Linked spatial and temporal success of urban growth boundaries to preserve ecosystem services

Abstract

Urban expansion and sprawl lead to loss of green space. This has the potential to degrade natural capital and associated ecosystem services. Urban growth boundaries (UGBs) are a planning tool to delineate where growth may or may not occur as a strategy to protect green and open space. However, how these policies impact ecosystem services is unknown, particularly across multiple years. Here we compare pairs of cities: one of which has a UGB and one that does not. Specifically, we analyzed the following city pairs: (1) Lexington, KY: Huntsville, AL and (2) Portland, OR: Denver, CO. We modeled the ecosystem services provided to each city, quantifying carbon storage, pollinator abundance, urban flood risk, and urban cooling. Our results show that UGBs succeed in preserving the ecosystem services, over time, at a higher and more predictable rate than cities that do not have a UGB. Change over time highlights the effectiveness of UGBs in preserving ecosystem services overall and concentrating loss of ecosystem service delivery within highly urbanized areas. We discuss how the data necessitates analyzing spatial and temporal trends together to incorporate starting values of ecosystem service function for comparison between case studies. Natural capital and its associated ecosystem services should be key criteria for assessing policies for urban planning and used to further implement laws and policies to enhance environmental and human health within urban areas.