Rationales for microbial conservation: A quantitative global assessment

Despite the foundational role microorganisms play in sustaining life on Earth, they have been largely overlooked in global conservation agendas, driving the emergence of microbial conservation as a critical discipline. While major assessment reports successfully mobilize support for the conservation of macroscopic biodiversity by documenting its value, threats, and intervention effectiveness, comparable evidence for microbes is lacking. I provide this missing evidence by synthesizing 33,297 effect sizes across three second-order meta-analyses. These analyses (1) identified land-use and land-cover change as well as specific pollutants as the primary threats to microbial diversity, function, and community integrity, (2) demonstrated the essential ecosystem services microbes provide, and (3) revealed the insufficient microbial conservation gain achieved by existing interventions. Building on these insights, I revisit the concept of vulnerability to propose targeted microbial conservation strategies that maintain or restore microbial diversity and function. The evidence presented here underscores the urgency of integrating microbes into nature conservation, thereby protecting the very foundation of life and safeguarding ecosystem integrity and planetary health.