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Urban areas offer surprisingly useful ‘stepping stones’ for at-risk species

After a recent global assessment of biodiversity found that one million species are now threatened with extinction due to human activities, a new study suggests that urban environments could serve as a potential conservation lifeline in the coming years.

Urban areas, densely populated with people and lacking in green space, are considered “low-quality habits.” These habitats may offer some sources of food for pollinators but are not suitable for population growth.

Researchers from Tufts University, the University of Liverpool, Washington State University and the University of Iowa conducted a study to assess the viability of low-quality habitats in aiding conservation efforts.  

The study, published in the journal Ecology, shows that urban areas are much more useful for pollinators than previously realized and that many species take advantage of low-quality habitats in order to reach high-quality habitats quickly.

It’s in high-quality environments that species that thrive and reproduce.

The researchers reviewed data from 70 studies involving 78 species in total and found that 73 percent of the time, the animals moved quickly and efficiently through low-quality habitats to get to a high-quality area.

This allowed for rapid range expansion evidenced by the Baltimore checkerspot butterfly, which was able to reach suitable habitats quickest in landscapes made up of 85 percent unstable habitat and 15 percent high-quality habits.

“At landscape scales, 15% high-quality habitat is still more than currently exists in most ecosystems,” said Elizabeth Crone, the lead author of the study. “Nonetheless, our findings point to the potential of using suburban and even urban greenspace as underappreciated areas that could facilitate range shifts, if green spaces such as lawns were converted to native plant gardens, which have high conservation potential for insects and other wildlife species.”

The results of the study show that urban landscapes are useful to population growth and biodiversity.

“This could offer a new perspective of flexibility for landscape planners: they needn’t worry if they can’t create unbroken tracts of high-quality wildlife habitat, instead they can create strategic ‘stepping stones’ in urban and agricultural areas,” said Jenny Hodgson, a co-author of the study.

“However, the stepping stones need to provide resources for breeding, not just temporary food resources.”

By Kay Vandette, Staff Writer

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Image Credit: Leone Brown, Tufts University

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