[Effects of changes in seasonal snow-cover on litter decomposition and soil nitrogen dynamics in forests.]

Changes in snow-cover patterns induced by global climate change profoundly influence ecological processes in terrestrial ecosystems, including litter decomposition and soil nutrient cycling. Forest, a major terrestrial ecosystem, plays a crucial role in global biogeochemical cycling. Here, we reviewed the effects of changes in seasonal snow-cover on litter decomposition and soil nitrogen (N) cycling in forests. Global climate change would result in increasing or decreasing seasonal snow-cover depending on local conditions, with direct and indirect effects on forest litter decomposition. The changes in seasonal snow-cover would directly affect decomposition process by changing environmental temperature and moisture, litter quality, and decomposer dynamics, and would indirectly influence decomposition via altering community structure, vegetation phenology, and soil nutrients. Meanwhile, the changes in seasonal snow-cover would modify forest soil N dynamics through changing N enrichment, soil temperature and moisture, freeze-thaw cycle, forest community, subnivean fauna and microorganisms. Further studies in this field should focus on: 1) employing experiments with divergent protocols to simulate diverse changing patterns of seasonal snow-cover under the global climate change scenarios; 2) the effects of the seasonal snowmelt leaching on forest litter decomposition and soil N dynamics; 3) elucidating mechanisms underlying forest litter decomposition and soil N dynamics driven by changes in seasonal snow-cover patterns in different ecosystems and climate zones; and 4) quantifying the instantaneous and prolonged effects of changes in seasonal snow-cover on forest litter decomposition and soil N dynamics in the snow-covered and snow-free seasons, respectively. These studies will provide theoretical basis and solid data support for the understanding and model-prediction of the responses of the biogeochemical cycle in terrestrial ecosystems to global climate change.