In order to remediate the negative externalities caused by urbanization, urban planning policies are turning to developing productive and sustainable cities based on the development of nature in the city. The Bises project “Biodiversity of Urban soils in sustainable cities: state of art, interactions between productive/unproductive green spaces and ecosystem services provisions” aims to support this transition through an increase of soil ecology scientific knowledge in urban socio-ecosystems. These breakthroughs are necessary to set multifunctional green spaces. The project is based on a consortium constituted by academic labs ((UMR CEFE, UMR AgroEcologie Dijon, UMR LSE, UMR CESCO, UMR EPhor, UMR IEES-Paris, OSU ECCE Terra) and and a non governmental organization GO (Plante & Cité). It will be deployed in four french metropoles with different biopedoclimatic conditions (Paris, Nancy, Nantes and Montpellier). The main objective is to gain a better understanding of soil organisms in cities and particularly of the spatial and temporal dynamics in various urban land uses: private gardens, parks or urban farms. A challenge will be to evaluate the impact of practices but also colonization process on urban soil biodiversity functions and associated services (support, food production, biomass production, air/water regulation or biocontrol). The scientific originality of the project is based on: • The combination of all the soil fauna taxa (macro, meso and micro-fauna) and microorganisms (bacteria and fungi), which has never been done before at a national scale. • The development and application of approaches based on the linkage of all soil taxa through the calculation of aggregated indicators or multi-phylum interaction webs. • The linkage of academic science and citizen science based on a co-construction at all steps of the scientific process and will help to access to private land uses, which represent an important part of urban green spaces. • A spatially explicit approach on soil biodiversity, which is still limited • The link between soil biodiversity properties, functions and ecosystem services. The scientific program is divided between a coordination Work-package (WP 0) and four-knowledge production WP’s. WP1 is dedicated to sampling design and sampled site selection. WP2 is dedicated to the use of the biodiversity indicators dashboard (biodiversity, functional biodiversity and functions). WP3 will develop aggregated indicators based on WP1 and WP2 outputs and will address the link between biodiversity and Ecosystem services. WP4 is dedicated to dissemination and various citizen science actions. Besides major advances in terms of basic research in soil ecology, macro ecology or functional ecology in urban landscapes, the project will lead to the validation of a dashboard of the biological quality of urban soils for the sustainable management of cities.