Biodiversity on Earth is strongly affected by human alterations to the environment. The majority of studies have considered above ground biodiversity, yet little is known about whether biodiversity changes below ground follow the same patterns as those observed aboveground. It is now established that communities of soil biota have been substantially altered by direct human activities such as soil sealing, agricultural land-use intensification, and biological invasions resulting from the introduction of non-native species. In addition, altered abiotic conditions resulting from climate change have also impacted soil biodiversity. These changes in soil biodiversity can alter ecosystem functions performed by the soil biota, and therefore, human-induced global changes have a feedback effect on ecosystem services via altered soil biodiversity. 

Stefan Geisen and colleagues highlight the major phenomena that threaten soil biodiversity, and we propose options to reverse the decline in soil biodiversity. They argue that it is essential to protect soil biodiversity as a rich reservoir that provides insurance against the changes wrought by the Anthropocene. Overall, there is a need to better understand the determinants of soil biodiversity and how they function, plan to avoid further losses, and restore soil biodiversity where possible. Safeguarding this rich biotic reservoir is essential for soil sustainability and, ultimately, the sustainability of human society.