Urban vegetational change as an indicator of demographic trends in cities: The case of Detroit

Urban vegetation impinges upon the physical environment by positively enhancing the microclimate and air and water quality. On the other hand, changes to the physical environment as well as the socioeconomic conditions of urban dwellers affect the health of urban vegetation and species abundance and diversity. This two-way vegetation-environment dynamism makes urban vegetation an ideal meter to gauge the environmental health of cities. Although studies utilizing such a proposition exist with reference to the physical environment, the usefulness of vegetation in monitoring urban social change has received very little attention. In this study the author seeks to find whether changes in urban vegetation can be linked to urban social changes by using Detroit as a case study. Demographic trends in Detroit are analyzed in light of the increasing greenness in the city detected by recent satellite images. Robust relationships between greenness change and demographic factors associated with urban decay (population decline, an increase in poverty level, and an increase in vacant units) are found. Models built with a remotely sensed greenness change index and urban decay variables appear to be free of any serious bias. Tests for the validity of such models are also successful. It is concluded that vegetation trends could be used as indicators of urban socioeconomic changes. A vegetation-based urban environmental quality index could therefore be developed to monitor physical and social changes in cities.