Fine roots are a key component of carbon and nutrient dynamics in forest ecosystems. Rising atmospheric [CO2] (eCO2) is likely to alter the production and activity of fine roots, with important consequences for forest carbon storage. Yet empirical evidence of the role of eCO2 in driving root dynamics in low-nutrient forested ecosystems is limited, particularly for grassy woodlands, an ecosystem type of global importance. We sampled fine roots across seasons over a two-year period to...