Willow Short-Rotation Production Systems in Canada and Northern United States: A Review

Willow (Salix spp.) short-rotation coppice (SRC) systems are becoming an attractive practice because they are a sustainable system fulfilling multiple ecological objectives with significant environmental benefits. A sustainable supply of bioenergy feedstock can be produced by willow on marginal land using well-adapted or tolerant cultivars. Across Canada and the northern United States, there are millions of hectares of available degraded land that have the potential for willow SRC biomass production, with a C sequestration potential capable of offsetting appreciable amounts of anthropogenic greenhouse gas emissions. A fundamental question concerning sustainable SRC willow yields was whether long-term soil productivity is maintained within a multi-rotation SRC system, given the rapid growth rate and associated nutrient exports offsite when harvesting the willow biomass after repeated short rotations. Based on early results from the first willow SRC rotation, it was found that willow systems have relatively low nutrient demands, with minimal nutrient outputs other than in the harvested biomass. Our overall aim was to summarize the literature and present findings and data from ongoing research trials across Canada and the northern United States examining willow SRC system establishment and viability. The research areas of interest are the crop production of willow SRC systems, above-and belowground biomass dynamics and the C budget, comprehensive soil-willow system nutrient budgets, and soil nutrient amendments (via fertilization) in willow SRC systems. Areas of existing research gaps were also identified for the Canadian context.