How cities could help protect species threatened by climate change

Posted on Tuesday, May 14, 2019

Field of native flowers.

It might seem counterintuitive, but if cities and towns were properly designed, they could help species face the threat posed by climate change. According to a new study published in Ecology, animals move faster through “low-quality habitat” than through “high-quality habitat.” This aspect of animal behaviour could radically change the way we analyze how species move through the environment. It may also give us the tools we need to manage landscapes in a way that enhances the protection of insects and other wildlife.

The study, led by Elizabeth Crone, a professor of biology at Tufts University, and researchers from University of Liverpool, Washington State University and the University of Ottawa, provides a framework for definitive action to help preserve many species at risk. For urban and suburban landscapes to help expand the range of species, a specific balance needs to be struck between low and high-quality habitat: when a minimum standard is met, urban green spaces could in fact become an advantageous conduit for migration.

Urban landscapes as a whole will always be low-quality habitat, but if a percentage of them was converted into high-quality habitat, if simple lawns became native plant gardens, the desired balance would be met.

Using data from 78 species in 70 different studies, the research shows that in 73% of cases, animals moved faster through low-quality habitat. The team then employed mathematical models to calculate rates of range expansion across a variety of landscapes for an exemplar species -- the Baltimore checkerspot butterfly. Results showed the range expansion was fastest through landscapes composed of around 15% high-quality habitat and 85% low-quality habitat.

The reason behind these findings is quite simple: when animals find themselves in an inhospitable area, they tend to make longer and straighter movements. As long as they do not die in low-quality habitats, their journey toward the next high-quality habitat will tend to be quicker.

“We have the opportunity to tap into the conservation potential of suburban and urban green spaces,” said University of Ottawa’s Frithjof Lutscher, who was part of the research team. “Designers of city and suburban environments need to think differently and change their approach: if they commit only 15% of the landscape to high-quality habitat, they would create strategic ‘stepping stones’ for animals and do their part in preserving species threatened by climate change. While most suburban and urban landscapes currently have less than 15% high-quality habitat, we can strive to achieve it. This is a realistic and achievable objective.”

While most studies about biodiversity conservation have focused on documenting the patterns of species habitat and migration, this research focused on the mechanisms behind these patterns, therefore offering new and fresh insights to the field.

In light of the recent UN report indicating that 1 million species are threatened with extinction, this study and its findings give us hope that we could do our part to avoid the worst scenarios.


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