Northern latitudes are experiencing more rapid increases in temperature than other parts of the globe, leading to more frequent wildfires in boreal forests. Historic fire regimes have historically played an important role in boreal forests by maintaining dominance of black spruce, however, recent increases in fire frequency are creating shorter intervals between fires at many locations throughout interior Alaska. This change in the fire regime may alter boreal forest successional trajectories, with multiple mechanisms and feedbacks at play. Previous studies from boreal forests have shown that areas experiencing short-interval fires favor regeneration of deciduous species, creating conditions that remove competitive advantages of black spruce. It remains unclear how a shift from conifer dominance would impact long-term species composition and landscape patterns, and how other processes (e.g. permafrost thawing) could interact with these outcomes. The objectives of this study are to understand how a short-interval fire regime along with climate change will impact vegetation community composition in interior Alaska through time. We used LANDIS-II to simulate forest succession over the next century with dynamic wildfire under historic and climate change scenarios. Growth was calibrated using field measurements from FIA plots and wildfire was calibrated using publicly available daily fire perimeter data.
Results/Conclusions
Preliminary modeling results show single fire events maintaining dominance of black spruce at locations where black spruce was initially dominant. However, multiple fire events within a short period of time (75 years) showed a lower proportion of areas returning to black spruce dominance following the most recent fire event. When areas burned multiple times within the same period, black spruce biomass declined as the number of fires increased (given the same recovery period of 25 years), while deciduous species like paper birch biomass increased under the same circumstances. These initial results show the potential for a shift in species dominance within the boreal forest under a more frequent fire regime. Changes in species composition in the boreal forest have implications for permafrost dynamics, belowground soil processes and the global carbon cycle.