Which produces less-impacting patterns of urban growth, targeted or general public policies?

Background/Question/Methods

Consumption of land for use in cities and urban settings is a major force altering the environment. A measure of how efficient different land use policies or plans are, is how much open space they leave for other purposes, whether natural or for human use. Here we examine the effect of five alternative policies on land consumption in California, USA. The study used an urban growth model, UPlan, to portray patterns of new urban growth by 2050. The policies represent three scenarios that do not incorporate climate risk: Business-As-Usual, Compact-New-Growth, and Infill; and two scenarios that mediate future climate risks: Landscape-Connectivity for projected range shifts of plant species, and Least-Impacted-Agricultural-Lands. The resulting urban spatial patterns were used to assess whether target-specific public policies, such as agricultural protection or connectivity, or generalized guidelines for new growth better optimize competing demands for land use for both development and conservation goals, i.e. were more effective.

Results/Conclusions

This paper demonstrates an integration between two major areas of interest – impact assessment of climate change and from urban expansion. This type of cross-cutting analysis is needed to help guide public policy. It is also a promising area of research for landscape ecologists. While target-specific scenarios were sometimes more effective for a single objective, Infill, which places much new growth inside the boundaries of existing urban areas, was the most effective overall strategy for preserving open space for other uses. The results suggest that combining Infill objectives with other open space goals will produce better conservation goals for those objectives than merely directing growth away from landscape elements of conservation interest. A need identified from this study is a calibration curve, which identifies how much additional open space could be preserved when different percentages of new urban growth are directed into Infill. Recognition of the multiple needs for open space including ecosystem services, biodiversity preservation, food security, and mental health would help ecologists gain more traction in the day to day world of planners and society. The measure of open space, for any purpose, used here is representative of a simple way this broader perspective can be achieved.