PDF(Pubmed)
Abstract：
Standing dead trees (snags) are recognized for their influence on methane (CH4) cycling in coastal wetlands, yet the biogeochemical processes that control the magnitude and direction of fluxes across the snag-atmosphere interface are not fully elucidated. Herein, we analyzed microbial communities and fluxes at one height from ten snags in a ghost forest wetland. Snag-atmosphere CH4 fluxes were highly variable (- 0.11-0.51 mg CH4 m-2 h-1). CH4 production was measured in three out of ten snags; whereas, CH4 consumption was measured in two out of ten snags. Potential CH4 production and oxidation in one core from each snag was assayed in vitro. A single core produced CH4 under anoxic and oxic conditions, at measured rates of 0.7 and 0.6 ng CH4 g-1 h-1, respectively. Four cores oxidized CH4 under oxic conditions, with an average rate of - 1.13 ± 0.31 ng CH4 g-1 h-1. Illumina sequencing of the V3/V4 region of the 16S rRNA gene sequence revealed diverse microbial communities and indicated oxidative decomposition of deadwood. Methanogens were present in 20% of the snags, with a mean relative abundance of < 0.0001%. Methanotrophs were identified in all snags, with a mean relative abundance of 2% and represented the sole CH4-cycling communities in 80% of the snags. These data indicate potential for microbial attenuation of CH4 emissions across the snag-atmosphere interface in ghost forests. A better understanding of the environmental drivers of snag-associated microbial communities is necessary to forecast the response of CH4 cycling in coastal ghost forest wetlands to a shifting coastal landscape.
摘要：
站立的枯树（障碍）因其对沿海湿地中甲烷（CH4）循环的影响而受到认可，然而，控制跨越障碍-大气界面的通量的大小和方向的生物地球化学过程尚未完全阐明。在这里，我们分析了幽灵森林湿地中十个障碍高度的微生物群落和通量。堵塞大气的CH4通量变化很大（-0.11-0.51mgCH4m-2h-1）。CH4的产量是在十个障碍中的三个中测量的；然而，在十个障碍中的两个中测量CH4消耗。在体外测定来自每个障碍的一个核心中潜在的CH4产生和氧化。单核在缺氧和有氧条件下产生CH4，测得的速率分别为0.7和0.6ngCH4g-1h-1。四核在有氧条件下氧化CH4，平均速率为-1.13±0.31ngCH4g-1h-1。Illumina对16SrRNA基因序列的V3/V4区域进行测序揭示了不同的微生物群落，并表明了枯木的氧化分解。产甲烷菌存在于20%的障碍中，平均相对丰度<0.0001%。在所有障碍中都发现了甲烷营养生物，平均相对丰度为2％，代表了80％障碍中唯一的CH4循环社区。这些数据表明，在幽灵森林中，CH4排放的微生物可能会减弱。有必要更好地了解与障碍相关的微生物群落的环境驱动因素，以预测沿海幽灵森林湿地中CH4循环对不断变化的沿海景观的响应。
