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Abstract

Area burned by wildfire has increased in British Columbia, Canada, over the past decade. Because of the increase in wildfire activity, forest managers are increasingly interested in understanding post-fire species composition shifts and the drivers influencing post-fire regeneration in British Columbia. I used data collected on post-fire regeneration from 17 fires that burned on the Fraser Plateau between 2009 and 2017, including the Hanceville Complex and the Plateau Complex, two of the largest wildfires in British Columbia documented history. I used pre-fire Vegetation Resources Inventory data to compare pre-fire overstory composition to post-fire seedling composition to quantify and characterize species composition shifts pre- to post-fire for lodgepole pine, interior Douglas-fir, aspen, and interior spruce. Conifer regeneration was present on 778 of the 811 (95.9%) study plots, suggesting that post-fire recovery processes are intact, and that widespread regeneration failure in this region seems unlikely. The majority of plots shifted in composition of at least one species, with increases in lodgepole pine dominance being the most notable. To investigate and identify drivers of post-fire regeneration on the Fraser Plateau, I used logistic regression to build models for identifying the relationships between lodgepole pine and interior Douglas-fir regeneration occurrence and stand structure, site characteristics, and climate variables. Stand structure models had the highest accuracy out of all variable groups, with pre-fire species composition being a highly significant predictor variable in the models for both species. Distance to live tree was a significant predictor for Douglas-fir but it was not significant for lodgepole pine, reflecting different fire adaptations between species and the need for species-specific post-fire management and regeneration efforts. Generally, trees are regenerating well after fire in this region, but forest managers should consider planting interior Douglas-fir on suitable sites if the survival of seed trees is insufficient for natural regeneration. Additionally, a spatially and temporally diverse post-fire monitoring system would provide much needed information for forest managers about the changes and trajectories of post-fire forests.