Dry forest resilience varies under simulated climate-management scenarios in a central Oregon, USA landscape

Determining appropriate actions to create or maintain landscapes resilient toclimate change is challenging because of uncertainty associated with potential effects ofclimate change and their interactions with land management. We used a set of climateinformedstate-and-transition models to explore the effects of management and naturaldisturbances on vegetation composition and structure under different future climates. Modelswere run for dry forests of central Oregon under a fire suppression scenario (i.e., nomanagement other than the continued suppression of wildfires) and an active managementscenario characterized by light to moderate thinning from below and some prescribed fire,planting, and salvage logging. Without climate change, area in dry province forest typesremained constant. With climate change, dry mixed-conifer forests increased in area (by anaverage of 21–26% by 2100), and moist mixed-conifer forests decreased in area (by an averageof 36–60% by 2100), under both management scenarios. Average area in dry mixed-coniferforests varied little by management scenario, but potential decreases in the moist mixedconiferforest were lower with active management. With changing climate in the dry provinceof central Oregon, our results suggest the likelihood of sustaining current levels of dense, moistmixed-conifer forests with large-diameter, old trees is low (less than a 10% chance) irrespectiveof management scenario; an opposite trend was observed under no climate changesimulations. However, results also suggest active management within the dry and moistmixed-conifer forests that creates less dense forest conditions can increase the persistence oflarger-diameter, older trees across the landscape. Owing to projected increases in wildfire, ourresults also suggest future distributions of tree structures will differ from the present. Overall,our projections indicate proactive management can increase forest resilience and sustain somesocietal values, particularly in drier forest types. However, opportunities to create moredisturbance-adapted systems are finite, all values likely cannot be sustained at current levels,and levels of resilience success will likely vary by dry province forest type. Land managersplanning for a future without climate change may be assuming a future that is unlikely to exist.