What goes up, must come down: air–soil microbiome connectivity and its implications for ecosystem functioning

Beatriz Sánchez-Parra , Nico Eisenhauer

Soils harbor Earth's largest reservoir of microbial diversity, yet enormous numbers of microorganisms are continuously aerosolized, transported through the atmosphere, and redeposited across landscapes. Although soil and the atmosphere have largely been studied separately, here, we propose a conceptual framework that views soils and the atmosphere as a coupled microbiome linked by bidirectional microbial fluxes. We argue that the atmosphere is not merely a passive transport medium but a selective habitat that filters microorganisms during dispersal, while deposition and subsequent establishment further shape microbial assembly on the ground. This air–soil connectivity operates across local to intercontinental scales, influencing biodiversity and ecosystem resilience. Framing these interactions within a One Health perspective highlights their relevance for ecosystem management, agriculture, restoration, biosecurity, and public health. We identify key research priorities, including quantifying global microbial fluxes, resolving the functional consequences of atmospheric dispersal, and integrating microbial transport into coupled Earth-system models. Recognizing the atmosphere and soils as an interconnected microbiome provides a new framework for understanding microbial biogeography and predicting ecosystem responses under accelerating global environmental change.