The Paris Region Institute and its biodiversity department ARB (Regional Biodiversity Agency) carried out a three-year study on 36 green roofs. The study, called Grooves (for Green ROOfs Verified Ecosystem Services), ran from 2017 to 2019. The roofs concerned had varied typologies (extensive, semi-intensive, intensive and wildroof) and were spread over the dense urban territory of Paris and its region. The study was based on inventories of plants and invertebrates (including pollinators), and substrate samples to study soil pollution, micro-organisms and water retention capacity. The cooling effect of vegetation was also analyzed on 14 green roofs. The different axes of the study made it possible to show the ecological role of these new urban ecosystems, particularly in terms of floristic diversity – with 70% of native species - faunistic and micro-organisms. These results made it possible to evoke recommendations to promote the reception of biodiversity in roofs and enhance ecosystem services.