Relationship between mean annual precipitation and soil organic carbon (SOC), soil total nitrogen (STN) stock, and C:N ratio in cropland and younger and older plantations.

<p>Younger and older plantations are 5- to 9-year-old and 25- to 30-year-old forests, respectively. The error bars represent the standard deviations of the means (only shown in positive, n = three to six for each stand). The data for some cropland stands were cited from other studies (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0085426#pone-0085426-t001" target="_blank">Table 1</a>). Regressions were conducted for the top 20 cm of soil, and only significant regression models are displayed.