Unravelling resilience mechanisms in forests: role of non-structural carbohydrates in responding to extreme weather events

Summary Extreme weather events are increasing in frequency and intensity due to global climate change. We hypothesized that these have a strong impact on the stem radial growth and the dynamic of non-structural carbohydrates (NSCs). In order to assess the effects on mature trees of a late frost occurred in spring 2016 and a drought event characterizing the summer 2017, we monitored the phenology, the radial growth and the dynamic of starch and soluble sugars in a Mediterranean beech forest. Growth was much more reduced by spring late frost than by summer drought, while NSCs dynamic was deeply involved in counteracting the negative effects of both events, supporting plant survival and buffering source-sink imbalances under such stressful conditions, resulting in a strong trade-off between growth and NSCs dynamic in trees. Overall, our results highlight the key role of NSCs on trees resilience to extreme weather events, confirming the relevant adaptability to stressful conditions. Such an insight is useful to assess how forests may respond to the potential impacts of climate change on ecosystem processes and to define how future management strategies can help adaptation of beech forests in the Mediterranean area.