Human-managed and occupied ecosystems may contain analogous structures or functions to naturally occurring habitats, either spontaneously or by design. Understanding how communities of organisms assemble and use these built spaces provides a key opportunity to understand, and potentially shape, the ecosystem functions and services delivered in human-dominated landscapes. For example, green roofs are a type of living architecture in which plants are intentionally grown on top of a human-built structure and can be functionally similar to some local thin-soil environments, providing an opportunity to 1) understand the environmental controls on communities arising in these habitats and 2) design green roofs to incorporate desirable features of similar natural systems. Our work focuses on characterizing insect communities and vegetation in natural thin-soil environments and green roofs to examine and quantify the services those insects provide (i.e. pollination, pest control, and decomposition). Insects are passively trapped using sticky cards, bee bowls and ramp traps. Vegetation is sampled using a randomly placed meter-squared quadrat. We predict that green roofs will function similarly to natural thin-soil environments, but diversity patterns in higher trophic levels, both from a function and identity standpoint, will be driven by identity of planted and colonizing primary producers.
Results/Conclusions
We conducted our study in a north-south transect in the Great Lakes Basin, centering on the Cleveland metropolitan area and extending into southeast Ohio and Ontario, Canada. There were 9 natural sites and 4 green roof sites (2 with native plants, 2 with non-native plants) in the study, with all green roofs located in the Cleveland area. Over 25,000 insect specimens have been identified to date. A larger number of individuals were found at the natural sites than the green roof sites (17103 and 8384, respectively). This holds true when comparing the green roofs to their local natural sites (8924). The natural sites contained more taxonomic groups identified than the green roof sites (48 and 37, respectively). Both types of sites can support insects that provide the services of pollination, pest control, and decomposition, but insect communities and relative abundance of functional groups varied between sites. Characterizing the function and impact of insect services in natural and urban ecosystems is critical to supporting conservation decision-making in these human-managed ecosystems. Findings will be useful in informing the design of more valuable green roofs, or other structurally analogous urban spaces, with improved ecosystem service provision.