Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Assisted migration, the human-mediated movement of species and populations, is one adaptive strategy to climate change. Plant phenology affects the survival and distribution of species under local conditions, and its potential modifications need to be explored in the context of assisted migration. We conducted identical experiments in January and April (experiment I and II) and monitored the timing of bud break in sugar maple (Acer saccharum Marshall) under cooling and longer photoperiod to simulate a northward migration. The bud break in experiment II started 55 days earlier than experiment I. In experiment I, a longer photoperiod was more effective than warming in advancing bud break. Compared with experiment II, cooling and long photoperiod had stronger effect in experiment I. Our results demonstrated the significant effect of chilling and confirmed that photoperiod outweighs temperature in initiating bud break when the chilling requirement is unfulfilled. These findings suggest that the future mild winters in the southern range of sugar maple may reduce chilling accumulation and result in the delayed bud break. Sugar maples migrating northward could benefit from longer day lengths, which could partly counteract the delayed effects of colder springs in northern regions, thus ensuring a sufficient growth period.