Plants, soil microbes and physical structure jointly regulate natural grassland ecosystem stability across slope scales on the Qinghai-Tibetan Plateau

• Slope aspect is more influential to ecosystem stability than slope position; • Soil physical structure is more important to grassland ecosystem stability than plant and soil microbes. • Plant diversity, microbial diversity and soil structure stability are all positively correlated with ecosystem stability. • The alpine meadow ecosystem stability is more stable than alpine shrub and alpine wetlands sequentially. Numerous theoretical and empirical studies have examined the mechanisms of ecosystem stability by focusing solely on an individual trophic level over long-term periods. However, little is known about the effects of stability drivers across multiple trophic levels and their relative importance at various slope scales. This study addresses this gap by assessing the diversity of plants and soil microbes (bacteria and fungi), soil aggregate composition, and the temporal ecosystem stability using normalized difference vegetation index (NDVI) derived from remote sensing data from 2002 to 2020 across different slope aspects on the Qinghai-Tibetan Plateau (QTP). We quantified the roles of key stability drivers (plants, soil microbes, soil physical structure and soil states) on grassland ecosystem stability. Our findings demonstrate that ecosystem stability on the QTP increases from the upper to the bottom slope positions, following the order: alpine meadow on sunny slopes (MS) > alpine shrubs on shady slopes (SS) > alpine wetlands along riversides (WR). Ecosystem stability is jointly regulated by plants, soil microbes, and soil physical structure, all of which are significantly influenced by slope aspect within the same climatic zone. Soil aggregate composition and MWD contribute the most to ecosystem stability (61.5 %), followed by plant variables (19.7 %), soil microbial variables (15.2 %), and soil conditions (3.6 %). Additionally, plant variables, soil microbes, and soil physical structure affected ecosystem stability both directly and indirectly through their interactions. These results suggest that a comprehensive assessment of grassland ecosystem stability under environmental change requires integrating both above- and below-ground biodiversity together with soil physical structure.