Ecology of foreclosure: Post-recession vegetation characteristics of urban landscapes

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Often, we think of cities as designed ecosystems, where people are the dominant driving force and manage everything – from the structure of the landscape to the materials it’s composed of, and from the placement of key resources to how those resources are allocated. But what happens when we can no longer allocate scarce resources to the maintenance of our urban landscapes? Do abandoned yards become overrun with noxious plants? Are valuable ecosystem services lost in a reshuffling from top-down to bottom-up drivers? Are some types of residential landscapes and some neighborhoods more vulnerable to economic stressors than others? The recent housing bubble and subsequent recession provided a unique opportunity to examine what happens ecologically when a city undergoes an economic disturbance. It is well-understood how ecological processes shape plant communities in ‘natural’ systems, but this research is unique by demonstrating how an economic disturbance like the Great Recession can shape urban landscapes and plant community dynamics.

In arid Phoenix, different landscape aesthetics require varying inputs of water, and homeowners’ preferences are reflected in their choice of landscape. We don’t know how urban landscapes, especially in arid cities, respond to economic stress. We don’t understand how high a priority landscape maintenance is during times of economic crisis. Many residential lots in the Phoenix Metropolitan Area were foreclosed on and remained unoccupied after the Great Recession. On foreclosed lots, people abandoned their role as designer and manager, leaving bottom-up forces to shape and restructure the system.

In a preliminary study using CAP LTER data, I observed directional changes in plant community diversity and composition across survey years that bracketed the housing bubble peak and subsequent bust. In a pre-recession survey, despite above-average regional precipitation, residential plant species richness and heterogeneity were lower than in a 2010 post-recession survey. Motivated by this preliminary study, I revisited 75 foreclosed houses last surveyed in 2010. This sidewalk survey of urban residential sites examined coarse vegetation patterns for a signal of economic disturbance using a finer temporal scale than the semi-decadal sampling schema the CAP LTER survey captured. My sidewalk survey confirmed expectations based on the preliminary study - that introduced annuals were a sizeable, visible component of the vegetation present at foreclosed houses and in many adjacent yards. This study will present preliminary results of plant community diversity and compositional change alongside a photo essay of residential neighborhoods impacted by the Great Recession.