Forest Microbiomes as Hidden Pillars of Biodiversity

Forest biodiversity conservation has largely overlooked the functionally paramount microbial communities, the forest microbiome—that underpin ecosystem health. This “invisible majority” of bacteria, fungi, and other microbes drives fundamental processes like nutrient cycling, soil formation, and plant growth, determining overall ecosystem functioning. However, these vital communities are threatened by anthropogenic pressures such as deforestation, land-use change, and climate change, leading to microbial diversity loss with cascading consequences for ecosystem stability. A paradigm shift is urgently needed to integrate microbial conservation into forest management and restoration, as ignoring this dimension limits the efficacy of current strategies. This review synthesizes our understanding of forest microbiome structure and function, evaluates major threats, and outlines technologies and policies for their conservation. We argue that stewarding forest microbiomes is a prerequisite for achieving global biodiversity and climate goals.