Effects of Green Roof Features, Management Practices, and Age on Decomposition Rates, Carbon Storage, and Substrate Composition

(1) Green infrastructure, such as green roofs, is emerging as an important way to improve environmental quality and protect crucial ecosystem services in urban areas across the globe. However, limited data exist on the specific ecosystem services provided by green roofs, particularly regarding how these services evolve over time and under varying management regimes. (2) This study examines how management, age and other variables influence some key substrate features, such as decomposition and carbon storage, that drive ecosystem services provided by green roofs in 13 urban locations across three states in the Southeastern United States. Data were collected over 4 months from March to June 2024, using the teabag index and substrate nutrient sampling. (3) We identified several significant effects of green roof management, age and other variables on key drivers of ecosystem services, including decomposition rate, carbon storage, and nutrient composition. (4) Specifically, intensive management practices were associated with lower substrate decomposition rates, while irrigation, substrate additions and elevation had significant positive impacts on decomposition rates, the stabilization factor (carbon storage), organic matter and other nutrient levels. Overall, intensive management, which often involves higher costs, did not consistently enhance ecosystem service delivery and was associated with slight reductions in service provisions. Although further work is needed, this study is among few that have examined green roofs substrates in a statistically rigorous way.