Elizabeth Daigneau is GOVERNING's managing editor.E-mail: email@example.com
"Not all green spaces are green,” says Michael C. Farmer, an associate professor of agricultural and applied economics at Texas Tech University. It’s his way of saying that not all green spaces are created equal. But figuring out what makes one space greener than another can be difficult because “land use decisions operate under short timelines and modest budgets.”
Four years ago, Farmer and his Texas Tech colleagues Mark C. Wallace and Michael Shiroya began looking for a way to differentiate between green spaces, a tool that would enable officials to easily pinpoint which landscapes have richer ecosystems, or simply put, which green spaces are more green. So they started counting birds.
What the researchers found was that the number of birds on a given plot of land -- and the number of diverse species -- not only indicated eco-diversity, it also related to property values. In a survey published late last year, Farmer and his colleagues collected information on home sales in Lubbock, Texas, in 2008 and 2009, and then conducted bird counts near the recently sold properties. The presence of “less ubiquitous” species, such as blue jays, mourning doves and western kingbirds, correlated with higher home prices. Just a single additional species could add about $32,000 to a home’s value.
The study also showed that a more diverse avian population meant a more diverse tree canopy. Think of the children’s song, “Head, Shoulders, Knees and Toes,” Farmer says. “If you have all those height variations, you have more diversity.”
While the findings may not surprise ecologists -- who have long found that a varied, layered landscape encourages diversity in urban wildlife -- the “deliberately simple and inexpensive tool” designed by Farmer, Wallace and Shiroya might. “If the ecologist, economist and planner seek ecological economic outcomes, [then] the analysis here points to … where landscape design contributes to ecological outcomes and to economic development,” the three wrote in the study. In other words, the tool identifies “even stronger gains to housing values, environmental footprint and urban wildlife that might otherwise go unnoticed in a quick-paced development cycle.”
For practical purposes, “this variable gives a little more heft to urban ecologists’ observations,” says Farmer. Planners consult urban ecologists all the time. If planners want to know what the value of a creek is to a new development, for example, “urban ecologists can go out there over the course of a few weeks and get a good sense,” he says.
The value of the variable goes beyond home values and economic development. Yes, higher home values mean higher property tax revenues and even sales taxes, but bird diversity and diverse tree canopies are also valuable to public green spaces, such as local parks. The tool suggests a new way to think about building and managing urban parks, and could even be useful to landscape architects and forest ecologists. “If you create a park that isn’t worth anything, you just add expense,” Farmer says. “If you do it right, you add more value.”
Ultimately, the model has the potential to help economists, planners and ecologists build better urban neighborhoods, ones that “pollute less and increase healthy lifestyles,” Farmer says.