Shen Huitao, Cao Jiansheng, Zhang Wanjun, Zeng Xinhua, Wang Huaru
Key Laboratory for Agricultural Water Resources, Hebei Key Laboratory for Agricultural Water-Saving, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, Hebei, China.
Yellow River Water Resources Protection Institute, Zhengzhou, He'nan, China.
PLoS One. 2014 Mar 10;9(3):e91589. doi: 10.1371/journal.pone.0091589. eCollection 2014.
Winter soil respiration is a very important component of the annual soil carbon flux in some ecosystems. We hypothesized that, with all other factors being equal, shorter winter SR result in reduced contribution to annual soil C flux. In this study, the contribution of winter soil respiration to annual soil respiration was measured for three sites (grassland: dominated by Artemisia sacrorum, Bothriochloa ischaemum and Themeda japonica; shrubland: dominated by Vitex negundo var. heterophylla; plantation: dominated by Populus tomatosa) in a mountainous area of north China. Diurnal and intra-annual soil CO2 flux patterns were consistent among different sites, with the maximum soil respiration rates at 12∶00 or 14∶00, and in July or August. The lowest respiration rates were seen in February. Mean soil respiration rates ranged from 0.26 to 0.45 µmol m(-2) s(-1) in the winter (December to February), and between 2.38 to 3.16 µmol m(-2) s(-1) during the growing season (May-September). The winter soil carbon flux was 24.6 to 42.8 g C m(-2), which contributed 4.8 to 7.1% of the annual soil carbon flux. Based on exponential functions, soil temperature explained 73.8 to 91.8% of the within year variability in soil respiration rates. The Q10 values of SR against ST at 10 cm ranged from 3.60 to 4.90 among different sites. In addition, the equation between soil respiration and soil temperature for the growing season was used to calculate the "modeled" annual soil carbon flux based on the actual measured soil temperature. The "measured" annual value was significantly higher than the "modeled" annual value. Our results suggest that winter soil respiration plays a significant role in annual soil carbon balance, and should not be neglected when soil ecosystems are assessed as either sinks or sources of atmospheric CO2.
在某些生态系统中，冬季土壤呼吸是年度土壤碳通量的一个非常重要的组成部分。我们假设，在所有其他因素相同的情况下，较短的冬季土壤呼吸导致其对年度土壤碳通量的贡献降低。在本研究中，测定了中国北方山区三个样地（草地：以铁杆蒿、白羊草和菅草为主；灌丛：以荆条为主；人工林：以毛白杨为主）冬季土壤呼吸对年度土壤呼吸的贡献。不同样地的昼夜和年内土壤CO₂通量模式一致，土壤呼吸速率最高出现在12∶00或14∶00，以及7月或8月。最低呼吸速率出现在2月。冬季（12月至2月）平均土壤呼吸速率在0.26至0.45 μmol m⁻² s⁻¹之间，生长季（5月至9月）则在2.38至3.16 μmol m⁻² s⁻¹之间。冬季土壤碳通量为24.6至42.8 g C m⁻²，占年度土壤碳通量的4.8%至7.1%。基于指数函数，土壤温度解释了年内土壤呼吸速率变化的73.8%至91.8%。不同样地10 cm深度处土壤呼吸对土壤温度的Q10值在3.60至4.90之间。此外，利用生长季土壤呼吸与土壤温度之间的方程，根据实际测量的土壤温度计算“模拟”年度土壤碳通量。“实测”年度值显著高于“模拟”年度值。我们的结果表明，冬季土壤呼吸在年度土壤碳平衡中起着重要作用，在评估土壤生态系统作为大气CO₂的汇或源时不应被忽视。
