Microbial diversity as the next frontier of payments for ecosystem services in nature-positive finance.

Payments for Ecosystem Services (PES) have matured across forests (carbon), watersheds (water quality and quantity), agricultural landscapes (biodiversity), and urban stormwater management. Most biodiversity assessments emphasize insects, fish, and birds. By contrast, schemes that directly measure and reward the microbial diversity, the foundations of ecosystem services in soils, aquatic systems, and urban green spaces, remain scarce. Meanwhile, the Kunming-Montreal Global Biodiversity Framework calls for mobilizing at least USD 200 billion per year by 2030, and the Global Biodiversity Framework Fund has launched; but current flows into PES are limited, and PES explicitly targeting microbes is largely uncharted. This Perspective argues that microbially focused PES is rare and, even when they exist, they tend to be biased toward specific pathogens or pollution indicators. However, measurement, reporting, and verification of various microorganisms are operationally feasible and methods to strengthen source attribution and contribution estimation are now mature; and channeling a share of Nature-Positive finance to microbial ecosystem assessments could jointly advance drinking-water safety, soil health, agricultural resilience, and urban public health. We discuss the importance of microbial-PES in conserving and enhancing ecosystem services.