A Study in the Comparative Viability of Green Roofs Constructed Using Native Accent Species Relative to Green Roofs Using Sedum Accent Species: A First Step Toward the Potential Development of Green Roofs as a Tool for Creating a Transition Zone Between Native and Urban Ecosystems

Abstract

Modern urban development over the last 200 years has led to the construction of cities which create severe issues for native ecology, human health, and the safety of both people and property. Among these issues are the urban heat island effect, flash flooding due to paving of stormwater runoff paths, and urban ecosystems acting as disruptions to surrounding native ecosystems. Green roofs help mitigate flash flooding and the urban heat island effect, and they have the potential to be developed into a tool for integrating urban and native ecology. Because green roofs can have a lifespan of thirty years or more and due the high initial set up cost of a full green roof, this project functions as a proof of concept for a long-term study that might advance the development of such a tool, while minimizing the loss if one or more of the green roof designs is completely non-viable. There were also plans to assess the impact the accent communities had on ecosystem services, however disruption due to Covid-19 restrictions made this impossible. This project found that green roofs planted with a community of experimental native accent species established themselves successfully to the same degree as those planted either with proven native accent species or sedum accent species, and the accent community present had no bearing on the establishment of the sedum groundcover communities, with neither Blocks B or C showing statistically significant change in vegetation coverage year over year that could be attributed to either irrigation treatment or accent community. Furthermore, after one year, neither irrigation treatment nor accent community had a significant impact on the degree of vegetation cover. Based on these results, the green roof designs used in this project are viable enough at least for use in a long-term study to test the ability of the design to actually facilitate the integration of urban and native ecosystems without the risk of early green roof failure.