How Lizards Can Teach Planners About Designing Cities

Cities have long been understood to be human constructs; that is, its history of builders have bent nature to human’s needs. Coastlines were re-contoured for harbours or casinos. River-valleys were filled in for reservoirs or highways. Forests were replaced with houses or stadiums. The day’s logic dictated the need to shape the earth to provide humans with the goods needed for their survival (food, water, shelter and so on).

This anthropocentric view, however, is displaying disastrous consequences—from psychological disorders associated with a lack of exposure to nature, to flooded cities, to collapsed ecological processes that are needed to provide us with food, water, shelter, and so on.

Studies continue to push back against this view. We're advancing to recognize that the equation is not society and nature but rather society in nature, that how we plan cities is a way of organizing nature. Studying the needs of lizards is one way to parse this equation.

Authors in the journal Urban Ecosystems state that climate change will drive "half of the world’s lizard population to extinction." Exacerbating the collapse may be the warmer temperatures experienced in cities. Termed the urban heat island effect, this phenomenon occurs when the temperature in the city becomes higher than the surrounding rural areas. Reports indicate these temperatures can range from 1-3°C to as much as 12°C hotter.

Using a location in metropolitan Phoenix, the main objective of the study investigated "which landscaping styles and microhabitat variables can most effectively reduce the surface temperatures experienced by lizards." Exposed under the hot sun lizard activity time was restricted to a few hours, the authors said. "While heavily irrigated grass and shade trees allowed for continual activity during even the hottest days." Those areas under shade with increased humidity and access to a view of the sky explained the cooling effect needed for lizards to survive in the metropolitan climate.

This work continues to cast a bright light informing that planning cities for humans is not divorced from planning cities for nature; they are not mutually exclusive. For example, the research provides planners with scientifically-based work indicating a type of urban form that could mutually benefit humans and wildlife.

The ecologists warn that with continuing urbanization and climate change over the coming decades heat stress will continue to become an increasingly important facet of city living for humans, plants, and animals. The authors suggest that maintaining an existing diversity of landscaping styles necessary for the lizards parallels the ongoing mitigation strategy to lessen the urban heat island effect targeted at humans.

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