| Summary: | Understanding the impacts of nitrogen (N) addition on soil respiration (<i>R</i><sub>S</sub>) and its temperature sensitivity (<i>Q</i><sub>10</sub>) in tropical forests is very important for the global carbon cycle in a changing environment. Here, we investigated how <i>R</i><sub>S</sub> respond to N addition in a tropical montane rainforest in Southern China. Four levels of N treatments (0, 25, 50, and 100 kg N ha<sup>−1</sup> a<sup>−1</sup> as control (CK), low N (N25), moderate N (N50), and high N (N100), respectively) were established in September 2010. Based on a static chamber-gas chromatography method, <i>R</i><sub>S</sub> was measured from January 2015 to December 2018. <i>R</i><sub>S</sub> exhibited significant seasonal variability, with low <i>R</i><sub>S</sub> rates appeared in the dry season and high rates appeared in the wet season regardless of treatment. <i>R</i><sub>S</sub> was significantly related to the measured soil temperature and moisture. Our results showed that soil <i>R</i><sub>S</sub> increased after N additions, the mean annual <i>R</i><sub>S</sub> was 7% higher in N25 plots, 8% higher in N50 plots, and 11% higher in N100 plots than that in the CK plots. However, the overall impacts of N additions on <i>R</i><sub>S</sub> were statistically insignificant. For the entire study period, the CK, N25, N50, and N100 treatments yielded <i>Q</i><sub>10</sub> values of 2.27, 3.45, 4.11, and 2.94, respectively. N addition increased the temperature sensitivity (<i>Q</i><sub>10</sub>) of <i>R</i><sub>S</sub>. Our results suggest that increasing atmospheric N deposition may have a large impact on the stimulation of soil CO<sub>2</sub> emissions from tropical rainforests in China.
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