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.