Table6_Impact of Reduced Rainfall on Above Ground Dry Matter Production of Semi-natural Grassland in South Gloucestershire, UK: A Rainfall Manipulation Study.docx

In the United Kingdom, agricultural grasslands cover 40% of the land area, make up 89% of the total agricultural area and are an important land use for ecosystem services and food security. Climate change predictions suggest that the United Kingdom will experience more frequent and severe periods of drought that may impact these grasslands. As part of the Drought Risk and You (DRY) project, a field experiment in which rain shelters reduced precipitation reaching the vegetation by approximately 50%, was set up in the South West of England. The experiment ran for 3 years, from October 2015 to October 2018. The study was carried out at two locations in the catchment of the Bristol River Frome. Both sites were species-rich semi-natural pastures that had received no inputs of fertilizer or herbicide for many years. Automatic weather stations recorded environmental conditions, especially rainfall, within the experimental area. The existing agricultural management regimes were approximated by cutting the vegetation in the plots, by hand, at the appropriate times of year. The effect of rainfall reduction on plant growth was assessed by biomass sampling. At both sites, the rainfall reduction treatment had only small effects on total above ground dry matter production (biomass). These effects were much smaller than the year-to-year variation in total biomass. Our results suggested that well-established permanent pastures in the South West of England were able to tolerate a 3-year period of reduced water supply. The observed year-to-year variation in biomass demonstrated how important the timing of dry weather is for biomass production, and this will be reflected in effects on yield and quality of hay.

在英国，农业草地覆盖了国土面积的40%，构成了总农业面积的89%，对于生态系统服务和粮食安全而言，草地是一种至关重要的土地利用形式。气候变化预测表明，英国将面临更多频发且严重的干旱期，这可能会影响这些草地。作为干旱风险与您（DRY）项目的一部分，在英格兰西南部开展了一项田间实验，该实验通过设置雨棚，将到达植被的降水量减少了约50%。该实验历时3年，从2015年10月至2018年10月。研究在布里斯托尔河弗罗姆流域的两个地点进行。这两个地点都是物种丰富的半自然牧场，多年来未曾施用肥料或除草剂。自动气象站记录了实验区域的环境条件，特别是降雨量。通过在合适的时节手工切割实验区域的植被，来模拟现有的农业管理措施。通过生物量采样评估了降雨量减少对植物生长的影响。在两个地点，降雨量减少的处理对总地上干物质生产（生物量）的影响微乎其微。这些影响远小于总生物量的年际变化。我们的研究结果指出，英格兰西南部已经建立的永久性牧场能够耐受连续3年的水资源减少。观察到的生物量年际变化展示了干燥天气的时机对生物量生产的重要性，这将反映在干草产量和质量的影响上。