3.2 Pre-winter NSC after drought duration treatment
The pre-winter NSC levels in leaves differed significantly with species
(Table 2). The shoot NSC levels, however, did not vary with species but
were significantly affected by both drought treatment and
N-fertilization (Table 2). The root NSC was significantly influenced by
species and drought duration (Table 2). In addition, N-fertilization
significantly interacted with species to affect the NSC levels in both
shoots and roots (Table 2). Compared to the D0, D1 and D2 treatments,
oaks in D3 had significantly higher leaf NSC levels (Fig. 3a), mainly
caused by higher sugar concentration (Fig. S4a), but significantly lower
shoot NSC (Fig. 3b) mainly resulting from significantly lower starch
levels (Fig. S4e). The root NSC of oak tended to decrease with
increasing drought duration (Fig. 3c), due to both decreasing sugar and
starch levels (Fig. S4c,f). For beech, both leaf and root NSC levels did
not change with drought (Fig. 3f,h) but shoot NSC decreased with
increasing drought duration (Fig. 3g) caused by both decreased sugars
(Fig. S5b) and starch (Fig. S5l). N-fertilization significantly
increased the shoot NSC in oak (Fig. 3b), whereas it significantly
decreased NSC levels in shoots (Fig. 3g) and roots (Fig. 3h) of beech.