PS 29-158 - Divergent patterns of δ13C versus δ15N in Quercus aquifolioides along an altitudinal gradient: An integrated study based on multiple foliar traits

Tuesday, August 9, 2011
Exhibit Hall 3, Austin Convention Center
Chen Litong Sr., Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
  1. Due to the different mechanisms underlying δ13C and δ15N, we hypothesized that they could exhibit differing patterns across an environmental gradient, particularly an elevation gradient.
  2. In this study, we investigated the shifting patterns of both δ13C and δ15N of Quercus aquifolioides in the Tibetan Plateau with altitudes from 2500 to 3800 m based on measures of multiple foliar traits.


  1. Foliar δ13C significantly increased linearly toward increasing altitude. By contrast, foliar δ15N initially increased with the altitudinal gradient, but subsequently decreased around 3300 m. Principal components analysis (PCA) showed that the first principal component (PC1) associated with the δ13C, LMA, LM, LT, LA, Cmass, Carea, SD, SL and St/LM accounted for 45.78% of total variance of leaf traits and represented an axis of water availability, and the second principal component (PC2) related to the δ15N, Nmass, Narea, C: N, St/N accounted for 26.57% of total variance and represented an axis of N availability across the entire elevation gradient.
  2. Further analyses showed that (1) δ13C showed significantly positive correlations with LMA, LM and LT, and negative correlations with stomatal parameters (SD, SL and St/LM), but no correlation with Nmass and Narea; and (2) δ15N is positively correlated with Nmass and Narea whereas negatively correlated with C: N and St/N. These suggest that leaf conductance, rather than photosynthetic capacity, could result in altitudinal variations of foliar δ13C while altitudinal variations of the δ15N may be closely correlated with leaf N concentrations and N availability.
  3. We therefore concluded that the foliar δ13C with LMA, LM, LT, SD, SL and St/LM could reflect water use strategy, while foliar δ15N with leaf Nmass, Narea and C: N could be related to nutrient use strategy, particularly N availability in the studied species along the altitudinal gradient in the Tibetan Plateau.

Abbreviations: δ13C, ratio of 13C to 12C; δ15N, ratio of 15N to 14N; LMA, leaf mass per unit area; Nmass and Narea, leaf N concentration per unit mass and area; Cmass and Carea, leaf C concentration per unit mass and area; C: N, ratio of leaf N concentration to leaf C concentration; SD, stomatal density; SL, the length of stomata; St/N and St/LM, number of stomata per gram of leaf nitrogen and mass; LA, leaf area; LM, leaf mass; LT, leaf thickness.

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