Green roofs as constructed ecosystems : native plant performance and insect diversity

Abstract

Green roofs are increasing substantially in urban areas because they contribute to numerous environmental, social and economic benefits while occupying unused city space. This study has two objectives: to quantify the performance of native plants on extensive green roofs so to improve plant selection and design; and to compare insect diversity and composition of green roofs with that of adjacent ground level urban habitat which is critical in understanding green roof ecology. Several plant species had optimal survival and cover, as well as improved performance over growing medium only controls, although sizable differences existed within and between life form groups. Green roof insect diversity was similar to that of ground level urban habitat and many unique species were identified. Interestingly, plant richness had a sizable effect on insect richness. Taken together, these experiments demonstrate that plant selection is important in both improving green roof technical performance and creating urban habitat.