Dominant species rather than plant biodiversity shape grassland resistance and recovery in response to heatwaves and mowing

Abstract Ongoing climate change has increased the frequency and intensity of climate extremes such as heatwaves, impacting terrestrial ecosystems. Grasslands are often shaped by human activities such as mowing, which may modulate their responses to climate extremes. However, the mechanisms underlying such responses and the factors important in stabilizing grassland functioning under environmental disturbance are currently poorly understood. In this study, we experimentally compared the effects of heatwaves and mowing on the functioning (based on CO 2 exchange) of two different grassland types, Stipa krylovii typical grassland ( Sti ‐Tpl) and Leymus chinensis meadow steppe ( Ley ‐Mdw), in Inner Mongolia. In each grassland, ecosystem CO 2 fluxes and plant community characteristics (biomass, community structure and biodiversity indices) were recorded. We specifically focused on the stability of grassland CO 2 exchange during heatwave events (resistance), the capacity to regain functionality afterwards (recovery) and the plant factors influencing these resilience metrics in both grasslands. The results indicate non‐linear temporal trajectories in carbon flux recovery, with a weak correlation between resistance and recovery. Ecosystem respiration (RE) generally exhibited greater resistance and recovery to heatwaves than gross ecosystem production (GEP); GEP reduction led to a decrease in net ecosystem production (NEP). However, local mowing practices partially mitigated these negative effects. The importance value (Iv) of dominant species and biodiversity both positively influenced NEP resistance, but their effects on NEP recovery were opposite, as Iv enhanced recovery while biodiversity reduced it. Finally, the contribution level of dominant species to grassland stability was closely related to their Iv in the plant community. Synthesis . In this study, we investigated the complex factors influencing ecosystem resistance and recovery to heatwaves and mowing in two distinct grasslands. We found that the physiology, morphology and regeneration traits of the dominant species in each grassland community explained most of the divergence of grassland function stability. Thus, to buffer ecosystems against adverse impacts of climate extremes in conjunction with land management, it can be advantageous to focus on the maintenance or selection of dominant species rather than solely on increasing species richness.