Resprouting responses to light environment and cutting season differ across resprouting stages and leaf habit in a heavy-snow Japanese beech forest

Resprouting is a key mechanism of recovery after aboveground damage and strongly influences forest regeneration and dynamics. This is also true in heavy-snow Japanese beech forests, where canopy-gap formation and snow pressure damage woody species. Understanding how light environment and disturbance season shape resprouting is therefore essential for interpreting life-history strategies and informing forest management. To address this, we tested two hypotheses: (1) the stage-shift hypothesis, which predicts that the relative importance of ecological drivers shifts across resprouting stages, and (2) the leaf habit hypothesis, which predicts that the magnitude of seasonal effects on resprouting differs between evergreen and deciduous species. We conducted winter and spring cutting experiments on woody species in the understory of a secondary Japanese beech forest and quantified resprout initiation and growth over two years. We tested the effects of stump size, light environment, and cutting season on resprouting responses and whether seasonal effects differed between leaf habits. Resprout initiation was mainly associated with stump size, whereas light environment and cutting season had little influence. In contrast, first-year growth was enhanced by stump size and winter cutting, while second-year growth was more strongly associated with post-cutting light environment, indicating a shift in resource dependence across resprouting stages. Winter cutting had a stronger positive effect in deciduous than in evergreen species. Overall, the importance of ecological drivers changed across resprouting stages and between leaf habits, highlighting light availability and disturbance season as key determinants of resprout growth for forest management.