湿地生态系统碳通量研究进展

The Progress of Research on Carbon Flux in Wetland Ecosystems

湿地碳循环在全球气候变化中起着重要作用,而湿地碳通量研究是湿地碳循环研究的关键问题。由于湿地独特的土壤、植被以及水文过程,使得湿地碳通量有别于其他类型的生态系统。湿地温室气体特别是CO2和CH4的释放水平具有明显的时空变化特征,其通量变化与许多外部因素相关,包括土壤状况、水文条件、植被类型、外源氮等。对近年来湿地生态系统碳汇功能变化以及影响碳通量相关因子的研究成果进行了系统的分析和综述。现有的研究表明,土壤状况对湿地碳通量影响较复杂,在一定范围内,表层土壤温度与气体排放密切相关,甚至呈正相关关系;土地利用/覆盖也影响湿地碳通量变化,导致湿地温室气体排放增加;水文条件特别是水位高度对湿地CO2和CH4排放的影响不同,高水位不利于CO2排出,CH4则与之相反;植被对湿地碳排放也起到正、负两方面作用,并且物种各异。还讨论了湿地碳通量研究进展的瓶颈问题,特别对植被演替较快的潮滩湿地碳通量研究做了展望。

Wetland plays an important role on carbon cycle and global climate changes. The research on wetland carbon flux is a key of wetland carbon cycle. Carbon flux in wetland distinguishes from that in other types of ecosystems because of special soil, hydrological processes and vegetations. The greenhouse gas emission, especially CO2 and CH4 emission, shows obviously spatial -temporal variation. The carbon flux is related to many exterior factors, including soil environment, hydrological condition, vegetation type, and exogenous nitrogen and so on. This paper analyzed and gave an overview of the changes about wetland carbon sink function and the related factors of influencing wetland carbon flux. The existing results showed interaction between soil and carbon flux was very complex, to some extent, topsoil temperature had obvious relationship with gas discharge flux, even positive correlation between them. At the same time, Land use cover change also affected carbon flux, which increased gas emission; hydrological condition, especially water depth, influenced CO2and CH4 flux by contraries, which was disadvantageous to CO2emission but CH4. Vegetations had both positive and negative effect on carbon flux, which were decided by different vegetation types. In addition, exogenous nitrogen and other nutrient loading also changed the carbon flux and carbon cycle. Based on these researches, this paper discussed the bottleneck of wetland carbon flux progress, especially gave prospects of carbon flux in tidal flat wetland where succession of vegetation communities was very quick.