Nitrogen stable isotope composition of leaves and roots of plants growing in a forest and a meadow
In controlled N-nutrition experiments, differences in δ 15N composition of leaves and roots are regularly found. In this paper we report results from a survey of nitrogen stable isotope signatures of leaves and roots of 16 plant species growing under natural conditions in a meadow and a forest understorey, which differed in nitrate and ammonium availability. Significant differences between leaf and root were observed. The range of Δ 15N [leaf-root] values was m 0.97 to +0.86, small compared to published values from controlled N-nutrition experiments, but almost as large as the range of leaf δ 15N values (m 1.04 to +1.08). Forbs showed the largest differences between leaves and roots and showed a significant difference with respect to habitat. Grasses and legumes did not show significant differences in Δ 15N [leaf-root] between the two habitats. Care must be taken when using leaf δ 15N values as representative for whole-plant 15N composition in these two habitats.