Recent impacts of climatic change across the western United States have reduced live tree carbon, increased tree mortality, and increased the frequency of extreme fire weather events. Projections for the region suggest the conifer forests of the west will continue to decline in the face of pervasive drought stress and increasing wildfire size, consequently increasing carbon instability across the region. The effects of wildfire on tree mortality and carbon loss can be moderated by using combinations of mechanical thinning and prescribed burning to restore the frequent fire adapted dry forests of the western US. However, the practical limitations of large scale treatment application preclude entire landscapes from receiving the required level of restoration treatments to ensure wildfire resilience. Our goal was to investigate how optimizing fuels treatment placement could reduce area impacted by high-severity wildfire in a watershed in the Sierra Nevada under projected climate. We ran LANDIS-II simulations using ensembles of projected climate from CMIP5, under two management conditions: uninformed and optimized, with respect to forest thinning and prescribed burning, where ecologically appropriate. The optimized treatment placements were based on the vulnerability of parts of the landscape to high-severity fire
Results/Conclusions
Relative to uninformed treatment placement simulations, the informed treatment strategy accumulated significantly more (20%, 18 Mg C ha, p < 0.01) more above ground carbon, with considerably less variation between replicates (uninformed sigma =3, optimized sigma = 0.5). Further, C emissions from wildfire were reduced by 25% relative to uninformed treatment placement. By optimizing treatment placement, we reduced the proportion of the landscape thinned by 20%, and yet still realized increases in above ground carbon stocks, and reductions in wildfire emissions. These differences are due primarily to a reduction in the proportion of the landscape that was impacted by high severity fire (reduction of 16% relative to the uninformed treatment placement). Our results suggest that by informing fuels treatment placement by the vulnerability of the ecosystem to high severity fire, we can increase carbon stability of the ecosystem in the face of increasing wildfire and drought disturbance associated with projected climate.