Suppressed water availability in winter buds delays the bud burst of broad-leaved trees in a heavy snow forest.

This article investigates how snow depth and delayed snowmelt affect budburst and leaf expansion in two canopy tree species, Quercus crispula (ring-porous) and Fagus crenata (diffuse-porous), in northeastern Japan. The study found that delayed snowmelt in forests with deep snow cover postpones budburst by suppressing water absorption rates in winter buds, a process influenced more by soil temperature than air temperature. Xylem reactivation, including current-year vessel formation and lignification, was not directly linked to the timing of budburst but was important for subsequent leaf expansion and transpiration. The findings suggest that water for bud swelling before budburst is likely supplied via previous-year vessels or nonvascular pathways, and that soil chilling from prolonged snow cover restricts water uptake in buds, thereby delaying budburst.