Title: Does grazing affect the responses of rangeland vegetation to droughts?

Grazing and drought are the major drivers of pasture degradation in Mongolia. It is important to understand how these two drivers interact and influence rangeland ecosystem services that support food supply for the entire nation. This study aimed to examine the effects of drought, grazing, and their interaction on aboveground plant biomass (AGB) in the semi-arid steppe zone of Mongolia, using a 21 year (2000-2020) dataset on air temperature, precipitation, and aboveground biomass. Aboveground biomass surveys were conducted across the zone within a non-grazed fenced area and a comparable grazed area outside the fence. The Standardized Precipitation-Evapotranspiration Index (SPEI) was calculated to assess drought conditions, using air temperature and precipitation. To assess the effects of drought, grazing, and their interaction on aboveground biomass, linear mixed effect models were used. Results showed that the interaction between grazing and the intensity of drought was highly significant (t-value = 5.73, p < 0.001), indicating that the response of aboveground biomass to the intensity of drought differed between grazed and non-grazed areas in the current year. The negative effect of droughts on AGB in non-grazed plots was twice as strong as for grazed plots. The interaction between the previous year's intensity of drought and grazing was highly significant (t-value = 3.24, p < 0.01), indicating that the response of aboveground biomass to the previous year's intensity of drought differed between grazed and non-grazed areas. The previous year's intensity of drought had a negative effect (not significant) on aboveground biomass in the non-grazed plots while there is no significant effect in the grazed plots. My research indicates that grazing modulates the response of aboveground biomass to drought. Therefore, grazing should be considered when designing management strategies for rangelands under future climate change scenarios.