Wind-Driven Drought Stress in Green Roof Vegetation: Implications for Urban Resilience

Green roofs are increasingly recognized as nature-based solutions that enhance urban resilience by supporting biodiversity, regulating microclimates, and mitigating stormwater runoff. However, their performance—particularly in extensive, lightweight systems—is often constrained by drought stress, which limits plant survival and ecosystem functioning under climate change. While substrate composition has been widely investigated in this context, the role of wind as a co-driver of drought impacts remains poorly understood. In this study, we examined how moderate wind interacts with substrate properties to shape drought responses in green roof vegetation. Using three non-succulent species (Plantago maritima, Pilosella officinarum, and Festuca rubra), we quantified substrate and plant water balance, physiological performance, wilting dynamics, and survival under prolonged drought conditions. Our results demonstrate that wind significantly accelerates drought effects—regardless of species or substrate—by intensifying substrate desiccation, with critical moisture thresholds reached at 6–8%. While wind alone did not impair plant performance under well-watered conditions, its interaction with drought markedly reduced survival time and increased physiological stress. Although general response patterns were consistent across species, subtle interspecific differences indicate that plant selection for green roofs should account for combined drought and wind exposure. These findings highlight wind as an overlooked but critical factor in the design and evaluation of resilient green roof systems and potentially contribute to a more comprehensive understanding of vegetation performance in urban nature-based solutions under climate stress.