Fig. 4
From: Trajectories in nitrogen availability during forest secondary succession: illustrated by foliar δ15N
Foliar δ15N of different forest successions in three climate regions. a Foliar δ15N at each site; b Foliar δ15N in each climate region. The box mid line, diamond, lower and upper edges, and error bar outside the boxes represent the median and mean values, the upper and lower quartiles, and the < 25th and > 75th percentiles of all data, respectively. The gray blank circle represents the distribution of foliar δ15N. The asterisks in b represent significant differences in foliar δ15N among three climate regions. Details of the site information are listed in Additional file 1: Table S1