Fig. 5 Leaf net-photosynthesis (Aleaf) and relative height increment of oak (Quercus petraea ) and beech (Fagus sylvatica ) saplings treated with four drought durations in 2018 and well-watered in 2019. D0 (watering weekly), D1 (watering biweekly), D2 (watering monthly), and D3 (watering bimonthly) represent the drought duration. Different letters indicate significant difference in parameters among D0, D1, D2, and D3.