Root and microbial respiration dominate carbon dioxide efflux in an arctic ecosystem

Ecosystem respiration (ER) is the largest carbon flux out of ecosystems, yet our ability to model this aggregate flux lags behind our ability to model photosynthesis in arctic tundra. Partitioning respiration into its component fluxes is a critical step toward understanding carbon cycle responses to climate change. To partition respiration, I used tissue-scale respiration measurements of mosses, leaves, and roots; ecosystem-level biomass estimates; and an herbicide plant exclusion method. I found that 52% of ER was attributable to microbial respiration and 24% to root respiration near the end of the growing season. Respiration of leaves and roots of Eriophorum vaginatum contributed 6 to 20% of total ER over the course of the season, while mosses contributed between 3 and 8%. My findings contrast with efforts to model ER as an aggregate flux, which typically use only aboveground drivers.