Urban Green Space Enables Unexpected Biodiversity

A sprawling concrete jungle with millions of people might not readily appear as a place full of natural biodiversity, especially compared to the natural lands that have been cemented over to create the cities. But new research involving 147 cities has found that a surprisingly large number of plant and animal species persists and, in some cases, flourish in urban environments.

Researchers from the National Center for Ecological Analysis and Synthesis (NCEAS) report that cities are not the wastelands of biodiversity that they are sometimes considered to be.

Cities, the researchers found, host a mix of species that reflect the unique biotic heritage of their geographic location.

The research, which was funded by the National Science Foundation, is published in Proceedings B, a journal of the Royal Society of Biological Sciences.

"While urbanization has caused cities to lose large numbers of plants and animals, the good news is that cities still retain endemic native species, which opens the door for new policies on regional and global biodiversity conservation," said lead author Myla F. J. Aronson.

Aronson and her colleagues say that green space in cities is crucial to urban biodiversity because those areas are where many native and migrating species take refuge. Within a city's parks and other green spaces, threatened and endangered species can flourish, even as others disappear or decline, the researchers report.

Still, cities support 92 percent fewer birds and 75 percent fewer native plants than similar areas of undeveloped land.

"We do pay a steep price in biodiversity as urbanization expands," said study co-author Frank La Sorte, a research associate at the Cornell Lab of Ornithology. "But even though areas that have been urbanized have far fewer species, we found that those areas retain a unique regional flavor. That uniqueness is something that people can take pride in retaining and rebuilding."

The researchers recommend conserving urban green spaces in order to promote continued biodiversity.

 "It is true that cities have already lost a substantial proportion of their region's biodiversity," said Madhusudan Katti, a faculty member in the Department of Biology at California State University, Fresno. "This can be a cup half-full or half-empty scenario. If we act now and rethink the design of our urban landscapes, cities can play a major role in conserving the remaining native plant and animal species and help bring back more of them."