Fig. 4 Over-winter changes in non-structural carbohydrate (NSC) concentrations (post-winter values minus pre-winter values) and the sugar/starch ratio in shoots and roots of oak (Quercus petraea ) and beech (Fagus sylvatica ) saplings treated with four drought durations during the previous growing season. D0 (watering weekly), D1 (watering biweekly), D2 (watering monthly), and D3 (watering bimonthly) represent the drought duration.