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

土壤微生物作为生态系统中重要的分解者,在对动植物残体以及土壤有机质降解的过程中,一方面释放CO2到大气中,是土壤碳排放的重要组成部分；另一方面,在分解的过程中,形成了可供给植物利用的无机养分.由于温度对代谢活动的直接影响,过去对微生物代谢的研究主要集中在生长季,通常假设冬季土壤微生物的活力可以忽略.陆地表面近60％的区域经历着季节性积雪覆盖和季节性土壤冻结的影响.近年来的研究表明,由于积雪的覆盖,形成很好的绝缘层,雪被下土壤中微生物仍然具有显著的活性,对土壤碳排放和植物的养分吸收具有重要的贡献.本文就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进行了全面的分析,综述了国内外冬季雪下碳氮循环的研究现状,提出了目前研究中存在的问题和未来的研究方向,强调了开展温带冬季雪下土壤微生物碳氮循环研究的必要性和重要性.

Seasonal characteristics of soil CO2 efflux and carbon and nitrogen cycling induced by microorganisms in snow-covered and frozen soil system

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.