Graduate University of Chinese Academy of Sciences, Beijing, China.
PLoS One. 2013;8(1):e53761. doi: 10.1371/journal.pone.0053761. Epub 2013 Jan 14.
Improved understanding of changes in soil recalcitrant organic carbon (C) in response to global warming is critical for predicting changes in soil organic C (SOC) storage. Here, we took advantage of a long-term field experiment with increased temperature and precipitation to investigate the effects of warming, increased precipitation and their interactions on SOC fraction in a semiarid Inner Mongolian grassland of northern China since April 2005. We quantified labile SOC, recalcitrant SOC and stable SOC at 0-10 and 10-20 cm depths. Results showed that neither warming nor increased precipitation affected total SOC and stable SOC at either depth. Increased precipitation significantly increased labile SOC at the 0-10 cm depth. Warming decreased labile SOC (P = 0.038) and marginally but significantly increased recalcitrant SOC at the 10-20 cm depth (P = 0.082). In addition, there were significant interactive effects of warming and increased precipitation on labile SOC and recalcitrant SOC at the 0-10 cm depth (both P<0.05), indicating that that results from single factor experiments should be treated with caution because of multi-factor interactions. Given that the absolute increase of SOC in the recalcitrant SOC pool was much greater than the decrease in labile SOC, and that the mean residence time of recalcitrant SOC is much greater, our results suggest that soil C storage at 10-20 cm depth may increase with increasing temperature in this semiarid grassland.
提高对土壤抗分解有机碳（C）在全球变暖下变化的理解，对于预测土壤有机碳（SOC）储量的变化至关重要。在这里，我们利用一个长期的增温和增加降水的野外实验，自 2005 年 4 月以来，调查了变暖、增加降水及其相互作用对中国北方半干旱内蒙古草原土壤中 SOC 各组分的影响。我们在 0-10 和 10-20 cm 深度量化了易分解 SOC、抗分解 SOC 和稳定 SOC。结果表明，变暖或增加降水都没有影响到任何深度的总 SOC 和稳定 SOC。增加降水显著增加了 0-10 cm 深度的易分解 SOC。变暖（P = 0.038）减少了 10-20 cm 深度的易分解 SOC，且略有但显著增加了抗分解 SOC（P = 0.082）。此外，变暖和增加降水对 0-10 cm 深度的易分解 SOC 和抗分解 SOC 有显著的交互作用（均 P<0.05），这表明由于多因素相互作用，单一因素实验的结果应该谨慎对待。鉴于抗分解 SOC 库中 SOC 的绝对增加量远大于易分解 SOC 的减少量，而且抗分解 SOC 的平均停留时间要长得多，因此，我们的研究结果表明，在这个半干旱草原中，土壤 C 储量在 10-20 cm 深度可能会随着温度的升高而增加。
