Soil biodiversity knowledge and use worldwide: results from a global survey.

Soil biodiversity is a major component of global biodiversity, but remains poorly characterized in many locations, and is under threat mainly due to land use change and intensification. Detailed assessments of soil biodiversity and a better knowledge of the ecology and distribution of soil organisms worldwide are needed to address threats to soil function, and potential impacts on ecosystem service delivery. A worldwide expert survey was conducted in March 2022 to identify who is doing what, where and how, as well as the main gaps, pitfalls and opportunities across existing national initiatives and research. The questions addressed microbes, fauna and their activity in soils, community and functional assessments, inventories, mapping and monitoring activities, ecosystem services, applications, threats to soil biodiversity, education and communication activities, and public policies related to soil biodiversity. Over 2,000 responses were received, from >1,350 institutions and 135 countries, mainly from experts in research and academia. Respondents worked mostly with soil microbes, focusing primarily on bacteria (85%) and fungi (79%) and less on Archaea, Algae, soil viruses and lichens. Most applied genomic or molecular techniques, as well as activity and process measurements. Soil fauna was less studied overall, with few respondents active in taxonomy (19-34% depending on the taxon). Fifty countries reported inventories, and 48 had monitoring programs, though most (>65%) covered only microbes and fewer (<50%) addressed fauna taxa. A wide variety of methods were used to assess soil fauna and they were widely used as bioindicators. The survey highlighted the lack of studies on the valuation of multiple ecosystem services provided by soil biota, and the poor knowledge on public policies regarding soils and its biodiversity. We identified a need for harmonized global-scale sampling and measuring protocols that are integrated into conventional soil surveys and soil health assessments, as well as approaches that consider multiple taxonomic groups, to provide key information to support policy agendas aimed at soil conservation and sustainability and to propose a design for a Global Soil Biodiversity Observatory.