Higher spring phenological sensitivity to forcing temperatures of Asian compared to European tree species under low and high pre-chilling conditions

Winter chilling, spring forcing temperature and photoperiod are the most important drivers explaining spatial temporal variability of phenology in temperate trees. However, how these factors interact with each other on dormancy release budburst date remains unclear varies greatly depending species. Our knowledge is also limited as to whether heat accumulation temperatures that trigger bud break a linear or non-linear process. Here, we aimed at experimentally quantifying effect forcing, their interactions dates nine different tree species from East Asia (near Beijing, China) Central Europe Zurich, Switzerland), including six phylogenetically related (same genus). We conducted full factorial experiment climate chambers using two chilling (low high, i.e., 0 vs. 56 days 2°C after sampling end December), four (5, 10, 15, 20°C), (8 16 h) treatments simultaneously Beijing Zurich. found growing near responded more readily conditions than same genus Zurich regardless treatment. Budburst timing but European beech was marginally, if all, affected by photoperiod. Furthermore, our results suggest accumulation, commonly used degree hours (GDH) model, could result accurate prediction threshold basis for accumulation. demonstrate role shaping sensitivity rate species-specific sigmoid relationship accumulating accounts prior exposure may yield better predictions dates. deciduous trees have adapted requirements regards predictability winter-spring transition late frosts. A less predictable transition, observed Europe, driven evolution towards higher compared Northeastern Asia. cross-continental therefore suggests Asian tighter coupled forests.