Study of vegetation to be used in urban regeneration to increase resilience

Urban areas are increasingly facing important challenges that can have serious consequences on people's health and well-being. Nature-based solutions can make a significant contribution to improving environmental quality and providing ecosystem services, consequently improving people's health and well-being. Building-integrated vegetation (BIVT), in particular green roofs (GRs), has seen a widespread increase in many cities; however, different urban climates make the implementation of low-maintenance, high-performing BIVT particularly challenging. Therefore, the study of vegetation to be used in GRs to increase urban resilience becomes crucial to improve their performance and sustainability. This research is focused on the study of vegetation to be used in GRs with the aim of providing experimental evidence to support their design, construction, and management. It has considered the use of native, low-maintenance forbs, the potential benefits of co-cultivating different species to strengthen GR’s resilience, the use of plants with both ornamental and medicinal properties in a multifunctional perspective, and novel, sustainable management protocols to reduce the use of chemicals. The research evaluated the performance of Trifolium repens, Melissa officinalis, and Hypericum perforatum on an experimental GR, comparing single-species vs. mixed-species cultivation, chemical fertilizers vs. mycorrhizal bio-stimulants, and the use of Trifolium repens as a catch crop and green manure vs conventional fertilization and bio-stimulants. Results showed that T. repens excelled in cover and biomass, being suitable for extensive GRs if properly managed. The results confirmed the possibility of using native medicinal plants in the design of low-maintenance GRs, obtaining good performances in terms of plant biomass and secondary metabolite production. The study also demonstrated the possibility of reducing the use of chemical fertilizers either by using mycorrhizal bio-stimulants, or by using nitrogen-fixing plants, such as T. repens, as catch crops and green manure, still obtaining good levels of coverage and biomass.