Effect of wetting intensity on soil GHG fluxes and microbial biomass under a temperate forest floor during dry season
Effect of wetting intensity on soil GHG fluxes and microbial biomass under a temperate forest floor during dry season
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DOI：
10.1016/j.geoderma.2011.11.016
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发表时间：
2012-01
期刊：
影响因子：
6.1
通讯作者：
Xingkai Xu;Xianbao Luo
中科院分区：
文献类型：
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作者：
Xingkai Xu;Xianbao Luo
预计本世纪周期性干旱和强降雨的频率将会增加，但人们对湿润强度对森林土壤和土壤微生物生物量原位生物温室气体（GHG）通量的影响知之甚少。为了获得对原位湿润引起的温室气体通量的潜在机制的新见解，在中国东北部的温带森林下进行了自然长期干旱期间的降雨模拟田间实验。降雨引起的 CO2 脉冲强度从 0.84 g CO2–Cm−2d−1 增加到 2.08g CO2–Cm−2d−1，润湿强度达到约 2.08 g CO2–Cm−2d−1。 80% 的孔隙空间充满水，这与土壤微生物生物量的增加和润湿后土壤不稳定有机碳的减少相一致。随着润湿强度的增加，甲烷吸收率从 1.76 mg CH4–Cm−2d−1 下降到 0.87mg CH4–Cm−2d−1。湿润干燥的森林地面使 N2O 通量从 6.2 增加到 25.9μg N2O–Nm−2d−1，但所有实验湿润地块之间没有显着差异。随着润湿强度的增加，降雨引起的 N2O 脉冲与 CO2 脉冲相反，在最低润湿强度下显示出最大响应。温室气体通量的温度敏感性分析表明，在潮湿和干燥条件下，温度分别对原位 CO2 通量和 CH4 吸收的影响增加。 GHG通量的全球变暖潜势和CO2通量温度响应的Q10值随润湿强度线性增加。结果表明，降雨引起的土壤二氧化碳脉冲主要是由于微生物对基质的消耗增加，并突显了中国东北森林地下碳循环对气候变化响应的复杂性，这些森林通常会经历周期性干旱，然后是全年强降雨。
The increasing frequency of periodic droughts followed by heavy rainfalls is expected for this current century, but little is known about the effects of wetting intensity on the in situ biogenic greenhouse gas (GHG) fluxes of forest soils and soil microbial biomass. To gain new insights into the underlying mechanisms responsible for wetting-induced GHG fluxes in situ, rain simulation field experiments during a natural prolonged drought period were done under a temperate forest in northeast China. The intensity of rainfall-induced CO2pulses increased from 0.84 to 2.08g CO2–Cm−2d−1with the intensity of wetting up to ca. 80% water-filled pore space, which coincided with an increase in soil microbial biomass and with a decrease in soil labile organic C following wetting. Methane uptake rates decreased from 1.76 to 0.87mg CH4–Cm−2d−1with the intensity of wetting. Wetting dry forest floor increased N2O fluxes from 6.2 to 25.9μg N2O–Nm−2d−1, but there was no significant difference between all experimental wetted plots. The rainfall-induced N2O pulses with increasing wetting intensity were opposite to that of the CO2pulses, showing a maximum response at the lowest wetting intensity. An analysis of the temperature sensitivity of GHG fluxes indicated that temperature had an increased effect on the in situ CO2flux and CH4uptake, respectively, under wetted and dry conditions. The global warming potential of GHG fluxes and Q10value of the temperature response of CO2fluxes increased linearly with wetting intensity. The results indicate that the rainfall-induced soil CO2pulse is mainly due to enhanced microbial consumption on substrates and highlight the complex nature of belowground C-cycling responses to climate change in northeast China forests that normally experience periodic droughts followed by heavy rainfalls over the year.