Grassland ecosystems occupy an important position in global carbon storage.Arbuscular mycorrhizal fungi(AMF)exist widely in these grasslands and play a significant role in the ecosystems ability to act as carbon sinks.This paper summarizes this role from the perspective of the fungis functional diversity.It reviews, 1) the impact of AMF on the net primary productivity of grassland ecosystems,2) their impact on variation in the soil carbon pool,3)the response of AMF to elevated atmospheric CO_2 and increased anthropogenic nitrogen deposition,and 4) how grazing management practices could affect AMF and therefore the carbon cycle of grassland systems.This review is undertaken in order to provide references for evaluating carbon sinks,calculating carbon fixation rates,predicting carbon storage and coping with global climate change.