Investigating the timing and causes of nitrogen cycle changes in Bronze Age Ireland

“通过对野生和驯化的动物遗骸进行同位素分析，确定了爱尔兰青铜时代氮循环的根本变化，并将其归因于这一时期加强的土地管理(Guary等人)。2018年)。这一转变的时机与青铜时代中期(公元前1600年)和青铜时代晚期(公元前1000年)广泛开垦土地的孢粉学证据基本一致，这支持对环境转变的人为解释(Plunkett 2009)，但不能排除气候驱动因素。该项目将通过对沉积序列的古环境分析和跨越青铜时代的饮食证据的检查，来调查氮分馏转移的时间、程度和潜在原因。具体的研究问题包括：1)在沉积序列中是否可以检测到氮的转移，包括不太可能受到集约化耕作直接影响的泥炭地？2)考古记录是否准确地反映了青铜时代土地利用的程度，以及在感兴趣的时期是否可以检测到加剧？3)根据考古记录中的多代理古饮食信息确定的生存记录中土地利用的变化是如何体现的？4)土地利用和/或氮转移与这一时期的气候变化(如果有的话)有什么关系？方法1)在爱尔兰青铜时代活动密度不同的地区，从合适的湖泊和泥炭地采集古环境序列(根据岛上两个司法管辖区的遗址和古迹记录确定)。将使用测年和14C测年来分离这些序列的青铜时代水平，然后将在百年尺度上调查土地利用历史(花粉分析)、古气候(花粉流入；仅限遗迹变形虫泥炭地)和三角洲-N-15分析。将在重大过渡时期进行更高分辨率的分析，以便能够精确确定这些事件的时间。2)将使用来自爱尔兰青铜时代考古遗址的考古植物学、考古动物学和人类遗骸的稳定同位素分析来研究土地利用变化、生存和饮食之间的关系。之前发布的数据将与新生成的数据一起纳入研究。这种多代理方法将包括爱尔兰史前第一次对土地利用变化、饮食和环境影响的综合调查，并将使人们能够更深入地了解人类在推动系统性生态系统变化方面的作用。“

"A fundamental alteration in the nitrogen cycle during the Bronze Age in Ireland has been identified through isotope analysis of wild and domesticated faunal remains and attributed to intensified land management during this time (Guiry et al. 2018). The timing of the shift broadly coincides with palynological evidence for widespread land clearance in the Middle Bronze Age (~1600 BCE) and Late Bronze Age (~1000 BCE) that supports an anthropogenic explanation for the environmental shift (Plunkett 2009) but a climate driver cannot be ruled out. This project will investigate the timing, extent and potential causes of the nitrogen fractionation shift through a palaeoenvironmental analysis of sedimentary sequences and an examination of dietary evidence spanning the Bronze Age. Specific research questions include: 1) Is a nitrogen shift detectable in sedimentary sequences, including peatlands which were unlikely to have been directly impacted by intensified farming?2) Does the archaeological record accurately reflect the extent of Bronze Age land-use, and can intensification be detected during the period of interest?3) How do changes in land-use manifest in the subsistence record, determined from multi-proxy palaeodietary information from the archaeological record?4) What was the relationship of land-use and/or nitrogen shifts, if any, to climate change during this period? Methods1) Palaeoenvironmental sequences will be collected from suitable lake and peatland sites in areas demonstrating contrasting densities of Bronze Age activity in Ireland (determined from Sites and Monuments Records in the two jurisdictions of the island). Tephrochronology and 14C dating will be used to isolate the Bronze Age levels of the sequences, which will then be investigated at centennial-scale resolution for land-use history (pollen analysis), palaeoclimate (pollen influx; testate amoebae - peatlands only) and delta-N-15 analysis. Higher resolution analysis will be conducted across periods of major transitions to enable the timing of those events to be refined.2) The relationship between land-use changes, subsistence and diet will be investigated using stable isotope analysis of archaeobotanical, archaeofaunal and human remains from a selection of Bronze Age archaeological sites in Ireland. Previously published data will be integrated into the study alongside newly generated data. This multi-proxy approach will comprise the first integrated investigation of land-use changes, diet and environmental impacts in Irish prehistory and will enable a deeper understanding of the role of humans in driving systemic ecosystem change."