Grazing strategy shifts mitigate the negative effects of drought on grassland productivity in Inner Mongolia

• Two shifts in grazing strategies have gradually mitigated the impact of drought on grassland GPP in Inner Mongolia. • Changes in grazing intensity primarily weaken the relationship between drought and GPP by regulating soil moisture and VPD. • The grazing policy implemented in 2000 had the most significant effect on the restoration of desert steppes. • The Subsidy and Incentive System for Grassland Conservation effectively controlled grassland degradation. To mitigate grassland degradation, China has implemented a series of grazing-centered protection policies. However, how different grazing policies regulate grazing intensity to influence the effects of drought on grassland productivity in Inner Mongolia remains underexplored. This study aims to show the contribution of grazing intensity (GI) to the relationship between drought and grassland gross primary productivity (GPP) in Inner Mongolia across different grazing policy periods from 1992 to 2018, and to explore the specific pathways through which GI and drought influence GPP. The results show that in the first phase of grazing policy implementation (2000–2010, GPIP1 period), GI alleviated the negative impact of drought intensity and counts on GPP, whereas in the second phase of grazing policy implementation (2011–2018, GPIP2 period), GI mitigated the negative effects of the Standardized Precipitation Evapotranspiration Index (SPEI) and drought characteristics on GPP. Structural equation modeling results indicate that from the free grazing period (1992–1999, FG period) to the GPIP2 period, the influence of SPEI on GPP first strengthened and then weakened, while the influence of GI on GPP strengthened across different grassland types. These findings confirm changes in grazing strategies have significant implications for the sustainable development of grasslands.