||Background: In the Arctic region, temperature increases are expected to be greater under anticipated climate change than the global average. Understanding how dark respiration (R-d) of common Arctic plant species acclimates to changes in the environment is therefore important for predicting changes to the Arctic carbon balance. Aims: The aim of this study is to investigate the influence of genotype and growing environment on R-d, the temperature response (Q(10)) of R-d, and foliar N (N-leaf) of the Arctic sedge Eriophorum vaginatum. Methods: We measured R-d, and determined its Q(10) and N-leaf of E. vaginatum populations that were reciprocally transplanted 30 years previously along a latitudinal transect of 370 km in northern Alaska. Results: R-d and Q(10) did not differ among populations (ecotypes) of E. vaginatum, but the local environment had a significant effect on both variables. R-d as well as N-leaf was higher in northern, colder sites, while Q(10) was lower there. Conclusions: R-d in the different populations of E. vaginatum is a very plastic trait and controlled by growing environment, as is N-leaf. The lower Q(10) values in the northern sites were most likely a consequence of substrate inhibition of R-d at higher temperatures.