Plant diversity on green roofs: A review of the ecological benefits, challenges, and best management practices

Abstract

Green roofs are promoted as a nature-based approach to mitigate various environmental issues and provide a variety of ecosystem services. However, establishing and maintaining plants on green roofs can indeed be challenging with unclear net benefits. This review explores plant diversity integration on extensive green roofs, emphasizing its ecological benefits, management challenges, and best practices to increase effectiveness and reduce costs. We highlight the global importance of diversity on green roofs as a nature-based solution to address some climate change challenges, demonstrating how this approach can mimic natural ecosystems, thereby enhancing ecological functioning and ecosystem services. We stress the importance of selecting plant species with appropriate adaptations while considering their potential limitations in providing various services. To optimize multiple benefits, we recommend a diverse mix of species with complementary resource utilization; because green roofs are harsh (i.e., shallow media, drought, exposure to sun and wind), and some species will not be suitable (e.g., species with deep roots adapted to meadows). We discuss the role of intermittent irrigation and other methods to promote coexistence. Furthermore, we underscore the significance of strategic species selection and the unexplored potential for different measures of biodiversity, particularly phylogenetic and functional diversity. The findings from this review demonstrate that further exploration in this area can guide sustainable urban landscapes.