Adaptive silviculture for climate change in North American forests: Operationalizing the...

The impacts of global climate change have compelled forest managers to evaluate their practices and ecosystems, considering when and how to resist change, promote resilience, or facilitate transitions. Forest adaptation has made significant strides to move from theory to practice over the last two decades, with widespread examples of intentional, thoughtful, explicit adaptation. However, very few of these examples exist within a research framework, and their underlying theories of change are unlikely to be rigorously tested. The Adaptive Silviculture for Climate Change (ASCC) Network addresses this science gap, conceived through a process of science coproduction (i.e., translational ecology) to implement a long-term ecological monitoring network and operational-scale (representative of routine practice) experimental trials that test the Resistance-Resilience-Transition (RRT) adaptation framework. Fourteen sites (mean size 160 ha per site) located throughout North America applied a common, replicated study design that translates the RRT framework into treatments localized to forest types, climate-amplified stressors, and forest management regimes. The goal of the study presented here is to examine how climate-adaptive management is implemented across diverse forest ecosystems and evaluate alignment of specific practices (e.g., compositional diversification, structural enhancement, forest assisted migration) in advancing forest adaptation. We conducted a network-wide meta-analysis leveraging field measurements, forest management plans, and structured prompts to assess how site-level ecological characteristics, global change vulnerabilities, management goals, and outcomes differ among RRT treatments compared to business-as-usual forest management (i.e., Common Practice). Results indicate that key adaptation pathways are achieved through modifications in forest composition (e.g., species, functional identity, and adaptive potential or assisted migration), structural characteristics (e.g., relative density, harvest complexity), and achievement of multiple, diverse desired future conditions. Additionally, differences exist among RRT treatments when examined by site-specific conditions, principally associated with dominant overstory type (e.g., angiosperm vs. gymnosperm) or the roles of fire and drought. Despite clear network-wide trends, important differences remain among treatments at the site level, highlighting local, operational variation in theoretical adaptation strategies. The findings of this continental experiment illustrate the flexibility of the RRT adaptation framework and reinforce the need for climate adaptation to be inherently flexible in responding to local needs and new threats.