Wood and bark of some poplar and willow clones as fuelwood

Poplars and willows are widely used to produce biomass for energy. Calorific values of wood and bark, as well as for whole tree of Populus x euramericana (cl. I-214), Populus deltoides (cl.PE 19/66) and white willow Salix alba (cl.378) of different ages were determined. one- and 2-year-old rooted cuttings were grown in plantations with high planting density, in order to produce a high biomass yield per hectare. Mature trees in both species (poplar and willow) originated from the corresponding plantations; willow 14-year old, and poplar 12 years (cl.1-214) and 8 years (cl.PE 19/66). As the share of bark depends on the age of wood, calorific values were determined separately for bark and for wood. The share of bark (proportion of total weight) in 1- and 2-year-old rooted cuttings ranged between 18% and 27%, and in older trees it was from 10% to 15%. The higher heating values of oven dry poplar wood (calculated for the whole tree, based on the proportion of bark) were from 15,787 (cl.1-214 1-year old) to 24,275 kJ/kg (cl.1-214 2-year old). The average calorific values of willow wood (whole tree with bark) were from 16,169 (14-year old) to 22, 572 kJ/kg (2-year old). It should be pointed out that the calorific value of wood is more favorable than that of bark, and the highest calorific values refer to 2-year-old trees. (C) 2002 Elsevier Science Ltd. All rights reserved.