Identifying Indicators of State Change and Forecasting Future Vulnerability in Alaskan Boreal Ecosystems

Abstract : This report summarizes empirical and modeling studies to improve understanding of the mechanistic linkages among fire, vegetation, the soil organic layer, and permafrost thaw across interior Alaska. Primary objectives: (1) Determine mechanistic links among fire, soils, permafrost, and vegetation succession in order to develop and test field-based ecosystem indicators that can be used to directly predict ecosystem vulnerability to state change and (2) Forecast landscape change in response to projected changes in climate, fire regime, and fire management. Results show that increased wildfire severity increases permafrost thaw in the near-term and influences seedling establishment and successional trajectories, shifting forest composition from black spruce ecosystems to those comprised of deciduous tree species. Long term, this shift has consequences for under story moss growth and organic soil re-accumulation, thereby directly influencing permafrost recovery. Forest management approaches employed will also impact successional trajectories and vulnerability of permafrost to thaw.