Non-native drought-resistant species withstand winter cold and spring frost in Central Europe

Assisted migration of drought-resistant species represents an increasingly important strategy in forest management to mitigate the effects of climate change in Central Europe. However, their ecophysiology remains poorly understood, particularly regarding frost tolerance, limiting our ability to predict their establishment potential. Using a forest plantation established in 2012 at 658 m a.s.l. in Switzerland, we assessed winter frost hardiness and the risk of late spring frost in drought-resistant non-native tree species ( Fagus orientalis , Tilia tomentosa, Abies bornmuelleriana , and Cedrus libani ) and compared them with phylogenetically related native species ( Fagus sylvatica , Quercus petraea , Tilia platyphyllos , and Abies alba ). We measured lethal temperature thresholds (LT max ) for frost damage in buds and leaves, and evaluated phenological timing in relation to historical frost probability. Contrary to expectations, non-native species exhibited frost hardiness comparable to native species, with no significant differences in LT max values. As our study was conducted during the relatively mild winter of 2024–2025, the estimated frost hardiness may underestimate their full acclimation potential under colder conditions. The lack of consistent differences between native and non-native origins suggests that phenotypic plasticity and seasonal acclimation outweigh genetic differentiation. Frost probability analyses indicated a low risk of lethal frost temperatures during leaf emergence for non-native broadleaved species, while native F. sylvatica and Q. petraea were more likely to be affected by late frost. Although the two Tilia species were first to leaf out, they showed low vulnerability to late frost. Our findings suggest that frost tolerance is currently not a limiting factor for the establishment of the tested drought-resistant non-native species in Central Europe. However, their ability to acclimate to abrupt cold fronts remains unknown and may be critical for predicting susceptibility to sudden frost events. Future management practices should consider increasing phenological diversity through the use of multiple species provenances to enhance species suitability for climate-adaptive forest management. • Frost hardiness of non-native species matched native counterparts. • Bud and leaf lethal thresholds showed no consistent origin effect. • Phenology and long-term temperatures indicated low late-frost risk in non-natives. • Native beech and oak showed higher probability of late spring frost exposure. • Results support risk-informed species selection for climate-adaptive forestry.