Frost stress is one of the most important limiting factors in the ecological distribution and production of tree species, especially at high elevation and latitude. Assessment of frost risk is therefore critical for forestry, fruit production, and horticulture. Frost risk is substantial when the hazard (i.e. exposure to damaging freezing temperatures) exceeds the vulnerability (i.e. frost sensitivity). Frost affects both living cells and dead xylem elements and alters their hydraulic function by inducing embolism. The authors developed methods (LT50, ultrasonic acoustic emission and high resolution dendrometer measurements) to better the effect of frost in different tree species and growth forms and its relevance to plant life at high elevation but also to improve knowledge on frost tolerance and plant resilience in general.