中文关键词
土壤微生物呼吸土壤微生物呼吸温度敏感性土壤水分土壤温度黄土高原 | 英文关键词soil microbial respiration ratetemperature sensitivity of soil microbial respirationsoil moisturesoil temperatureLoess Plateau |
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| 中文摘要 |
| 在田间条件下研究土壤微生物呼吸及其温度敏感性（Q10）的变化特征及其影响因素对准确理解地区的气候变暖潜力具有重要意义.本研究依托长武农田生态试验站的裸地处理，利用土壤碳通量系统（Li~8100）连续6 a（2008~2013年）监测裸地处理下的呼吸速率、土壤温度和水分，探究土壤微生物呼吸及其温度敏感性的变化特征及其影响因素.在日变化尺度上，土壤微生物呼吸速率的变化特征呈单峰曲线，且这种变化趋势主要与土壤温度有关（P<0.05），然而日平均土壤微生物呼吸速率和Q10在不同土壤水分含量条件下不同.均呈现出：适度的土壤水分条件 > 较高的土壤水分条件 > 较低土壤水分条件的趋势［土壤微生物呼吸速率：1.20 μmol·（m2·s）-1、0.95 μmol·（m2·s）-1、0.79 μmol·（m2·s）-1；Q10：2.12、1.93、1.59］.在季节尺度上，土壤微生物呼吸速率和Q10均呈现出雨季大于非雨季的趋势［土壤微生物呼吸速率：1.11 μmol·（m2·s）-1、0.90 μmol·（m2·s）-1；Q10：1.96、1.59］，且这种变化趋势与土壤温度和水分的变化有关（P<0.05），然而土壤温度和土壤水分的双变量模型比土壤温度或者土壤水分的单变量模型能解释更多的土壤微生物呼吸季节变异性（R2：0.45~0.82、0.32~0.67、0.35~0.86；模拟值和实测值的拟合系数：0.76、0.64、0.58）.在年际尺度上，年累积土壤微生物呼吸变化于226 g·（m2·a）-1和298 g·（m2·a）-1之间，Q10变化于1.48~1.94之间，而年累积土壤微生物呼吸和Q10的年际变异性主要与年平均土壤水分含量有关（P<0.05），且年平均土壤水分别可以解释39%和54%的年累积土壤微生物呼吸和Q10年际变异性.在裸地处理上，土壤有机碳由试验初的6.5 g·kg-1下降到目前的5.5 g·kg-1，但是年累积土壤微生物呼吸却高达255 g·（m2·a）-1，即裸地处理的呼吸流失量比土壤有机碳的流失量高20倍以上. |
| 英文摘要 |
| Studying the effect of environmental factors on the variation of soil microbial respiration and its temperature sensitivity (Q10) at different time scales under field conditions is of great significance for accurately understanding the region's climate warming potential. From March 2008 to November 2013, in situ soil microbial respiration rates were determined using an automated CO2 flux system (Li~8100) in long-term bare fallow soil at the Changwu State Key Agro-Ecosystem Experimental Station, Shaanxi, China, for studying the effect of environmental factors on the variation of soil microbial respiration and Q10 at different time scales. At diurnal time scales, the daily variation of soil microbial respiration rates showed a single-peak curve, which was closely related to soil temperature (P<0.05); whereas the daily mean soil microbial respiration rate and Q10 varied with soil moisture, with both showing the order of moderate soil moisture conditions > higher soil moisture conditions > lower soil moisture conditions[daily mean soil microbial respiration rate:1.20 μmol·(m2·s)-1 vs. 0.95 μmol·(m2·s)-1 vs. 0.79 μmol·(m2·s)-1; Q10:2.12 vs. 1.93 vs. 1.59]. At seasonal time scales, both the seasonal mean soil microbial respiration rate and Q10 showed the order of rainy season > non-rainy season[seasonal mean soil microbial respiration rate:1.11 μmol·(m2·s)-1vs. 0.90 μmol·(m2·s)-1; Q10:1.96 vs. 1.59], which was consistent with the trend of soil temperature and moisture (soil temperature:20.39 vs. 14.50℃; soil moisture:49.2% vs. 38.6%). The bivariate model of soil temperature and soil moisture could explain the greater seasonal variability of the soil microbial respiration rate than did the univariate model of soil temperature or soil moisture (R2:0.45-0.82 vs. 0.32-0.67 vs. 0.35-0.86; the fitting coefficient between the simulated and measured soil microbial respiration rates:0.76 vs. 0.64 vs. 0.58). At annual time scales, the annual cumulative soil microbial respiration ranged from 226 to 298 g·(m2·a)-1, with an average of 253 g·(m2·a)-1, and the annual Q10 ranged from 1.48 to 1.94, with an average of 1.70. The annual cumulative soil microbial respiration and Q10 showed a negative quadratic correlation with annual mean soil moisture (P<0.05), with the annual mean soil moisture explaining 39% and 54% of the annual variability of annual cumulative soil microbial respiration and Q10, respectively. In the bare soil treatment, the soil organic carbon decreased from 6.5 g·kg-1 at the beginning of the experiment to 5.5 g·kg-1 at present; whereas, the annual cumulative soil microbial respiration was up to 255 g·(m2·a)-1 and the loss of annual cumulative soil microbial respiration was 20 times larger than the loss of soil organic carbon in the Loess Plateau region, China. |
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