mean shoot moisture content (MSMC) with a bias of maximum 11 g kg−1. This bias can be reduced by selecting the stem section according to the particular clone. The average difference in MSMC between the largest and smallest shoot in a stump was 31 g kg−1. This variation is only marginally smaller than the variation found in MC between stumps. The MC of individual stem sections may vary as much as 190 g kg−1 in one shoot. Variation in whole shoot moisture content was primarily influenced by the shoot diameter, but in addition significant effects of clone and shoot age were found.