The hypothesis of urban ecological homogenization states that urban ecosystems are ecologically more similar to other urban ecosystems in geographically disparate regions than to their own surrounding native ecosystems. Increasing urban tree cover for the provision of essential ecosystem services like temperature regulation, carbon sequestration, and air pollution mitigation is a common component of urban planning across the US. Yet, this approach may not be sustainable in arid cities like Phoenix, AZ. To what extent have we distanced our urban ecosystems from encompassing native ecosystems? This study examines tree, shrub, herbaceous, and barren land cover types in communities featured in the online EnviroAtlas decision tool, compared to surrounding ecoregions defined by Omernik. Urban-ecoregion similarity is explored between current land cover within the urban boundary and a hypothetical “natural” state within the ecoregion. Definition of a hypothetical “natural” state is based on a range of values from the National Land Cover Database (accounting for anthropogenic influence), LANDFIRE products of existing and potential vegetation, and Kuchler’s potential natural vegetation (without human impact).
Preliminary findings confirm surplus of tree and herbaceous cover and deficit of shrub cover in a desert ecoregion community, as well as surplus of herbaceous cover and deficit of tree cover in forest ecoregion communities. With EnviroAtlas, results of varying similarity to reference ecoregion land cover will be mapped at the Census Block Group (CBG) level to inform decision-makers. Ranked CBGs in communities across the US illustrate geographic variability in tree, shrub, and herbaceous cover compared to surrounding ecoregions. Urban planners may now consider strategies to move urban systems closer to their surrounding native ecosystems to increase ecosystem services, like temperature regulation, while conserving soil and water resources.
This abstract has been reviewed and approved by the U.S. Environmental Protection Agency. Its contents do not necessarily reflect the views and policies of the Agency.