Differences between four sympatric subtropical tree species in the interactive effects of three environmental cues on leaf-out phenology

•How environmental cues interactively regulate spring phenology remains largely unstudied.•A novel method to test vegis theory, interaction of chilling and forcing, was introduced.•Vegis effect was found in two species, while effects of photoperiod were generally minor.•In the other species, the timing of leaf-out was mainly regulated by forcing.•This implies that species-specific models are needed in global change research.