Assessing the value of native and exotic trees across the inner city and suburban forest of Cleveland, OH

The urban forest represents a valuable resource to urban residents and a critical building block for future sustainable development. Trees provide numerous ecosystem services including removal and storage of CO₂ and mitigation of the heat island effect, while also supporting a high biodiversity of animal fauna including arthropods. Our goal was to test the hypothesis that exotic tree species are dominant within the urban forest and are responsible for provisioning the majority of ecosystem services within inner-city communities. We began by compiling inventories of the trees found across three different urban habitat types: 1) inner-city vacant lots, 2) inner-city residential properties, and 3) suburban residential properties. Using the software application i-Tree Eco, we estimated urban forest structure and composition across these habitats and quantified the value of the ecosystem services provided by each habitat’s unique forest assemblage. Vacant lots supported the greatest abundance of trees, while no difference existed between the inner-city and suburban residential habitats. Exotic species were common across all habitats, however the inner-city habitats had significantly more self-seeded, “weedy” tree species such as white mulberry (Morus alba L.) and tree of heaven (Ailanthus altissima Mill.). The forest assemblage found on vacant lots provided substantial ecosystem services, indicating the habitat’s value as pockets of greenspace within the urban matrix. Future work will assess how the dominant exotic tree species found in vacant lot habitats differ in their ability to support arthropod biodiversity when compared with native congeners.