Wildfire is a growing concern throughout the world, both due to increases in area burned and fire severity and to the high costs associated with fire suppression. This trend will likely continue as temperatures rise and precipitation patterns change. Fuel treatments, including mechanical removal of trees and prescribed burning, are known to be effective in reducing wildfire behavior, particularly in forests that were historically dominated by frequent fire-maintained forest types, but the effectiveness of these treatments is uncertain under climate change. An improved understanding is needed of the factors that influence the effects of fuel treatment on wildfire activity at large spatial scales and over time, accounting for complex interactions among forest dynamics, fire sizes and severities, and the range of projected climate trajectories. We investigated these interactions by simulating forest succession, forest management, and wildfire activity under historical weather and a range of projected future temperature and precipitation conditions in a mixed-conifer landscape in the Blue Mountains region of central Oregon, USA. Forest succession (e.g., tree competition and mortality, carbon and nitrogen cycling) and disturbance (e.g., tree harvest, prescribed burning, and wildfire) were dynamically modeled over the period of 2010 to 2100 to produce emergent changes in the fire regime and species distributions.
Results/Conclusions
Preliminary results show that under climate change, the fire rotation period decreased by at least 5%, with an equivalent increase in average annual area burned and mean fire size. Fire severity, measured through tree mortality, was generally moderate with both low and high severity fires occurring under all climate scenarios. Mean fire severity increased during the first several decades, with the magnitude dependent on climate scenario, and in some cases decreased thereafter due to a reduction in available fuels. Species shifts under climate change reflected both elevation gradients and fire interactions. Shade-tolerant/fire-intolerant species declined in distribution, and shade-intolerant/fire-tolerant conifer species increased under all scenarios. The results of this study offer insight to the applicability of current forest management practices as the climate warms and helps to inform decision-making by identifying trends in species and fuelbeds that will affect future fire.