In this report, literature-based information and expert elicitation are used to define (a) components of sensitivity and exposure to climate change and (b) the capacity of these ecosystems to adapt to expected changes. Aspen ecosystems benefit from fire and quickly reproduce. Yet, aspen trees are susceptible to drought and heat that is projected to become more frequent and intense in the future. Some aspen-associated plant and animal species may benefit from the expected changes in disturbance regimes and stand structure, while others may experience population reductions or stress as a result of drought and heat. Overall, vulnerability is defined as moderate because although persistence of aspen ecosystems is likely, a dynamic spatial and temporal response to climate change is expected.