Relationship between frost hardiness of adults and seedlings of different tree species

Abstract

The aim of this study was to investigate the relationship between frost hardiness and the macroclimatic niche of adult individuals and seedlings of eight temperate tree species. Frost damage was investigated on winter buds and needles of adult individuals and on freshly germinated seedlings. We hypothesized that frost hardiness of adult individuals and seedlings is in accordance with their macroclimatic niche and that frost hardiness of seedlings increases with increasing plant age. Frost hardiness was tested in a climate chamber by exposing the plant material to different freezing temperatures and was assessed by LT50-values. In contrast to our expectations, we did not find any relationship between LT50-values and the macroclimatic niche variables, neither for adults nor for seedlings. There was a positive trend between seedlings development and frost hardiness, although average frost hardiness of all species differed only between -7.5 and -9 °C for one-week old and two- or four weeks old seedlings, respectively. We have to conclude that frost hardiness of adult individuals as well as seedlings at our study site does not reflect the species’ geographic distribution range, and therefore, it seems not be possible to predict the geographical distribution ranges of tree species from their frost tolerance.