Plant leaf tissue nitrogen and carbon content for samples collected under experimental warming or ambient conditions near Kangerlussuaq, Greenland, summer 2023

During the 2023 field season at a study site near Kangerlussuaq, Greenland, we collected multiple samples of three key caribou forage plants for chemical analysis. These included a graminoid (Poa pratensis), dwarf birch (Betula nana), and gray willow (Salix glauca). These samples were collected on multiple dates throughout the 2023 growing season for assessment of within season variation in plant leaf nitrogen content (%N by dry mass), carbon content (%C by dry mass), and carbon to nitrogen ratio (by dry mass, an index of forage quality). We also conducted a warming experiment using standardized protocols of the International Tundra Experiment to elevate near surface temperature on multiple plots from which Betula and Salix samples were collected at the end of the 2023 growing season. Our original plan included collecting graminoid (Poa) samples from experimentally-warmed plots as well, but unforeseen conditions at the field site, including unusual flooding of graminoid meadows, precluded such collections. Data on %N, %C, and C:N ratios of samples are provided here. All plant tissue samples were dried at 60C for at least 24 hours and submitted to the UC Davis Analytical Laboratory for ashing and determination of chemical content.2023年野外工作季期间，在格陵兰康克鲁斯瓦格（Kangerlussuaq）附近的研究样地，我们采集了三种核心驯鹿饲用植物的多份样本用于化学成分分析。所涉物种包括禾本科草本（草地早熟禾，Poa pratensis）、矮桦（Betula nana）以及灰柳（Salix glauca）。我们在2023年生长季的多个采样节点收集上述样本，以评估植物叶片氮含量（以干重计的%N）、碳含量（以干重计的%C）及碳氮比（以干重计，作为饲用质量评价指标）的季内变异规律。此外，我们采用国际冻原实验（International Tundra Experiment）的标准化操作规程开展增温实验，对多个样地的近地表温度进行升高处理，并于2023年生长季末期从这些样地中采集了矮桦与灰柳样本。原计划中，我们同样拟从增温实验样地采集禾本科草本（早熟禾属，Poa）样本，但野外样地出现了未预见的状况，包括禾草甸的异常积水，导致无法完成该类样本的采集工作。本数据集提供了所有样本的%N、%C及碳氮比相关数据。所有植物组织样本均在60℃条件下干燥至少24小时，随后送往加州大学戴维斯分校分析实验室（UC Davis Analytical Laboratory）进行灰化处理与化学成分定量测定。