Yield models for commercial willow biomass plantations in Sweden

A yield model for willow plantations for bioenergy production in Sweden was developed based on recorded production of 2082 commercial plantations during the period 1989–2005. The model predicts yield for the first, second and third harvest using oats (avena) production as agro-climatic index. The mean annual yields were 2.6, 4.2 and 4.5 oven dry tonnes (odt) per hectare during the first, second and third cutting cycles, respectively. The yield correlated inversely with the length of the cutting cycle. The results of the study show significant differences between growers, which suggest the importance of proper management in the establishment and tending of the plantations. Model estimates for 25% of the best growers vary from 4.0 to 6.3 odt ha−1 yr−1 in 5-year-rotation plantations during the first cutting cycle, and from 5.4 to 7.1 odt ha−1 yr−1 in 4-year-rotations for the second cutting cycle. The proposed model can be applied in policy making and for management planning.