1. The turnover of litter layer is a biogeochemical process fundamental to carbon and nutrient cycling, influencing seed germination, species coexisting, and carbon storage. Winter snow depth is undergoing increasing trend in Northern China, which has been shown to alter litter decomposition rate of individual species. However, it remains unknown how changes in snow depth affect the turnover rate of the whole litter layer, and whether the responses vary between different steppes. Most current litter decomposition studies are site-based or short-term treated, limiting the exploration of the long-term response of litter layer turnover in regional pattern.

2. In this study, we selected six long-term (11–13 years) snow fence sites in Inner Mongolia, with three in the dry steppe and another three in the wet steppe, and investigated the responses of community-weighted litter residence time (LRT) to long-term increased snow treatment.

3. We found that LRT increased by 0.02 year for every 10 cm increase in snow depth in the wet steppe, but was not affected in the dry steppe. The lack of effect of deepened snow on LRT in the dry steppe was attributed to the offset between the positive effect of the increased plant community-weighted height possibly via inhibiting photodegradation and the enhanced litter recalcitrance by producing higher proportion of stem litter, and the negative effect of the increased soil moisture via accelerating microbial decomposition. The significantly positive effect of the deepened snow on LRT in the wet steppe was mainly because the deepened snow increased grass biomass but had no effect on forb biomass, which reduced the degradability of the litter layer.

4. Overall, our findings indicated that deepened snow changed plant community, which altered environmental conditions and enhanced litter recalcitrance, thereby increasing LRT in temperate steppes. However, this effect was diminished by enhancing microbial decomposition in the dry but not wet steppe, resulting in different overall responses of LRT to deep-snow in the two steppes. The slow litter turnover rate in the wet steppe might result in greater litter accumulation under future increased snow depth, which could be unfavourable for seed germination and alter plant diversity.