A Negative Relationship between Foliar Carbon Isotope Composition and Mass-Based Nitrogen Concentration on the Eastern Slope of Mount Gongga, China

Plants adopt ecological strategy to resist environmental changes and increase their resource-use efficiency. The ecological strategy includes changes in physiological traits and leaf morphology, which may result in simultaneous variations in foliar N concentration and the ratio of intercellular CO(2) concentration to ambient CO(2) concentration (c(i)/c(a)). This in turn links to foliar carbon isotope discrimination, and thus, a relationship between foliar N concentration and foliar carbon isotope composition (δ(13)C) is expected. To understand how plants integrate their structural and physiological resistance to environmental changes, the relationship between foliar N concentration and foliarδ(13)C has been assessed intensively, especially the correlation between area-based N concentration (N(area)) and δ(13)C.Less effort has been dedicated to the examination of the relationship between mass-based N concentration(N(mass)) and δ(13)C. Studies on the N(mass)–δ(13)C relationship, especially those including a large amount of data and species, will enhance our understanding of leaf economics and benefit ecological modeling. The present study includes an intensive investigation into this relationship by measuring foliar N(mass) and δ(13)C in a large number of plant species grown on the eastern slope of Mount Gongga, China. This study shows that foliar N(mass) decreases with increasing δ(13)C, which is independent of functional group, vegetation type, and altitude. This suggests that a negative correlation between N(mass) and δ(13)C may be a general pattern for plants grown not only on Mount Gongga, but also in other areas.