Leaf isotopic (δ 13 C and δ 15 N) and nitrogen contents of Carex plants along the Eurasian Coastal Arctic: results from the Northeast Passage expedition

We conducted surrogate in-situ physiological performance measures (δ 13 C and δ 15 N) of Carex plants from 15 Eurasian Coastal Arctic sites. Leaf carbon isotope discrimination (LCID) of Carex plants exhibited significant differences between sites (populations). Additionally, LCID was inversely correlated with mean annual temperature and stomatal density, and to a lesser extent, with the depth of thaw. Leaf δ 15 N values of Carex plants exhibited significant differences between sites without differences among ramet age classes, and the leaf δ 15 N values were inversely correlated with mean annual precipitation. These ranges of Carex leaf gas exchange and mineral nutrition across the Eurasian Arctic may contribute to Carex ’s dominance in coastal tundra systems. Also, the inverse correlation between LCID, precipitation, and temperature indicates that, as precipitation increases and temperatures continue to warm in Eurasia, leaf gas exchange may actually be lower in the future, leading to reductions in shoot growth and lower above-ground biomass production.