During litter decomposition, three major fates of litter carbon (C) are possible: emission as carbon dioxide (CO 2 ) into the atmosphere, leaching of dissolved organic carbon (DOC), and translocation and transformation into soil organic carbon (SOC). Soil moisture, one of the key drivers of litter decomposition, is predicted to change in the future due to shifts in precipitation patterns. We explored the effects of low, medium and high rainfall intensities on the partitioning of litter carbon fates in a 6-month long laboratory experiment. We tracked carbon in 13 C-labeled tulip poplar litter in a laboratory mesocosms by measuring respiration rates, dissolved organic carbon in the leachate, and soil organic carbon at the end of the experiment. Mesocosms with the same three rainfall intensities but without leaf litter were also set up. Leaching of labile carbon caused priming, but the effect was stronger in the low intensity treatment. Transport of litter-derived carbon also differed: in high intensity treatment there was more total carbon in the surface soil and more litter-derived carbon in in the deep soil layers. The cumulative CO 2 efflux was not significantly different. Our results highlight that extreme rainfall events, as projected by most climate models, may lead to altered carbon cycling in temperate forest soils.

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不同降雨模式下分解过程中凋落物碳命运的分配：一项实验室研究

在凋落物分解过程中，凋落物碳 (C) 的三种主要命运是可能的：作为二氧化碳 (CO 2 ) 排放到大气中，溶解有机碳 (DOC) 的浸出，以及易位和转化为土壤有机碳 (SOC)。土壤水分是凋落物分解的主要驱动因素之一，预计未来会因降水模式的变化而发生变化。我们在为期 6 个月的实验室实验中探讨了低、中和高降雨强度对凋落物碳命运分配的影响。在实验结束时，我们通过测量呼吸速率、渗滤液中溶解的有机碳和土壤有机碳，在实验室中层环境中追踪了 13 C 标记的郁金香杨凋落物中的碳。还建立了具有相同三种降雨强度但没有落叶的中世界。不稳定碳的浸出引起引发，但在低强度处理中效果更强。凋落物衍生碳的传输也不同：在高强度处理中，表层土壤中的总碳含量更高，而深层土壤中的凋落物衍生碳含量更高。累积的CO 2 流出量没有显着差异。我们的结果强调，正如大多数气候模型所预测的那样，极端降雨事件可能会导致温带森林土壤中碳循环的改变。