环境和微生物因子对隆宝滩不同植被类型土壤甲烷通量的影响

Effects of Environmental and Microbial Factors on Soil Methane of the Different Vegetation Types at Longbaota Natural Reserve

以位于青藏高原中部的隆宝滩国家级自然保护区为对象,使用便携式温室气体分析仪分别对高寒草地(Alpine grassland,AG)、沼泽化草甸(Marsh meadow,MM)和高寒沼泽(Alpine marsh,AM)的CH4通量进行原位观测,同时分析生物量、微生物、土壤营养元素、土壤温湿度等因子,旨在通过相关分析获得不同植被类型CH4通量差异及其与环境和微生物因子的关联。结果表明,生长季节中不同植被类型CH4通量具有明显的时空差异,MM和AM中的CH4通量较高,在9月达到峰值,AG表现为CH4吸收,在8月达到谷值,AG的CH4通量与MM和AM差异显著(P<0.05)。AG的土壤有机碳、总氮、生物量显著低于MM和AM(P<0.05),而全钾则相反。AG土壤中产甲烷菌mcrA基因丰度显著低于其他2种植被类型,而甲烷氧化菌pmoA丰度则相反(P<0.05)。相关分析显示,CH4通量与土壤湿度、有机碳、总氮、生物量和mcrA显著正相关(P<0.05)。总之,隆宝滩湿地AG的CH4通量与其他2种植被类型的差异是由于碳源、微生物和土壤温度湿度等因素的不同造成的,高寒湿地中不同类型植被CH4通量差异的确定可为精确估算青藏高原高寒地区的CH4排放提供数据支持。

The CH4 fluxes of alpine grassland(AG),Marsh meadow(MM)and alpine marsh(AM)were measured in situ using portable greenhouse gas analyzer in Longbaotan,a National Nature Reserve located in the middle of Qinghai-Tibet Plateau,during the growing season in 2018.Furthermore,biomass,microorganism,soil nutrient,soil temperature and humidity were measured in the soil of the three vegetation types.The difference of CH4 flux for different vegetation types and its correlation with environment and microbial factors were obtained through correlation analysis.The results showed that the temporal-spatial differences of CH4 fluxes among the three different vegetation types were obviously different in the growing season.CH4 fluxes of MM and AM were higher and had a peak in September.Conversely,AG was a CH4 sink and had a minimum value in August.CH4 fluxes of AG were significantly lower than those of MM and AM groups(P<0.05).The organic carbon,total nitrogen and biomass of AG were significantly lower than those of the other two types,but the reverse pattern was observed in total potassium(P<0.05).The mcrA gene abundance of Methanogens in AG was significantly lower than those of the other two groups(P<0.05),while the reverse pattern was observed in the pmoA gene abundance of Methanotrophs.Pearson correlation coefficient showed that CH4 flux was significantly positively correlated with soil humidity,organic carbon,total nitrogen,biomass and mcrA abundance(P<0.05).In a word,the CH4 flux of alpine grassland in longbaotan wetland was different from those of the other two vegetation types due to different carbon sources,microorganisms and soil temperature and humidity.The CH4 flux difference of different vegetation types in alpine wetland can provide data support for accurate estimation of CH4 flux in the Qinghai-Tibet Plateau.