Grazing legacy mediates the diverse responses of grassland multidimensional stability to resource enrichment

Long-term grazing and resource enrichment are known to affect grassland ecosystem stability independently. However, the interactive effects of grazing legacy and resource enrichment on ecosystem multidimensional stability (e.g., temporal stability (TS): the degree of constancy of ecosystem components over time and temporal resistance (TR): the ability of ecosystem components to withstand the environmental change) in grassland ecosystems remain underexplored. In this study, we conducted a field manipulation experiment to assess the impact of 4-yr of resource addition (water and nitrogen) on multidimensional stability of multiple ecosystem components and underlying drivers in Inner Mongolia steppe with 7-yr different experimental grazing history. We found that the positive effects of water + nitrogen addition on multifunctional TS increased with increasing grazing intensity and an opposing trend was observed for multifunctional TR response. However, neither grazing legacy nor resource addition had an effect on community compositional stability. Resource addition enhanced the stability of species evenness, CWM (community weighted mean) species biomass and CWM-traits. Furthermore, water + nitrogen additions stimulated soil temperature TS but reduced its TR in heavy grazing intensity, with high grazing intensity bolstering soil moisture stability. Multifunctional stability was primarily governed by species asynchrony, while stability of species evenness fostered compositional stability. In particular, TS of functional diversity enhanced multifunctional TS in light grazing intensity, while TS of CWM-traits promoted multifunctional TS in heavy grazing intensity. Our study underscores the decoupling responses of functional stability and compositional stability to grazing legacy combined with resource enrichment. These findings highlight that the significance of concurrently considering multiple stability dimensions and components for a comprehensive understanding of grassland ecosystem stability under intensifying land use and global change scenarios.