WenJun Zhang School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China Computational Ecology and Software ISSN 2220-721X http://www.iaees.org/publications/journals/ces/online-version.asp 2027 17 2 69 94 International Academy of Ecology and Environmental Sciences Hong Kong 26 August 2026 8 September 2026 1 June 2027 biodiversity ecosystem stability scale beta diversity spatial insurance metacommunity multiscale cascade stability conductance scale resonance The relationship between biodiversity and ecosystem stability has been studied intensively at local scales, but its extension to large spatial scales remains unresolved. This study develops a unified theoretical framework, the Multiscale Diversity-Stability Cascade (MDSC), to explain how biodiversity determines ecosystem stability across local, regional, and macroecological scales. The MDSC posits that large-scale stability is not the simple sum of local stabilities but emerges from a nonlinear cascade involving local alpha stability, spatial beta asynchrony, and regional gamma functional redundancy. beta diversity acts as the pivotal variable, with a hump-shaped rather than monotonically positive effect on regional stability. This study introduces three operational concepts: stability conductance, scale resonance, and the diversity-stability landscape. Stability conductance measures the efficiency with which a change in beta or gamma diversity propagates to a change in regional stability. Scale resonance describes the amplification of regional variability when the spatiotemporal frequency of disturbances matches the intrinsic asynchronous oscillation period of the metacommunity. The diversity-stability landscape maps diversity configurations onto stability states and reveals thresholds, saddle points, and hysteresis. The study derives a hierarchical state equation and a simplified analytic module that links alpha, beta, and gamma components. The study proposes empirical strategies using global observation networks, remote sensing, Bayesian multiscale causal models, and spatially explicit simulations. The framework predicts that intermediate beta diversity maximizes regional stability, that moderate landscape connectivity optimizes stability conductance, and that high beta diversity reduces scale resonance. These results have direct implications for biodiversity conservation and global change early warning. http://www.iaees.org/publications/journals/ces/articles/2027-17(2)/how-biodiversity-determines-ecosystem-stability-at-large-scales.pdf