“Pocket parks” and other small green spaces can increase the number of bird species in patches of the city, according to a new study in Landscape and Urban Planning.

Conservationists are wrestling with the challenge of preserving wildlife in ever-expanding urban areas. Large parks make up the bulk of green space in cities, but community organizations also have been creating miniature parks in vacant lots and adding plants to yards and streets.

To find out how much these modest green spaces contributed to urban biodiversity, the researchers examined 12 greening projects in Boston, which ranged from planting trees along the street to setting up community gardens. Volunteers surveyed the birds at each site for about a week and a half in the summers of 2010 and 2011, as well as at nearby random sites and at large parks.

Not surprisingly, the big parks supported the richest set of birds. At eight of the small green spaces, the number of bird species surpassed the number at corresponding random sites. Sites that were larger and contained more trees with hollows tended to have more species. “Even small increases of a few hundred square meters were associated with an increase in bird richness,” the authors note.

Mini-parks will boost biodiversity the most if they’re linked to existing parks, the team says. But many of these community projects take place in neighborhoods where green space is sparse. So organizers “may have to choose between prioritizing biodiversity and environmental justice goals,” the researchers write. Roberta Kwok | 2 April 2013

Source: Strohbach, M.W., S.B. Lerman, and P.S. Warren. 2013. Are small greening areas enhancing bird diversity? Insights from community-driven greening projects in Boston. Landscape and Urban Planning doi: 10.1016/j.landurbplan.2013.02.007.

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