Soil Fertility and the Sustainability of Short Rotation Woody Crop Production for Bioenergy In Canada.

A national network of short-rotation woody crop (SWRC) research sites has been established for development of fast-growing, high-yield tree species with desirable bioproduct attributes. Lead proponents are the Canadian Forest Service and the Canadian Wood Fibre Centre - FPInnovations, in collaboration with universities, industry, provincial governments, private landowners, and other federal agencies. Research objectives are: 1) production of fast-growing, high-yield woody crops (hybrid poplar, willow) for energy production, and 2) development of management practices advancing sustainable production of SRWC with minimal environmental impacts. Productivity research emphasizes species and clonal suitability, biomass, yield, and fibre attributes. Management regimes on 64 sites in five provinces are: 1) High-yield afforestation: area-based, large-stem stands (1100 - 1600 stems/ha), minimum 20 ha installation, tree size 30 cm diameter and 20 m height over 12 - 20 year rotations, and  2) Concentrated production of small-stem woody biomass: installations less than 1 ha, 15,000 – 20,000 stems/ha, and harvest cycles of 3-4 years with 5 -7 generations for individual coppice systems.

Sustainability research initiated in 2009 is focussed on soil fertility assessments for various SRWC options under a range of climatic conditions and energy opportunities across Canada. Protocols for site establishment, monitoring, management practices, evaluation of site impacts, and productivity assessment are applied consistently. Current research is following changes in soil fertility from site establishment through stand development without nutrient amendments to determine the trajectory of nutrient changes under intensive management, and to determine if, when, and where nutrient amendments should be considered with respect to potential productivity gains, economic costs, and environmental impacts. Preliminary results indicate baseline site differences in soil fertility, and first-year differences in soil nutrients due to planting intensity. Long-term monitoring of other environmental services such as carbon sequestration is done concurrently.