Biochar as a soil amendment in northern forests: ecology, biogeochemistry, and bioenergy tradeoffs

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Biochar-bioenergy systems have recently been heralded as one of the few technologies with substantial promise not only to reduce fossil fuel usage, but also to directly mitigate anthropogenic climate change by enhancing carbon sequestration. While promising, research on biochar-bioenergy systems is in its infancy. The research proposed here explores biochar-bioenergy systems in Canada's forestry sector in order to add environmental and economic value to renewable energy production with forest biomass and to improve the sustainability of forest harvesting. We have previously established a research-scale pyrolysis system at Haliburton Forest and Wildlife Reserve Ltd to produce biochar from wood chips and other mill residues (e.g., sawdust, bark) under controlled conditions. Forests in this region are strongly phosphorus limited, likely as a result of chronic nitrogen deposition, and also show co-limitation bycalcium. Under these soil conditions, biochar, which increases soil pH and increases soil P availability, may act as a cost-effective forest soil amendment that can potentially increase productivity and enhance environmental services such as carbon sequestration. The proposed work brings together scientists with a strong track record in forest ecosystem dynamics, soil processes, chemical characterization of wood breakdown products, and biodiversity assessment. We will address key unknown questions regarding how different types of biochar produced with forest biomass influence soil fertility and carbon cycling and, in turn, influence plant and stand dynamics. Any positive or negative impacts of biochar on above- and below-ground biodiversity will also be characterized and solutions sought to minimize impacts. In addition life cycle analysis will be used to determine the holistic carbon, energy, and economic costs of benefits of biochar bioenergy systems. There are essentially no prior studies on biochar as a soil amendment in temperate forest soils: the integration of approaches here will thus offer an unprecedented increase in the knowledge base in this area.