Linking microbial genes to methane emissions from peatlands under water-table changes

尽管泥炭地只占地球表面的约3%，但它在气候调节（一项关键的生态系统服务）方面发挥着重要作用，储存了全球约三分之一的土壤有机碳。由于人类活动和气候变化引起的干旱，许多天然泥炭地遭到破坏和退化。在英国，估计只有20%的泥炭地处于自然或接近自然的状态。正在作出相当大的努力，通过恢复，主要是通过提高地下水位，来减轻受损泥炭地的碳损失。然而，有证据表明，排水泥炭地的再淹可能会增加这些地点的甲烷（CH4）排放。在100年的时间框架内，甲烷作为温室气体的效力是二氧化碳（CO2）的25倍。令人担忧的是，恢复的泥炭地通过再湿润而增加的甲烷排放可能抵消二氧化碳的缓解。甲烷是由深水缺氧泥炭层中的产甲烷微生物产生的。在更上层更容易获得氧气的地方，甲烷营养微生物通过氧化将一些甲烷转化为二氧化碳。产甲烷和产甲烷营养微生物群落对水文变化的恢复能力，因此，泥炭柱上的氧浓度还没有完全了解。这给研究地下水位动态对这些受到挑战的生态系统中甲烷循环的影响带来了不确定性。本博士研究项目将探索受挑战泥炭地（受损/恢复）地下水位变化过程中甲烷循环生物的分类和功能多样性及其恢复力与甲烷通量之间的关系。这项研究产生的知识有可能影响环境政策，以改善泥炭地恢复期间的水文管理，同时减少温室气体排放。

Despite covering only approximately 3 per cent of the Earth's surface, peatlands play an important role in climate regulation (a key ecosystem service), storing approximately a third of global soil organic carbon. Many natural peatlands have suffered from damage and degradation because of human activities and climate change-induced droughts. In the UK, only an estimated 20% of peatlands are in their natural or near-natural state. Considerable efforts are being made to mitigate the loss of carbon from damaged peatlands through restoration, mostly through raising of the water table. However, there is evidence to suggest that the reflooding of drained peatlands may increase methane (CH4) emissions from these sites. Methane is 25 times more potent as a greenhouse gas compared to carbon dioxide (CO2) over a 100-year timeframe. The concern is that increased CH4 emissions from restored peatlands, through rewetting, could offset CO2 mitigation. Methane is produced by methanogenic microorganisms in the deep waterlogged oxygen-deprived peat layers. In the layers further up where oxygen is more readily available, methanotrophic microorganisms convert some of this methane into CO2 through oxidation. The resilience of methanogenic and methanotrophic microbial communities to hydrological changes and therefore oxygen concentration across the peat column is not fully understood. This brings uncertainty in studying the effects of water table dynamics on methane cycling in these challenged ecosystems. This PhD research project will explore the taxonomic and functional diversity of methane cycling organisms and the relationship between their resilience and methane fluxes during water table changes in challenged peatlands (damaged/restored). The knowledge generated from this research has the potential to influence environmental policy to improve hydrological management during restoration of peatlands while mitigating greenhouse gas emissions.