Enriched Background Isotope Study (EBIS): Analysis of 14C-Enriched Carbon Cycle in Soils and Litter at Forested Oak Ridge and AmeriFlux Sites, 2001-2011

These data provide a record of the multi-year, multi-institutional Enriched Background Isotope Studies (EBIS) projects that ran from 2000 through 2011. Elevated levels of 14C enriched CO2 in the air and soil atmosphere as well as leaf, stem, and root tissues were observed on the Oak Ridge Reservations (ORR) during the summer of 1999, and were attributed to local incinerator activities on and/or near the ORR (Trumbore et al. 2002). The isolated enrichment of the background levels of 14C in local forest ecosystem represented a unique opportunity to study unresolved carbon cycling processes such as the contribution of leaf versus root litter contributions to soil carbon accumulation, the rate of vertical transport of carbon into deep soil storage pools, and the differential contribution of physicochemical versus faunal driven processes to soil carbon cycling and sequestration. Leaf litter from the local enriched forest was transplanted to selected sites on the ORR and to selected AmeriFlux study sites to study soil C cycling across a range of soils and climates. The EBIS research projects provide data on C flux from litter sources to mineral soil sinks for United States eastern hardwood forests necessary for testing process hypotheses and judging efficacy of soil C cycling models. Experimental results from this study are being used to parameterize and refine existing carbon dynamics models, the quantification of the long-term fate of ecosystem carbon inputs and as a means to judge the potential for ecosystem carbon sequestration via enhance litter inputs to soil. EBIS observations support conclusions that intra- and inter-annual soil carbon cycling in hardwood forest soils should be characterized as a least a two-compartment system where surface leaf-litter and belowground root turnover represent primary carbon sources for organic-layer and mineral-soil carbon cycles, respectively. EBIS experiments were conducted to complete enriched litterfall maniplations in upland forests on Ultisol and Inceptisol soils of the Oak Ridge Reservation, Oak Ridge, Tennessee. We also collected additional14C-enriched materials for new experimental applications, and applied those materials to multiple AmeriFlux sites over a range of climatic, edaphic and biological conditions. The research provided data for addressing DOE's goal of understanding mechanisms controlling C flux, and for the improvement of models to be applied to policy discussions regarding the safe levels of greenhouse gases for the earth's system. There are 5 data files provided in comma separated (*.csv) format for vegetation, field litter, soil and air [C] and C isotope data from the EBIS studies and associated environmental data.本数据集记录了2000年至2011年间开展的多年度、多机构背景同位素富集研究（Enriched Background Isotope Studies，EBIS）项目。 1999年夏季，研究者在橡树岭保护区（Oak Ridge Reservation，ORR）的空气、土壤大气以及叶片、茎秆和根系组织中，观测到富集碳-14（¹⁴C）的二氧化碳浓度升高现象，该现象被归因于保护区内及周边的当地焚烧炉活动（Trumbore等，2002）。 当地森林生态系统中背景水平¹⁴C的孤立富集现象，为研究尚未明确的碳循环过程提供了独特契机：例如叶片凋落物与根系凋落物对土壤碳累积的相对贡献、碳向深层土壤储库垂直运移的速率，以及物理化学过程与动物驱动过程对土壤碳循环及固存的差异化贡献。 研究团队将该富集森林的叶片凋落物移栽至橡树岭保护区内选定样地，以及美国通量网（AmeriFlux）的选定研究样地，以探究不同土壤与气候条件下的土壤碳循环过程。 EBIS研究项目提供了美国东部硬木森林中，从凋落物源到矿质土壤汇的碳通量数据，这类数据可用于验证碳循环过程假说，并评估土壤碳循环模型的有效性。 本研究的实验结果已被用于参数化并优化现有碳动态模型，量化生态系统碳输入的长期归宿，同时作为评估通过向土壤添加凋落物以提升生态系统碳固存潜力的依据。 EBIS观测结果支持以下结论：硬木森林土壤的年内与年际土壤碳循环可被定义为至少双库系统，其中地表叶片凋落物与地下根系周转分别为有机层与矿质土壤碳循环的主要碳源。 EBIS实验于田纳西州橡树岭的橡树岭保护区内的高地森林开展，针对老成土（Ultisol）与始成土（Inceptisol）土壤开展富集凋落物输入调控实验。 研究团队还收集了额外的¹⁴C富集材料用于新实验，并将这些材料应用于不同气候、土壤与生物条件下的多个美国通量网样地。 本研究获取的数据可用于实现美国能源部（Department of Energy，DOE）的研究目标：阐明控制碳通量的机制，并改进模型以支撑关于地球系统温室气体安全阈值的政策讨论。 本数据集共包含5个逗号分隔值（*.csv）格式的数据文件，涵盖EBIS研究相关的植被、野外凋落物、土壤与空气碳及碳同位素数据，以及配套的环境数据。