Mutual feedback between above- and below-ground controls the restoration of alpine ecosystem multifunctionality in long-term grazing exclusion

Grazing exclusion is widely used to restore the grasslands that degraded by overgrazing. However, it is not clear how the interaction of above- and below-ground functioning affects the restoration of ecosystem multifunctionality in long-term grazing exclusion. Here, long-term grazing exclusion experiments were performed in a desertified alpine grassland of eastern Tibetan Plateau. We measured critical ecosystem functioning indices including species diversity, community biomass, soil water content and soil nutrient concentrations. Our results showed that both above- and below-ground functioning increased over restoration time, with the mean values increased by 187%, 112%, 195%, 92% and 242% from GE2 to GE12 for above-ground biomass, soil water content, soil organic matter, soil total nitrogen and soil total phosphorus, respectively. Species diversity tended to an “inverted U curve” over restoration time. The response of belowground functioning lagged behind that of aboveground functioning during the restoration process. The trade-off values between above- and below-ground ecosystem functioning in the early restoration stage was significantly higher (P < 0.01) than that in the late restoration stage. We also found that the feedback of aboveground functioning on belowground functioning shifted from negative in the early restoration stage to positive in the late stage. The findings of this study suggested that the interaction between above- and below-ground functioning controls the restoration of ecosystem multifunctionality. This study is valuable for improving sustainable grassland policies and optimizing desertified grassland management on the Tibetan Plateau.