Optimizing green roofs in the Netherlands by analysing the effect of soil moisture and nutrient availability on its flowering period

The continuous increase of the global human population living in cities has significantly impacted various aspects of nature and climate worldwide, affecting the local green space and its biodiversity. One initiative to promote urban biodiversity and its flora and fauna is the application of green roofs. However, the optimal design of these green roofs is currently uncertain, as it strongly depends on local environmental conditions. This research investigates the effect of water- and nutrient availability on the success of green roofs in the Netherlands, utilizing an adapted, experimental design of a green roof. Mineral wool was used as a water retention layer and compost was used to increase nutrient availability. The results indicate that adding mineral wool significantly affects the number of flowers, seeds and the total number of plant species. This applies to the planted species, as well as spontaneously growing species. The addition of compost, to increase nutrient availability, did not significantly affect these parameters of plant growth. This research shows that this adapted design aiming to improve soil moisture is crucial in stimulating the urban green space and its biodiversity in environments in the Netherlands. Besides, this research evaluates the results for the current state of green roofs (management) in urban areas and future possibilities and research recommendations.