Branch Orientation: A Potential Indicator of Stem Rehydration and Water Stress

Spring rehydration in snow‐covered temperate forests marks a key ecohydrological transition, influencing forest productivity and water balance. Tree water deficit is a key ecohydrological indicator about above ground water status and response to subsurface water availability. But simple measures of rehydration and water deficit are few and the relationship between stem rehydration and simple indicators like structural movement linked to branch orientation remains poorly understood. We investigated the coordination between stem rehydration, tree water deficit and branch movement in Abies balsamea using high‐resolution dendrometer data and time‐lapse imagery from early March to mid‐May in Ontario, Canada. In this video and data, we showed that upward branch movement consistently aligned with stem radius expansion during snowmelt and after rainfall events, while downward branch posture corresponded with dry periods and increased tree water deficit. Freeze–thaw events caused abrupt stem shrinkage but had limited influence on branch position. These findings suggest that branch posture reflects stem water status, potentially offering a visual and qualitative indicator of subsurface water availability to trees. While this is not a substitute for physiological measurements, branch movement could support field‐based monitoring of rehydration dynamics and further new opportunities to tree water relation studies. As climate change alters snowmelt timing and moisture regimes, integrating structural and physiological indicators may enhance our understanding of plant–water interactions in cold‐region ecosystems.