Grass half full? Adapting the hydrological management of grazed lowland peatlands to balance climate change mitigation with agriculture

英国超过10%的陆地表面被泥炭覆盖，这是英国最大的碳库。这片土地的大部分现在都经过了排水改造，以支持放牧、农作物种植和林业，因此泥炭地据信每年排放超过1800万吨二氧化碳当量，约占英国所有温室气体(GHG)排放量的4%。其中一半以上的排放来自相对较小的低地泥炭，其中大部分已被转化为耕地和草原农业。这些地区现在是陆地部门温室气体排放最严重的来源之一。在英国政府承诺到2050年实现温室气体净零排放之后，迫切需要减少这些排放，并在可能的情况下恢复泥炭地作为碳汇的自然功能。然而，耗尽的低地泥炭地也支持着英国一些价值最高的农田，将这些地区完全恢复为湿地可能会对英国的粮食安全和农村经济产生严重影响，并可能将我们的排放‘离岸’到我们进口粮食的其他国家。对这一挑战的认识导致了Defra低地农业泥炭工作组的成立，该工作组将于2022年10月发布报告。这份报告预计将就农田下泥炭地的未来管理提出详细建议，例如东英吉利地区的泥炭地，英国环境卫生署和其他机构已经对这些地区进行了广泛的研究。相比之下，草原管理下的泥炭区域，如萨默塞特山和摩尔山，被认为是一个显著的证据差距，尽管它们通常比种植的芬兰泥炭保留更深的泥炭和更大的碳储量。这位博士将寻求解决这一证据差距。

Over 10% of the UK's land surface is covered by peat, representing the country's largest carbon store. Much of this land has now been modified by drainage to support grazing, crop cultivation and forestry, as a result of which peatlands are believed to emit over 18 Mt CO2 equivalent per year, around 4% of all the UK's greenhouse gas (GHG) emissions. Over half of these emissions derive from the relatively small area of lowland peat, the majority of which has been converted to arable and grassland agriculture. These areas are now among the most intense sources of GHG emissions from the land sector. Following the UK Government's commitment to Net Zero GHG emissions by 2050, there is an urgent need to reduce these emissions, and where possible to reinstate the natural function of peatlands as carbon sinks. However, drained lowland peatlands also support some of the UK's highest value farmland, and restoring these areas fully to wetland could have severe impacts on UK food security and the rural economy, as well as potentially 'offshoring' our emissions to other countries from which we import food. Recognition of this challenge led to the formation of the Defra Lowland Agricultural Peat Task Force, which will publish its report in October 2022. The report is expected to make detailed recommendations on the future management of peatland areas under cropland, such as those of East Anglia, which have been extensively researched by UKCEH and others. In comparison, areas of peat under grassland management, such as those of the Somerset Levels and Moors, are recognised to be a significant evidence gap, despite the fact that they typically retain far deeper peat and larger carbon stocks than the cropped Fenland peats. This PhD will seek to address this evidence gap.