青藏高原草地生态系统碳循环研究进展

Advance in studies of carbon cycling on alpine grasslands of the Qinghai-Tibetan Plateau

青藏高原属于气候变化的敏感区和生态脆弱带,对气候变化和人类活动扰动十分敏感,在未来全球碳循环调控中发挥着重要的作用。为增进对青藏高原高寒草地生态系统碳循环的理解,综述了近10年来气候变化、氮沉降和人类活动干扰下青藏高原温室气体排放、土壤碳库变化以及模型模拟应用等方面的最新研究进展。概括出高寒草地生态系统碳循环研究的草地类型主要包括高寒草原、高寒草甸、灌丛草甸草原、沼泽化草甸以及高寒湿地等。阐述了温室气体产生的机理、青藏高原高寒草地碳循环的源汇关系,指出温度升高、放牧、氮沉降是影响青藏高原温室气体排放、土壤碳库变化最重要的外界扰动,但是温室气体排放、土壤碳库对这3个因子之间协同作用的响应目前还不清楚。现有的高寒草地生态系统碳循环模型,主要以植被类型为基础,大多只考虑了水热因子,很少包含土壤因子和生物因子及其协同作用的影响。在此基础上,指出未来拟加强的研究重点:1)冻融交替过程土壤温室气体排放研究;2)非生长季土壤呼吸作用研究;3)碳循环和植物物候耦合研究;4)高寒草地生态系统碳循环模型的开发。

The Qinghai-Tibetan Plateau is susceptible to climate change and anthropogenic perturbation,due to its fragile ecosystems which play a vital role in mediating future global carbon cycling.To enhance our understanding of the carbon cycling of alpine grassland on the Qinghai-Tibetan Plateau,green-house gases emissions,changes of soil carbon pools,and modeling applications were reviewed in the context of global change,nitrogen deposition and human disturbances,based on research over the last decade.Generally,most attention has been focused on alpine steppe,alpine meadow,shrubland meadow steppe,swamp meadow and alpine wetland.Additionally,The mechanism of greenhouse gas emissions and the shift between source and sink of alpine grassland are summarised.Rising temperatures,grazing activity and nitrogen deposition all exerted significant impacts on greenhouse gas emissions and carbon cycling.However,the responses of carbon cycling to simultaneous changes of these factors is still unknown.On the basis of vegetation type,most recent carbon cycling models failed to incorporate the modulation between biotic and abiotic factors and their relationships.Finally,it was noted that the following four areas required special attention in future studies： 1） greenhouse gas emissions in the course of freeze and thaw cycles;2） soil respiration observation during non-growing seasons;3） coupled study on carbon cycling with plant phenology;and 4） the development of some suitable carbon cycling models for alpine grassland.