Warming Drives Large‐Scale Shifts in Post‐Disturbance Vegetation Dynamics and Expansion of Deciduous Trees in the Boreal Forest in a Dynamic Vegetation Model

The intensification of disturbance regimes due to climate change is a growing concern in boreal forests, yet the long‐term consequences for forest recovery remain poorly understood, as boreal successional dynamics unfold over a century or longer and exceed the length of available observational records. To overcome this research gap we use the dynamic vegetation model LPJ‐GUESS to investigate future climate change impacts on boreal successional dynamics over the 21st and 22nd centuries. We first confirm that LPJ‐GUESS reproduces historic patterns of post‐disturbance recovery. We then show that under future warming, deciduous transients become more frequent, longer, and more pronounced due to a temperature‐mediated shift in competitive balance emerging in LPJ‐GUESS. Using a random forest framework, we find that the long‐term recovery pathway can be predicted with 90% accuracy from vegetation and environmental conditions in the first decade after disturbance alone. This supports the hypothesis that the changes in post‐disturbance recruitment currently observed in boreal forests are an indicator of more long‐lasting changes in vegetation composition in the future. While we find no evidence for permanent shifts toward deciduous tree cover in LPJ‐GUESS, the combination of prolonged deciduous transients and more frequent disturbances makes an increase in deciduous tree cover a likely future scenario.