“…Urbanization causes profound impacts on ecosystem functioning (Pickett et al, 2011) but the consequences for urban soil ecosystem processes are not well documented (De Kimpe and Morel, 2000;Pouyat et al, 2010) despite their importance in the delivery of ecosystem services (Morel, Chenu, & Lorenz, 2015). Urban soils can be highly heterogeneous and are mainly affected by human activities (Morel et al, 2015). The soils in urban parks contain a significant amount of recently excavated earth from deep soil horizons and other man made materials such as bricks or crushed stones (used as backfill) (IUSS Working Group WRB, 2006).…”