积雪变化对陆地生态系统植被特征和土壤碳氮过程的影响OACHSSCDCSTPCD

In seasonally snow-covered ecosystem,warmer winters lead to shallow and discontinuous snow packs,accompanied by the earlier snow melting and the declining snow-cover extent.However,compared to the other global changes,such as nitrogen deposition,global warming and precipitation variations,the impacts of snow cover changes on terrestrial ecosystem functions and processes are still unclear.To deepen our understandings on the ecological consequences of the changes in snow cover regime,we summarized the effects of snow cover depth and snow-melting time on plant community composition,litter decomposition,soil carbon and nitrogen pool dynamics,greenhouse gas production/consumption processes,and soil micro-food web(fauna and microorganisms).It was found that,due to the diverse methods simulating snow cover changes and the distinct climate and soil contexts in each individual case,the published observations are conflict and have no general conclusions.For example,under the scenarios of climate warming,shallow snow-cover and earlier snow melting will induce earlier plant phenology,and thus,higher plant productivity and more plant litter.Decreased proportion of grasses in the community will increase the litter quality.The higher temperature in earlier spring will increase the activity of soil microorganisms and litter decomposition rates,which consequently accelerate the carbon and nitrogen turnover processes.In contrast,shallow snow-cover and earlier snow melting might also decrease plant productivity and litter quantity because of low temperature and increased freeze-thaw cycles.The earlier spring drought will decrease the litter quality and microbial activity,and thus,decelerate the carbon and nitrogen cycling processes.The other problems relevant to the research on the impact of snowpack changes on the functions and processes of terrestrial ecosystems include:1)whether there are interactive effects of snow depth and snowmelt time on the ecosystem,and whether the impacts of snow cover changes will last to growing season are not yet fully concerned;2)the effects of snow cover depth and snow-melting time on plant community composition,litter decomposition,soil carbon and nitrogen dynamics,and soil organisms are studied independently;3)the underlying microbial mechanism driving soil biogeocycling processes under snow cover changes are still unclear,in particular,lacking genomic supporting data;4)remote sensing has been rarely applied to inverting various snow parameters relevant to terrestrial ecosystem functions and processes.Thus,we highlighted the importance to strengthen the research on the ecological linkages between plant community,soil carbon and nitrogen processes,and soil micro-food web,soil microbial community composition and function based on genomic analysis,and the application of remote sensing technology,aiming to provide reference for the development of snowpack ecology.