Data from nitrogen isotopic analyses used to calculate biological nitrogen fixation (BNF) rates and field measurements from lichen, bryophyte, litter, and soil samples in MAT2006 plots, Arctic LTER, Toolik Field Station, Alaska, summers 2022-2023.

This dataset contains nitrogen (N) fixation and isotope data from experimental samples collected at Toolik Lake, Alaska during the 2022 and 2023 growing seasons. Sampling was conducted across multiple block treatments to capture spatial variability and included four substrate types: lichen, moss, litter, and soil. Within each plot, substrates were collected systematically along transects to ensure representative sampling, with lichen samples collected opportunistically due to lower abundance. Samples were incubated in the field under ambient conditions using 15N₂ to measure biological nitrogen fixation (BNF). In 2023, a short-term wetting experiment was conducted to assess the influence of moisture on BNF rates, with subsamples exposed to controlled additions of water. Across both years, data include isotope ratios, incubation conditions, moisture, fresh and dry biomass, and treatment assignments. The dataset provides information on BNF across substrate types, moisture regimes, and fertilization treatments in Arctic tundra. These data support investigation of N cycling processes, the influence of moisture and fertilization on fixation rates, and variability across vegetation types. The dataset is complete for the two field seasons (2022 and 2023) and includes sample- and block-level metadata necessary for reuse in ecological and biogeochemical research.

本数据集涵盖2022年与2023年生长季期间，于美国阿拉斯加州图利克湖采集的实验样品的固氮与同位素数据。采样采用多区组处理方案以捕捉空间变异性，共包含4类基质类型：地衣、苔藓、枯落物与土壤。每个样地内，基质沿样带系统采集以保障采样代表性；因地衣丰度较低，其样品采用偶采方式获取。样品以15N₂在原位环境下培养，用于测定生物固氮（biological nitrogen fixation, BNF）速率。2023年增设短期增湿实验，通过控制性加水处理亚样品，以评估水分对生物固氮速率的影响。两年的数据集均包含同位素比值、培养条件、水分含量、鲜重与干重，以及处理分配信息。本数据集提供了北极苔原内不同基质类型、水分状况与施肥处理下的生物固氮相关数据，可为氮循环过程、水分与施肥对固氮速率的影响，以及不同植被类型间的变异性研究提供支撑。本数据集完整覆盖2022与2023两个野外采样季，包含生态学与生物地球化学研究复用所需的样品级与区组级元数据。