Biochar-based tree seed coatings for climate-smart forest restoration

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Limited seed availability (propagule limitation) and adverse soil conditions at the time of seedling establishment are important impediments to reforestation in northern ecosystems. In large-scale disturbances at remote sites tree planting with locally adapted genetic stock is commonly infeasible or prohibitively expensive. This long-standing challenge in forest restoration and management has taken on new significance from the perspective of "climate-smart forestry": i.e., managing forests to enhance forest resilience and carbon sequestration, and to otherwise mitigate climate change effects. There is recent evidence that pyrolyzed organic matter derived from wood waste material ("biochar") can substantially enhance tree performance, including early seedling development and subsequent tree growth and survivorship. The proposed project seeks to develop and test biochar seed coatings suitable for use in drone-based precision seeding approaches for forest restoration in remote sites in Canada. The proposed objectives of this research are to: (1) Design and test of biochar-based seed coatings based on lab and field studies that will assess effects of alternative biochars, binding agents, and coating thickness on granule mechanical properties, seed germination and early development, and on soil properties important to seedling establishment; (2) Evaluate alternative biochar feedstocks for seed coating applications, including tests of nutrient priming effects and of the "home-field advantage" hypothesis that tree seedlings of fire-adapted species will perform best in biochars from conspecific feedstock; (3) Conduct field trials of simulated and actual drone dispersal of alternative types of biochar seed coatings at sites in Northern BC and Northern Ontario representative of target restoration sites, specifically including large post-fire and similar sites with poor regeneration, and assess results in terms of tree establishment and carbon sequestration outcomes. The project is designed to provide a scientific foundation for new product development by the industrial partners BC Biocarbon and Seed the North, Inc.