Relation between methanogenic archaea and methane production potential in selected natural wetland ecosystems across China

摘要

Methane (CH₄) emissions from natural wetland ecosystems exhibit largespatial variability at regional, national, and global levels related totemperature, water table, plant type and methanogenic archaea etc. Tounderstand the underlying factors that induce spatial differences inCH₄ emissions, and the relationship between the population ofmethanogenic archaea and CH₄ production potential in natural wetlandsaround China, we measured the CH₄ production potential and theabundance of methanogenic archaea in vertical soil profiles sampled from thePoyang wetland in the subtropical zone, the Hongze wetland in the warmtemperate zone, the Sanjiang marsh in the cold temperate zone, and theRuoergai peatland in the Qinghai-Tibetan Plateau in the alpine climate zone.The top soil layer had the highest population of methanogens (1.07–8.29 × 109 cells g?1 soil) in all wetlands except the Ruoergaipeatland and exhibited the maximum CH₄ production potential measured atthe mean in situ summer temperature. There is a significant logarithmiccorrelation between the abundance of methanogenic archaea and the soilorganic carbon (R2 = 0.72, P < 0.001, n = 13) and between the abundanceof methanogenic archaea and the total nitrogen concentrations (R2 = 0.76, P < 0.001, n = 13) in wetland soils. This indicates that the amount ofsoil organic carbon may affect the population of methanogens in wetlandecosystems. While the CH₄ production potential is not significantlyrelated to methanogen population (R2 = 0.01, P > 0.05, n = 13), it isrelated to the dissolved organic carbon concentration (R2 = 0.31, P = 0.05, n = 13). This suggests that the methanogen population might be not aneffective index for predicting the CH₄ production in wetlandecosystems. The CH₄ production rate of the top soil layer increaseswith increasing latitude, from 273.64 μg CH₄ kg?1soil d?1 in the Poyang wetland to 664.59 μg CH₄ kg?1 soil d?1 in the Carex lasiocarpa marsh of the Sanjiang Plain. We conclude that CH₄production potential in the freshwater wetlands of Eastern China is mainlyaffected by the supply of methanogenic substrates rather than temperature;in contrast, low summer temperatures at high elevations in the Ruoergaipeatland of the Qinghai–Tibetan Plateau result in the presence of dominantspecies of methanogens with low CH₄ production potential, which in turnsuppresses CH₄ production.