Assessing Green Roof Contributions to Tree Canopy Ecosystem Services and Connectivity in a Highly Urbanized Area

Abstract

Ecosystem services refer to the benefits provided to humans by the natural environment and healthy ecosystems. Green roofs can be used to enhance ecosystem services, which are reduced by urbanization. Moreover, green roofs can improve biodiversity by connecting green spaces. Therefore, it is necessary to examine the multi-dimensional contributions of green roofs to urban ecosystems. To this end, we used i-Tree Canopy to identify changes in land cover and tree canopy ecosystem services from 2003 to 2021 in Suwon City, Republic of Korea. Next, we simulated improved ecosystem service effects of tree canopies by green roofs. Graph theory was also used to analyze connectivity improvement at local and landscape scales. Tree area was found to decrease from 2003 to 2012, alongside the corresponding ecosystem services, which then showed a tendency to increase from 2012 to 2021. The tree area was expected to increase further in the green roof scenario than in 2003. Green roofs were found to improve tree canopy connectivity at the landscape scale more than the local scale, by acting as stepping stones in connecting fragmented forests and trees. Areas with improved connectivity at both scales should be prioritized for green roof development. These results will aid in the strategic planning of urban green infrastructure and provide support for decision-making processes to improve ecosystem services and connectivity using green roofs.