Plant roots play a critical role in ecosystem function in arctic tundra, but root dynamics in these ecosystems are poorly understood. We synthesized available literature on tundra roots, including their distribution, dynamics, and contribution to ecosystem carbon and nutrient fluxes, and we highlighted key aspects of their representation in terrestrial biosphere models. These measurements served as the baseline of the FRED root trait database, and are also a jumping off point for the new ‘Arctic Underground’ working group.