Urban Microfarms: Hot or Cold Spots for Plants and Soil Biodiversity?

Urban agriculture plays a key role in urban ecosystems functionality and resilience, and can take many forms: allotment gardens, community garden or urban microfarms. In the latest, urban microfarms can be developed at the soil surface but also on rooftops because of the scarcity of space. The soils of these urban microfarms, either pseudo‐natural or Technosol, are also characterised by a high variability in their biological and geochemical properties, influencing their ability to support soil biodiversity. This study investigated the biodiversity (taxonomic richness and abundance) of microorganisms, mesofauna, macrofauna and plant and linked it to soil geochemical parameters in urban microfarm soils. Biological and soil samplings and vegetation identifications were conducted in 12 plots of urban microfarms of the Paris region (France), including 7 plots on the ground level and 5 on rooftops, with characterisation of microbial, collembolan, macrofauna and plant communities and abiotic parameters. There was a very high intra‐ and inter‐site variability within urban microfarms soils, regardless of the taxonomic group considered. Ground microfarms appeared to favour abundance and diversity of spontaneous plants and macrofauna, while rooftop microfarms seemed to harbour more microorganisms (especially bacteria) and Collembola, which were also more diverse, in relation with the characteristics of the two types of soil. Based on our findings we share recommendation for future studies supporting the development of urban agriculture.