| Summary: | Fire activity has increased in interior Alaska in recent decades and these trends are projected to continue under climate change. A greater frequency and severity of wildfires have been found to favor broadleaf-deciduous species across numerous field and modeling studies, impacting the resilience of black spruce forests and potentially impacting the carbon storage capacity in the region. This dissertation explores potential future trends in boreal forest fire regimes, vegetation composition, and carbon storage under climate change through three studies using the spatially explicit landscape simulation model, LANDIS-II. The modeling framework represented wildfire dynamically using the SCRPPLE fire extension and captured belowground carbon, hydrologic, and permafrost dynamics in addition to vegetation growth using the DGS succession extension. All three studies relied on simulations of a 380,400-hectare landscape (4-ha resolution) under both historic and future (RCP 8.5) climate projections. The first study explored impacts of wildfire under different climate change scenarios and found that annual area burned and average fire size were greater under climate change; climate change scenarios also resulted in a greater rate of areas burning multiple times during the simulation period. The second study focused on quantifying and identifying drivers of potential shifts in dominant forest type following different numbers of wildfires. It showed that initially-conifer-dominated areas on the landscape that experienced greater numbers of fires more often shifted to broadleaf-deciduous dominance, and this effect was exacerbated by climate change. Vegetation type transitions away from conifer dominance were most strongly driven by percentage of biomass removed in the most recent wildfire. The third study quantified differences in carbon pools and vegetation productivity under different climate scenarios and found that while carbon and net primary productivity overall increased across the landscape under climate change, the ...
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