Response mechanism of anthocyanins accumulation in young leaves of dominant tree species in different successional stages of subtropical forests to environmental temperature changes

Red young leaves represent a common phenomenon among tropical and subtropical forest tree species. This study examined the seasonal patterns of leaf reddening and the mechanisms underlying temperature-mediated anthocyanin accumulation in young leaves of tree species at different successional stages in the Dinghushan forest. Nineteen mid-successional and 34 late-successional tree species in Dinghushan forest were selected to investigate young leaf coloration and physiological parameters in summer and winter under field conditions. Two mid-successional and two late-successional dominant tree species were selected for pot experiment to examine the response of young leaf coloration and physiological parameters to seasonal temperature variation. In Dinghushan forest, more than half of mid- and late-successional tree species accumulated anthocyanins in young leaves year-round, whereas approximately 40% of late-successional species accumulated anthocyanins exclusively in winter. In the pot experiment, young leaves of mid-successional dominant species accumulated anthocyanins under high summer temperature, whereas those of late-successional dominant species accumulated anthocyanins under low winter temperature. Anthocyanins' accumulation was positively correlated with soluble sugars in both field and pot experiment. Furthermore, anthocyanins' accumulation did not significantly influence antioxidant capacity. The results revealed distinct seasonal patterns of leaf reddening in young leaves of tree species at different successional stages in subtropical forests. Leaf reddening appears to be regulated by temperature and induced by soluble sugars. Furthermore, red coloration provides photoprotection for young leaves. These findings enhance our understanding of successional dynamics in subtropical forests.