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 significant changes in Northern Hemisphere, 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 response depends on background climate. Most current litter decomposition studies are site-based or short-term treated, limiting the exploration of the long-term response of litter layer turnover process in regional pattern. In this study, we selected six long-term (11-13 years) snow fence sites in Inner Mongolia, with three in typical steppes and another three in meadow steppes, and investigated the responses of community-weighted litter residence time (LRT) to long-term increased snow treatment.
Results/Conclusions
We found that along with the increased snow depth, LRT showed no response in typical steppes, whereas significantly increased in meadow steppes. The insignificant effect of deepened snow on LRT in typical steppes was attributed to the offset between the positive effect of the increased plant community-weighted height possibly via inhibiting photodegradation and the negative effect of the increased soil moisture via accelerating microbial decomposition. The significantly positive effect of the increased snow depth on LRT in meadow steppes was mainly due to both the positive effect of the increased plant community-weighted height and the positive effect of the increased grass/forb ratio via decreasing litter quality. Our findings indicated that the combination of the increased litter production and longer litter layer residence time might result in greater litter accumulation under future increased snow depth, which could be unfavorable for seed germination and alter plant diversity.