Changing precipitation patterns and global warming have greatly changed winter snow cover, which can affect litter decomposition process by altering soil microenvironment or microbial biomass and activity. However, it remains unknown how and to what extent snow cover affects litter decomposition during winter and over longer periods of time. Here, we conducted a meta-analysis to synthesize litter decomposition studies under different levels of snow cover. Overall, deepened snow significantly enhanced litter decomposition rate and mass loss by 17% and 3%, respectively. Deepened snow enhanced litter carbon loss by 7% but did not impact the loss of litter nitrogen or phosphorus. Deepened snow increased soil temperature, decreased the frequency of freeze-thaw cycles, and stimulated microbial biomass carbon and bacterial biomass during winter, but had no effect on these parameters in summer. The promoting effect of deepened snow cover on litter decomposition in winter is mainly due to its positive effect on microbial decomposition by increasing soil temperature and reducing freeze-thaw cycles exceeded its negative effect on physical fragmentation of litter by reducing freeze-thaw cycles. Our findings indicate that the changes in winter snow cover under global change scenarios can greatly impact winter litter decomposition and the associated carbon cycling, which should be taken into consideration when assessing the global carbon budget in modeling.

中文翻译：

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加深的积雪通过刺激微生物降解加速垃圾分解

降水模式的变化和全球变暖极大地改变了冬季积雪，这可以通过改变土壤微环境或微生物生物量和活性来影响凋落物分解过程。然而，目前尚不清楚积雪如何以及在多大程度上影响冬季和较长时间内的凋落物分解。在这里，我们进行了一项荟萃分析，以综合不同积雪水平下的凋落物分解研究。总体而言，积雪加深显着提高了凋落物分解率和质量损失，分别提高了 17% 和 3%。积雪加深使凋落物碳损失增加了 7%，但不影响凋落物氮或磷的损失。冬季加深的积雪增加了土壤温度，降低了冻融循环的频率，并刺激了微生物生物量碳和细菌生物量，但在夏季对这些参数没有影响。冬季积雪加深对凋落物分解的促进作用主要是由于其通过提高土壤温度和减少冻融循环对微生物分解的积极作用超过了其通过减少冻融循环对凋落物物理破碎的消极作用。我们的研究结果表明，全球变化情景下冬季积雪的变化会极大地影响冬季凋落物分解和相关的碳循环，在建模中评估全球碳预算时应考虑到这一点。