**5. Conclusions**

Our in situ litterbag experiment quantified 16–21% of the remaining plant litter sequestered as stable humic substances in the substrate material after four years of humification. Although this proportion was small compared with the decomposed amount (57–76%), carbon was retained to a degree in decomposing litter during its early decay periods, when an organo-mineral association formed via the interactions of mineral elements with newly accumulated humus. Clearly, the early carbon sequestration process from plant litter will be limited under a reduction in winter snow cover, although the effect is more complex than previously expected, and more long-term assessments should address how carbon is sequestrated and not decomposed from plant litter under a changing climate in seasonal snow-covered ecosystems.

**Author Contributions:** D.W. and W.D. designed the experiments; X.N. collected and exampled the samples; H.G. analyzed the data and drew the figures; D.W. drafted the manuscript; W.D. revised the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China, gran<sup>t</sup> numbers 32001965 and 41971261.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data are included in the manuscript submitted for peer review and will be archived online as supplementary materials of the manuscript is accepted for publication.

**Conflicts of Interest:** The authors declare no conflict of interest.
