Nature conservation literature and policy instruments mainly focus on the impacts of human development and the benefits of nature conservation for oceans and aboveground terrestrial organisms (e.g., birds and plants) and processes (e.g., food production), but these efforts almost completely ignore the majority of terrestrial biodiversity that is unseen and living in the soil. Little is known about the conservation status of most soil organisms and the effects of nature conservation policies on soil systems. Yet like “canaries in the coal mine,” when soil organisms begin to disappear, ecosystems will soon start to underperform, potentially hindering their vital functions for humankind. Soil biodiversity and its ecosystem functions thus require explicit consideration when establishing nature protection priorities and policies and when designing new conservation areas. To inform such efforts, we lay out a global soil biodiversity and ecosystem function monitoring framework to be considered in the context of the post-2020 discussions of the Convention on Biological Diversity (CBD). To support this framework, we suggest a suite of soil ecological indicators based on essential biodiversity variables (EBVs) that directly link to current global targets such as the ones established under the CBD, the Sustainable Development Goals (SDGs), and the Paris Agreement.
