Fig. 4

Hastening (brown arrow) or delaying (green arrow) phenological stages in response to drought and frost events. At the center is presented the typical seasonal phenological stages in a deciduous tree in the Northern Hemisphere and outside the potential effects of drought and frost stress depending on their timing. It should be noted that stress factors can have a lagged effect onto phenology (e.g., late drought in the late summer delaying winter dormancy release). Early and late drought typically happen in May–June and September, respectively. Early and late frost typically happen in September–October and April–May, respectively