This book provides an overview of how boreal andtemperate tree species have adapted their annual development cycle to theseasonally varying climatic conditions. Therefore, the frost hardy dormant phase, and thesusceptible growth phase, are synchronized with the seasonality of the climate. The volume discusses the annual cycle, including variousattributes such as timing of bud burst and other phenological events, seasonalityof photosynthetic capacity or the frost hardiness of the trees. During the last few decades dynamic ecophysiologicalmodels have been used increasingly in studies of the annual cycle, particularlywhen projecting the ecological effects of climate change. The main emphasis of this volume is oncombining modelling with experimental studies, and on the importance of thebiological realism of the models.