Ecological and hydrological performance of green roofs established by topsoil translocation of local meadow communities

Green roofs are increasingly adopted as nature-based infrastructure for mitigating urban stormwater runoff, yet few studies have evaluated systems established using topsoil translocation of local meadow plant communities. This study provides one of the first empirical assessments of both ecological and hydrological performance of green roofs established by topsoil translocation of local meadow communities. This study evaluated (1) the establishment and seasonal development of translocated meadow vegetation over one growing season under irrigated and non-irrigated conditions, (2) the extent to which rooftop plant communities reproduced the plant species composition of their original source habitats, and (3) the stormwater runoff performance of different community compositions under simulated rainfall. Local communities in Chiba, Japan, established successfully on the roof when supplemental irrigation was provided, showing high fidelity to source vegetation in irrigated plots (>90% species overlap), whereas non-irrigated plots experienced strong drought filtering. Under heavy rainfall (50 mm h⁻¹), vegetated trays significantly reduced runoff volume and delayed runoff whereas vegetation had limited influence under light rainfall (10 mm h⁻¹). Dominant tall species, particularly Artemisia indica and Miscanthus sinensis , played a key functional role in canopy interception and water retention. Our findings demonstrate that intact meadow communities established by topsoil translocation can enhance ecological fidelity and reduce stormwater runoff, indicating potential multifunctional benefits of this approach on green roofs.