An evaluation of plant wax markers to reconstruct long-term vegetation change in peat bog deposits

植物蜡标记重建泥炭沼泽沉积物长期植被变化的评估

• 批准号: NE/H012362/1
• 负责人: Dmitri Mauquoy
• 金额: $ 3.22万
• 依托单位: University of Aberdeen
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH012362%2F1
• 关键词: evaluation; plant; wax; markers; reconstruct

Northern peatlands concentrated in boreal and subarctic regions store as much as one-third of global soil carbon and represent a highly important global carbon dioxide sink, with an amount of stored carbon representing 25-50% of current levels of atmospheric CO2. Their ability to continue to sequester carbon dioxide and their botanical composition under future global warming scenarios is uncertain, but research into their ability to store carbon during former periods of climate change can provide clues to their potential future response. It has already been shown that changes in the rate of carbon accumulation during the Medieval Warm Period and Little Ice Age in raised peat bogs was dependent upon the botanical composition of the peat forming plants. It is therefore vital to reconstruct the local peat forming vegetation when investigating long-term records of carbon accumulation, but this, unfortunately is not always possible, as plant macrofossils do not preserve well in blanket peat bogs and other boreal and subarctic peatland ecosystems. Given this, there is a pressing need to develop alternative techniques to reconstruct peat forming plants from extensive peat bog archive deposits which contain millennial records of carbon accumulation rate changes, and in this way reconstruct the spatial and temporal variability of carbon sequestration. This research seeks to redress this problem by testing the suitability of 'molecular fossils' preserved in peat profiles from UK blanket peat profiles (preservation of macrofossils is frequently poor in these deposits) to reconstruct the former vegetation components. If successful, the reward of this project will be improved understanding of species dependent carbon sequestration during previous periods of climate change, which could prove highly beneficial to inform future carbon management, both internationally and nationally (peat deposits in moorland areas represent the largest terrestrial carbon pool in the UK). Improved long-term base line data for the origin and nature of vegetation changes in peat bogs would also serve to guide and aid conservation of these threatened ecosystems, particularly blanket peat bogs. This would be highly beneficial to stakeholders charged with water collection, agriculture, sport, leisure, and tourism in moorland habitats where peat bog habitats occur. The techniques have excellent promise since their application in a PhD pilot project offered species level identification (of heather) in a buried soil deposit. Testing the value of plant wax biochemical markers as a proxy for peat-bog vegetation will involve three stages. The first stage will be to determine the chemical markers of living, reference material collected from a range of raised/blanket peat bog habitats. This will be followed by analyses of sub-fossil samples of known botanical composition and age from an extensively radiocarbon dated raised peat bog profile with excellent macrofossil preservation. These samples were investigated as part of a major EU 6th Framework funded project ('Accrotelm') and their timely availability represent an excellent opportunity to investigate the fossil plant wax biochemical signatures of samples of known botanical composition. Data on the modern/sub-fossil plant wax biochemical markers from known plant species will then be used in the final proof of concept stage to reconstruct the potential former local vegetation of a blanket peat sample of imperfectly known botanical composition. Peat bog deposits contain detailed records of carbon sequestration rate changes, and also provide proxy-climate data and long-term ecological records to inform conservation policies. UK scientists are world leaders in the analyses of these deposits, and this small project is closely aligned with three of NERC's current strategic science themes on Biodiversity, Sustainable Use of Natural Resources, and Knowledge Exchange to stakeholders.

集中在北方和亚北极地区的北方泥炭地储存了全球三分之一的土壤碳，是一个非常重要的全球二氧化碳汇，其储存的碳量占当前大气二氧化碳水平的25-50%。在未来全球变暖的情况下，它们继续吸收二氧化碳及其植物成分的能力尚不确定，但对它们在以前气候变化时期储存碳的能力的研究可以为它们未来可能的反应提供线索。已经证明，在中世纪温暖期和小冰河期，抬高的泥炭沼泽中碳积累速率的变化取决于泥炭形成植物的植物组成。因此，在研究碳积累的长期记录时，重建当地形成泥炭的植被是至关重要的，但不幸的是，这并不总是可能的，因为植物宏观化石不能很好地保存在地膜泥炭沼泽和其他北方和亚北极泥炭地生态系统中。鉴于此，迫切需要开发替代技术，从包含碳积累速率变化记录的大量泥炭沼泽档案沉积物中重建泥炭形成植物，从而重建碳封存的时空变化。本研究试图通过测试英国地毯式泥炭剖面中保存的“分子化石”的适用性来解决这个问题（在这些沉积物中，宏观化石的保存往往很差），以重建以前的植被成分。如果成功，这个项目的回报将是提高对以前气候变化时期物种依赖的碳固存的理解，这可能对未来的碳管理非常有益，无论是在国际上还是在国内（沼地地区的泥炭沉积物代表了英国最大的陆地碳库）。改善泥炭沼泽植被变化的来源和性质的长期基线数据也将有助于指导和帮助保护这些受到威胁的生态系统，特别是地膜泥炭沼泽。这将对泥炭沼泽栖息地所在的沼地生境中负责水收集、农业、体育、休闲和旅游业的利益相关者非常有益。该技术应用于一个博士试验项目，提供了埋藏土壤沉积物（石南）的物种水平鉴定，具有良好的前景。测定植物蜡生化标记物作为泥炭沼泽植被指标的价值将分为三个阶段。第一阶段将是确定从一系列凸起/地毯式泥炭沼泽生境收集的生物化学标记物和参考材料。随后将对已知植物成分和年龄的亚化石样本进行分析，这些样本来自具有良好宏观化石保存的广泛放射性碳定年的凸起泥炭沼泽剖面。这些样品是作为欧盟第六框架资助项目（“Accrotelm”）的一部分进行调查的，它们的及时提供为研究已知植物成分样品的化石植物蜡生化特征提供了极好的机会。然后，来自已知植物物种的现代/亚化石植物蜡生化标记的数据将用于最后的概念验证阶段，以重建不完全已知植物成分的毯状泥炭样品的潜在前当地植被。泥炭沼泽沉积物包含碳固存速率变化的详细记录，还提供代用气候数据和长期生态记录，为保护政策提供信息。英国科学家在这些沉积物的分析方面处于世界领先地位，这个小项目与NERC当前的三个战略科学主题密切相关，即生物多样性、自然资源的可持续利用和与利益相关者的知识交流。