Leaf carbon and nitrogen isotopes, Toolik Lake, Alaska, 2016

We collected leaf gas exchange measurements during three time periods in the 2016 summer, June 19-24, July 12-23 , and August 11-14. Fully-emerged, healthy (not galled or senesced) leaves were used from the four dominant species, Salix pulchra and Betula nana (deciduous shrubs), Ledum palustre (evergreen shrub), and Eriophorum vaginatum (graminoid). Leaves used in gas exchange measurements were oven dried at 40°C and ground to a fine powder with a Mini Beadbeater-16 (Biospec Products Inc., Bartlesville, OK) with 3.2 mm ball bearings. Subsamples were analyzed for N(%) and C(%) and 13C and 15N with a Costech Elemental 4010 elemental analyzer (Costech Analytical, Valencia, CA, USA) linked to a continuous flow isotope ratio mass spectrometer (model DeltaPLUS XP, Thermo-Finnegan Scientific, Waltham, MA) at the University of Alaska-Anchorage.

本数据集采集了2016年夏季三个时段的叶片气体交换实测数据，分别为6月19日至24日、7月12日至23日及8月11日至14日。实验所用叶片采自四种优势物种的完全展开、健康（无虫瘿或衰老症状）个体，物种包括Salix pulchra（美丽柳）、Betula nana（矮桦，落叶灌木）、Ledum palustre（杜香，常绿灌木）以及Eriophorum vaginatum（羊胡子草，禾草类植物）。用于气体交换测量的叶片经40℃烘箱烘干后，使用搭载3.2mm钢珠的Mini Beadbeater-16型珠磨仪（美国Biospec Products公司，俄克拉荷马州巴特尔斯维尔）研磨为细粉。分取子样后，在美国阿拉斯加大学安克雷奇分校，借助与连续流同位素比率质谱仪（型号DeltaPLUS XP，赛默飞世尔科技，马萨诸塞州沃尔瑟姆）连接的Costech Elemental 4010型元素分析仪（美国Costech Analytical公司，加利福尼亚州巴伦西亚），完成了氮含量（%）、碳含量（%）及碳-13（13C）、氮-15（15N）的检测分析。