Correlation between leaf δ¹³C and leaf N_mass for different plant groups.

<p>Correlation between leaf δ¹³C and leaf N_mass for different plant groups.</p

Results of reduced major axis regressions of N_mass vs. δ¹³C for different plant groups.

<p>Results of reduced major axis regressions of N_mass vs. δ¹³C for different plant groups.</p

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

<div><p>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 CO₂ concentration to ambient CO₂ 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 (δ¹³C) is expected. To understand how plants integrate their structural and physiological resistance to environmental changes, the relationship between foliar N concentration and foliarδ¹³C has been assessed intensively, especially the correlation between area-based N concentration (N_area) and δ¹³C.Less effort has been dedicated to the examination of the relationship between mass-based N concentration(N_mass) and δ¹³C. Studies on the N_mass–δ¹³C 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 δ¹³C 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 δ¹³C, which is independent of functional group, vegetation type, and altitude. This suggests that a negative correlation between N_mass and δ¹³C may be a general pattern for plants grown not only on Mount Gongga, but also in other areas.</p></div

Correlation between leaf δ¹³C and leaf N_mass for different vegetation types.

<p>a: evergreen broad-leaved forests; b:coniferous and broad-leaved mixed forests; c:frigid dark coniferous forests; d:alpine sub-frigid shrub and meadow vegetation; and e:alpine frigid meadow vegetation. Solid lines indicate the linear regressions of δ¹³C vs. N_mass.</p

Comparison of the results of bivariate correlation analysis and partial correlation analyses of N_mass vs.δ¹³C after controlling for functional group, vegetation type, and altitude.

<p>Comparison of the results of bivariate correlation analysis and partial correlation analyses of N_mass vs.δ¹³C after controlling for functional group, vegetation type, and altitude.</p

Results of reduced major axis regressions of N_mass vs.δ¹³C for different vegetation types.

<p>Results of reduced major axis regressions of N_mass vs.δ¹³C for different vegetation types.</p

Variations in leaf δ¹³C with altitude for different functional groups.

<p>a: seed plants; b: herbaceous plants; c:woody plants; d: ferns; e:annual herbaceous plants; f:perennial herbaceous plants; g:evergreen woody plants; h: deciduous woody plants.</p

What’s the Key Factor to Ensure the Photoactivity Enhancement of Fe₂O₃ Films with Ni(OH)₂ Loading: Clues from a Structural Modification with Flagella Nanowires

A much higher photoactivity enhancement of Fe₂O₃ photoanode films was achieved by loading flagella-nanowire-modified Ni­(OH)₂ than by loading pure Ni­(OH)₂. Cyclic voltammetry curves and coupled <i>i</i>–<i>t</i>/potential step chronoamperometry measurements under super band gap irradiation revealed a much heavier hole accumulation in a pure Ni­(OH)₂ layer. Electrochemical impedance and coupled <i>i</i>–<i>t</i>/open circuit potential transient measurements were applied to explore the dynamics of hole transfer through the Fe₂O₃|Ni­(OH)₂|electrolyte multiple interface systems, finding that the structural modification of Ni­(OH)₂ with flagella nanowires can speed up the charge transfer at both the Fe₂O₃|Ni­(OH)₂ and Ni­(OH)₂|electrolyte interfaces. Based on a recent discovery that the ion-permeable Ni­(OH)₂ electrocatalyst acts as a surface-attached redox system, a theoretical model was proposed to explain the influence of hole accumulation in Ni­(OH)₂ layer on the photoactivity of Fe₂O₃ films. The outcome of this work implies that the key factor guaranteeing the enhancement effect is that hole transfer rate at the Ni­(OH)₂|electrolyte interface should be higher than that at the Fe₂O₃|Ni­(OH)₂ interface