3.4 Changes in NSC level over winter
Only N-fertilization significantly affected the over-winter NSC consumption (post-winter level minus pre-winter level) in shoots but not in roots (Table S1). Neither D nor N and their interactions changed the tissue NSC consumption in oak over-winter (Fig. 4a,c), while N-fertilized beech significantly decreased the over-winter NSC consumption in both shoots and roots (Fig. 4b,d). The changes in sugar/starch ratio were significantly influenced by both, species and N-fertilization (Table S1). N-fertilization tended to decrease the sugar/starch ratio in beech, especially in shoots of D3 plants (Fig. 4f,h), while the unfertilized oak saplings seemed to increase the tissue sugar/starch ratio over winter, especially the D3 plants (Fig. 4e,g).