Print PageProjections of ecosystem responses to climate change are increasingly important for informing adaptation strategies. One way in which climate change may affect vegetation is via its influence on the fire regime. In the US Southeast, hotter, drier conditions may lead to more wildfires, which would affect the structure of vegetation. As part of the USGS’s Southeast Regional Assessment Project, we investigated the potential effects of climate change on the fire regime and subsequent impacts on vegetation dynamics through the year 2060 for ecosystems in the Southeast Coastal Plain. We asked: (1) How will climate change likely impact the annual area burned by wildfires over time? (2) How will this impact on the fire regime affect modeled vegetation dynamics? To determine the potential impact of climate change on the area burned by wildfires, we developed an empirical relationship between past wildfire occurrence and climate. We then projected that relationship to 2060 for the A1FI climate change scenario. We accounted for uncertainty in climate projections by using the 5th, 50th and 95th percentile prediction intervals from Bayesian Model Averaging of climate model output. The result was a set of projections of future area burned in the region. We incorporated those projections into spatially-explicit state-and-transition models of vegetation succession and disturbance. We adjusted the probability of wildfire in the models to reflect climate change effects.
Results/Conclusions
Our modeled relationships suggest that under climate change, the area burned in the region will increase on average, but will range from 0.5 to 3 times the current level. Vegetation dynamics models show a variety of impacts of increased fire for different ecosystems. One noteworthy effect of the increase in fire is that region wide, the composition of fire-dependent ecosystems such as upland longleaf pine shifts toward a more open-canopy structure, which provides critical habitat for wildlife. However, given the level of anthropogenic fire suppression in the Southeast, our results suggest that open stands will still be relatively uncommon in 2060, compared to historic conditions. In summary, our results suggest that one effect of climate change in the Southeast will be an increase in wildfire, which will have varied effects on ecosystems but will be minor in comparison to the effects of anthropogenic influences on the fire regime. In addition, our spatially-explicit projections of vegetation dynamics in the region will be useful tools for informing conservation planning decisions.
