Fig. 1

N, P, and K concentration (mean ± SE) in shoots (a, c, e) or roots (b, d, f) of Holm oak (Q. ilex) as affected by fall fertilization: no fertilization (control), fertilizer rate (28 versus 56 mg of N), and timing (early versus late fall, EF and LF, respectively) at two sampling periods (intermediate and final). Level 28 mg of N also included 12.2 and 23.4 mg of P and K, respectively, and double amount for level 56 mg N. Asterisks on control bars indicate significance of the contrast that compares control mean with the average of all the other treatment means. Within a factor level (fertilizer rate or timing) and sampling period (intermediate or final), when no letters are given next to the bars, no significant treatment effect was apparent from the factorial ANOVA treatment (capital letters for comparison among intermediate sampling treatments). For root N concentrations, two-way interactive effect is presented (see Table 1), precluding main effects comparisons. For this plant component, the same letters within a sampling period reflect no significant N differences among treatments according to Fisher LSD post hoc test. See Table 1 for sample size