In recent decades, wildfire size and severity have increased in forests across the Western U.S. as an indirect result of climate change. Changes in wildfire regimes and climate conditions can weaken the mechanisms of forest recovery after fire. For example, increasingly large wildfires can limit tree re-establishment when the surviving seed sources are too far away. Increasingly hot and dry post-fire conditions can further limit tree re-establishment if seedlings become too heat- and drought-stressed. When forests are unable to grow back after fire, they may transition to different vegetation types (e.g., from forest to grassland). Aligning forest management strategies with the range of possible future climate and wildfire trajectories is a key need for supporting forest resilience in the future.

Management guided by the future range of variability creates opportunities for applying the resist-accept-direct (RAD) framework for climate adaptation. RAD considers ‘resisting’ forest loss in areas where drivers of forest resilience are less threatened by changing climate and wildfire conditions, ‘accepting’ forest loss in areas where ecological transformation is inevitable, and ‘directing’ forest change to alternate forms that are resilient to changing climate and wildfire conditions and continue to support ecosystem services.

Partnering with the Washington Department of Natural Resources and the U.S. Forest Service, Sofia will use iLand, a simulation model that models individual tree growth, competition, mortality, and trees’ responses to changes in climate and wildfire. Modeling complex systems built on fine-scale processes with iLand can help with understanding how fire and forest dynamics respond to different management strategies. Sofia will adapt the management component of iLand to strategies followed by state and federal managers in the Pacific Northwest (PNW). Applying the PNW-specific model onto a test landscape in the eastern slopes of the Cascades, this project aims to estimate, over the next century, how existing and experimental management strategies interact with changing climate and wildfire regimes to alter forest cover.

Through this project, Sofia will evaluate how existing management activities (i.e., post-fire planting and pre-fire fuel reduction) as well as experimental activities (i.e., post-fire planting of future climate-aligned varieties of conifers and post-fire fuel reduction) can be used to adapt forests to future conditions and align with the RAD framework for adaptive management planning. This work will culminate in maps of modeled future forest cover across management scenarios for the rest of the century, which could directly assist in prioritizing treatments across a high-priority planning area in eastern Washington. Additionally, forecasted ranges of wildfire size and severity trajectories from modeled scenarios can inform how such treatments may influence wildfire patterns at the landscape scale.