Across mountain regions globally, forest ecosystems are experiencing intensifying environmental pressures that alter their structure and function. Understanding how these ecosystems respond is critical for predicting and managing integrated watershed function. Plant communities—through demographic processes, functional trait assembly, and self-organization—can serve as sensors of emerging environmental stress. Plant responses to stressors including increasing temperature, reduced snowpack, early snowmelt, and rising vapor pressure deficit provide essential information about the mechanisms of ecosystem resistance and resilience, as well as ecological tipping points and biotic refugia. This session highlights innovative approaches to understanding interactions between landscape physiography and vegetation dynamics, with a focus on functional traits and their plasticity. We welcome contributions that address watershed-specific challenges, including warming, drought, and changing snow dynamics through in situ plant trait observations, demographic measurements, remote sensing, and modeling. Special attention is given to studies that integrate aboveground and belowground processes.