We have started a new project collaboration with our colleagues from Ticino and Basel, where we compare the frost tolerance and photosynthetic performance of native and evergreen trees and palms from winter to summer. For this, we travelled to a forest site near Ascona (TI) and sampled leaves of co-occurring evergreens such as the local common holly, the invasive Chinese windmill palm and laurel. The leaves then travelled to the Botanical Institute in Basel where they were frozen at temperatures from -4 ºC to -34 ºC before Alex brought them back to our lab to be measured.
We expect that the invasive evergreens are more active in terms of photosynthesis during winter, compared to the natives, which allows them to outcompete the native vegetation. On the other hand, we also expect the non-natives to be less resistant to frost temperatures, which in the past might have limited their spread. As we have less and less cold winters in recent years, the lower frost resistance may not really pose a problem for the invasives anymore, so we might end up seeing more of them in the future.