As urban areas continue to expand, remnant forests in metropolitan areas will be exposed to a novel environment with higher temperatures, elevated CO2, greater fragmentation, higher light availability and pollution. We rely on the ecosystem services that urban forests provide such as carbon storage, recreation, and pollution mitigation but, urban forests are often overlooked as an important ecological system. Information on urban trees is critical as they will influence the composition and function of future forests that will form as urban environments expand. If the stress of the urban environment only allows for specific species to persist, then urban forests may differ in their diversity and forest community types compared to rural forests. We asked whether the community structure differed across and urban to rural gradient in Cleveland, Ohio, USA. To test for community differences, we used a stratified random sampling design to select 60 forested sites. We characterized tree species composition and basal area in 20 X 25-meter plots.
Results/Conclusions
NMDS visualization and PERMANOVA tests suggest that the tree community composition of urban forests significantly differ from those of rural areas (p < 0.001). While many species existed across the urban-rural gradient, they differed significantly in their presence in the community. For example, white oak basal area was approximately 4 times higher in rural tree communities compared to urban communities. Additionally, urban sites tended to have a higher diversity of tree species. These differences in diversity and forest composition are likely due to a combination of anthropogenic choice of protected areas, land use history leading to variable age of forests, and urban environmental stress. Future work will analyze the functional traits of tree communities at these locations to better understand how urbanization will affect the structure and function of remnant forests in the future.