Fig. 3From: Nitrogen uptake strategies of mature conifers in Northeastern China, illustrated by the 15N natural abundance methodδ15N values of foliage and of soil DON, NH4+, and NO3− in 0–20 cm mineral soil (means ± SE, n = 5) in the four forest plantations. Different letters on bar of the same color indicate significant differences among four forest plantations in their δ15N values (one-way ANOVA, P < 0.05)Back to article page