Technosols made of urban wastes are suitable habitats for flora and soil macrofauna

Cities are increasingly recognized as specific ecosystems, in which green infrastructures, gardens, parks… can offer new habitats to flora and fauna. Cities also have a limited ability to recycle waste, which could be improved by transforming certain construction waste into Technosols. Here, we show that Technosols made of “fine earth”, excavated from deep soil horizons and usually deposited in landfills by the building sector, can promote plant growth, plant diversity and soil macrofauna. A four-year follow-up showed diversity and abundance levels comparable to temperate meadows. It also suggests a strong potential in terms of carbon storage. This solution could thus simultaneously supply a resource for local green spaces, reduce construction waste in landfills, lessen topsoil removal from neighboring environments, helping cities to take their part in climate change mitigation and biodiversity conservation efforts. • The building sector needs place to store construction wastes such as “fine earth”. • Fine earth could be recycled as Technosols for urban green-spaces. • Plants are growing well in these Technosols, especially in the presence of compost. • After four years, macrofauna and vegetation diversity is comparable to natural soils. • Carbon can be stored in Technosols, especially in the absence of compost addition.