Braziunas, Kristin H. 2021. Operationalizing resilience of social-ecological systems to changing climate and fire in US Northern Rocky Mountain forests. PhD Dissertation, University of Wisconsin-Madison.

Current rates of change in climate and disturbance threaten ecosystem resilience, and means of operationalizing resilience in real-world landscapes are urgently needed. My dissertation tackles this knowledge gap by using multiple approaches to measure, anticipate, and manage for resilience in ecological systems (forests) and social-ecological systems [forested wildland urban interface (WUI) landscapes]. I investigated how changes in climate and fire affected conifer-dominated forests in the US Northern Rocky Mountains, asking: (1) how well remotely sensed data mapped forest fuels and how burn severity differed between young and mature forests; (2) how potential interactions between fire return interval and post-fire drought affected forest recovery and fuels in paired short- (< 30 year) and long- (> 125 year) interval fires; (3) how fuels treatment effectiveness varied with amount and configuration of houses and under changing climate using a process-based forest simulation model; and (4) how spatially contrasting fuels treatment strategies affected fire safety and forest ecosystem service supply in WUI landscapes. Lidar-imagery fusion accurately predicted forest fuels, and young subalpine forests burned at similar severity as mature forests. Post-fire tree stem density was nearly 10-fold lower following short- versus long-interval fires in subalpine forests; differences between paired plots increased with warmer-drier climate and were amplified farther from live forest. Declines in live fuels following short-interval fire could limit burn severity and fire intensity under increasing fire frequency. Treating approximately 30% of the WUI every 10 years reduced risk even under substantial climate change, and fire risk was lower in clustered versus dispersed WUI developments. However, climate and fire, rather than fuels treatment, were the dominant drivers of future forest ecosystem service supply, with most indicators declining by more than 80% by 2099. My work suggests multiple drivers will act synergistically to reduce forest resilience but increased reburning is likely to limit future fire behavior. WUI protection can meaningfully reduce fire risk but sustaining forest ecosystem services may be unattainable in fire-prone landscapes. If the current climate change trajectory continues, people will need to adapt to new ecosystems and adjust expectations of the services they can provide.