Bioenergy Production and Soil Sustainability In the Pacific Northwest.

Though it has often been couched in other terms, the basis of sustainability of bioenergy production in the Pacific Northwest is primarily soil-centered, dependent on the extent and avaialability of soil nutrient pools. Some PNW forest soils are very low in total and available nutrients relative to the current pools and inputs, and would be sensitive to normal harvesting, whereas many soils are very rich in nutrients relative to intensive removals, and are very resilient to high rates of biomass removal. Research at Fall River, Matlock and Molalla long-term soil productivity projects show high resilience based on soil nutrient levels in the PNW, though other work in 72 forest sites from northern Vancouver Island, Canada to southern Oregon show a wide range of soil nutrient pools, and potentially-sensitive sites. Some fire-driven systems would benefit from removal of biomass for bioenergy by reducing susceptibility to fire. In nearly all cases, high rates of biomass removal can substitute for loss of additional nutrients relative to tree growth; however, environmental and social considerations are typically the driving forces that limit expansion of biomass-to-energy growth in the region.