季节性雪被变化对森林凋落物分解及土壤氮动态的影响

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

全球气候变化引发的雪被格局变化将深刻影响植被的凋落物分解、陆地生态系统的土壤养分循环等过程.森林是陆地生态系统的主体,在全球生物地球化学循环中起着不可替代的作用.本研究综述了季节性雪被变化对森林凋落物分解及土壤氮动态的影响.全球气候变化情景下季节性雪被表现出因地域而异的增加或减少的变化格局,一方面通过改变环境温湿度、凋落物质量、分解者动态等直接影响分解过程,另一方面通过改变森林群落结构、植被物候、土壤养分等间接地作用于凋落物分解.同时,季节性雪被通过影响氮富集作用、雪被下土壤温湿度、冻融循环、森林群落、雪下动物和微生物等相关因子而改变森林土壤氮循环.本领域未来应开展的研究是:1)全面考虑全球气候变化情景下季节性雪被格局的变异性,开展不同季节性雪被格局变化的模拟研究;2)开展季节性雪被融雪水淋溶作用对森林凋落物分解和土壤氮动态的影响研究;3)阐明不同生态系统和气候带中季节性雪被格局变化对森林凋落物分解过程和土壤氮动态的驱动机制研究;4)量化季节性雪被变化对森林凋落物分解和土壤氮动态在雪被覆盖期的瞬时影响和无雪期的延续影响,为阐明和模型预测陆地生态系统生物地球化学循环对全球气候变化的响应提供理论基础和数据支持.

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 snowcovered 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.