Seasonal characteristics of soil CO2 efflux and carbon and nitrogen cycling induced by microorganisms in snow-covered and frozen soil system
积雪和冻结土壤系统中的微生物碳排放和碳氮循环的季节性特征

Soil microorganism, as a key decomposer, has a profound effect on carbon and nutrient cycling in terrestrial ecosystem. Through the decomposition process, microorganisms can return CO2 back to the atmosphere and release nutrients for plants. However, most of the previous study was conducted during the growing season, based on the assumption that microbial activity in frozen or snow-covered soils is negligible. Approximately 60% of the terrestrial earth surface experiences seasonal snow cover and seasonal soil frost. The recently published data has convincingly demonstrated that soil microbial activity in the field occurs at freezing temperatures, including arctic tundra, alpine tundra, boreal forests, wetlands and grasslands. The snow cover could effectively decouple soil temperatures from the atmosphere, resulting in higher soil temperatures; therefore, snow-covered soil microorganisms play important contribution to soil CO2 efflux and plant nutrient uptake. In this paper, we comprehensively analyzed the contribution of snow-covered soil microorganisms to soil carbon release and plant nutrient uptake. In addition, the present status in the research of snow-covered soil carbon and nitrogen cycling was overviewed. Furthermore, we raised major research areas in the future, emphasizing the importance and necessity to conduct the research concerning winter snow-covered ecological processes in tempeate areas.