δ¹³C values of leaves, leaf litter, and semi-decomposed litter in the natural secondary broadleaf stands at altitudes of 219, 405, 780, and 1268 m in the Lushan Mountain.

<p>The error bars are the standard errors (n = 3 for leaf litter and semi-decomposed litter, and n = 3 for 300 leaves). Different letters indicate significant differences among all classes at the different altitudes (<i>P</i><0.05).