Woody Vegetation Dynamics Beyond the Treeline: Identifying Limiting Processes and Their Tipping Points

This is the authors' abstract. We don't add key points for this paper.

Seasonally snow‐covered arctic and alpine ecosystems are among the fastest‐warming regions on Earth and are undergoing rapid ecological reorganization. Although satellite observations reveal widespread greening, increasing evidence highlights spatial heterogeneity, with instances of localized browning and biomass decline. These spectral trends reflect multiple ecological processes, among which shrub dynamics are an important component. The mechanisms underlying these divergent trajectories remain poorly understood. Snowpack serves a vital buffer, mitigating cold stress by insulating woody vegetation from freezing temperatures and regulating hydrological processes during the growth season. Declining snow depth, earlier melt, and more frequent winter thaw events compromise this buffer, exposing shrubs to intensified freeze–thaw cycles, frost drought, and hydraulic failure. These stresses can locally reduce xylem function, compromise cellular integrity, impair shoot survival, and trigger dieback, potentially pushing shrub communities toward thresholds of decline or reorganization. Interpreting the mismatch between greening trends and localized dieback requires a mechanistic, multi‐scale framework integrating dendrochronology, ecophysiology, and remote sensing. Linking physiological thresholds, such as frost tolerance and damage, to long‐term growth patterns preserved in stem rings, alongside broad‐scale trends captured via remote sensing, provides insight into how snowpack decline shapes woody vegetation dynamics. Such integration is essential to reconcile plant‐level stress responses with biome‐scale changes and improve predictions of vegetation dynamics under ongoing climate warming.