暖温带麻栎林凋落物调节土壤碳排放通量对降雨脉冲的响应

凋落物既是森林生态系统养分循环的重要构件，又是森林土壤环境和功能的关键调节因子。降雨脉冲导致的土壤碳排放变异是陆地生态系统碳汇能力评价的不确定性来源之一。凋落物在调节土壤碳排放对降雨脉冲的响应中的作用仍缺乏科学的评价。通过在暖温带栎类落叶阔叶林中设置不同凋落物处理(对照、去除凋落物和加倍凋落物)和降雨模拟实验以阐明凋落物数量变化对土壤呼吸脉冲的影响。结果表明：模拟降雨脉冲之前，不同凋落物处理下的土壤呼吸存在显著差异；与对照相比，加倍凋落物导致土壤呼吸速率显著增加57.6%,然而，去除凋落物则对土壤呼吸无显著影响。模拟降雨后52小时内，对照、去除凋落物和加倍凋落物样方的土壤累积碳排放量分别为251.69 gC/m~2,250.93 gC/m~2和409.01 gC/m~2,加倍凋落物处理下的土壤碳排放量显著高于对照和去除凋落物处理；然而，去除凋落物与对照之间无显著差异。此外，不同凋落物处理下土壤呼吸的脉冲持续时间存在显著差异；加倍凋落物显著提高降雨后土壤呼吸脉冲的持续时间，分别比对照和去除凋落物高出262%和158%。多元逐步回归分析表明，土壤总碳排放通量和土壤呼吸的脉冲持续时间与土壤理...

Litter regulates the response of soil CO2 emission to precipitation pulse in warm temperate Quercus acutissima forest

Litter is not only a critical component for nutrient cycling in forest ecosystem, but also an important regulator of soil environment and function in forests. The variation in soil CO₂ emission caused by precipitation pulse is one of the sources of uncertainty for carbon sink evaluation in the terrestrial ecosystem. The role of forest litter in regulating the response of soil CO₂ emissions to precipitation pulses remains unclear. To clarify the influence of litter quantity change on the response of soil respiration to precipitation pulse, we carried out an experiment with precipitation pulse applied on different litter treated plots (control, litter removed, and litter doubled treatments) in a Quercus acutissima forest in the warm temperate zone (Jigong Mountain at Henan Province). The results showed that there were significant differences in soil respiration between plots with different litter treatments before the application of precipitation pulse. Specifically, compared with the control, litter doubled treatment significantly increased soil respiration rate by 57.6%, however, litter removed treatment showed no significant effect on soil respiration. Within 52 hours after the application of precipitation pulse, the cumulative soil CO₂ emissions were 251.69 gC/m², 250.93 gC/m², and 409.01 gC/m² under control, litter removed, and litter doubled treatments, respectively. In addition, soil CO₂ emissions under litter doubled treatment were significantly higher than those in both control and litter removed treatment; however, there was no significant difference between litter removed treatment and the control. Moreover, substantial differences in the duration time of soil respiration after precipitation pulse were found between plots with different litter treatments. Litter doubled treatment substantially elevated the duration time of soil respiration after precipitation pulse, showing 262% and 158% higher than the control and litter removed treatment, respectively. Multiple stepwise regression analysis indicated that cumulative soil CO₂ emissions and the duration time of soil respiration were closely related to the soil physicochemical properties. Soil microbial biomass nitrogen alone was responsible for 30.3% variations in cumulative soil CO₂ emission, while soil nitrate nitrogen content and soil organic carbon content together accounted for 69.5% variations in the duration time of soil respiration after the precipitation pulse. The findings in this study suggest that the forest litter quantity and its interception effect on rainfall play an important role in regulating soil CO₂ emission. Therefore, the potential indirect effect of forest litter on soil microclimate should be taken into account while assessing the effects of litter on carbon cycling processes in forest ecosystems.