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

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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.