Fig. 3 Non-structural carbohydrate (NSC) concentrations in leaves, shoots and roots of oak (Quercus petraea ) and beech (Fagus sylvatica ) saplings after four months of drought duration treatment in 2018 (pre-winter) and before the growing season 2019 (post-winter). D0 (watering weekly), D1 (watering biweekly), D2 (watering monthly), and D3 (watering bimonthly) represent the drought duration. Different letters indicate significant differences in parameters among D0, D1, D2, and D3.