Urban Greening Impacts on Biodiversity and Environmental Justice

Many city governments across the US are working to increase their green spaces in an effort to reduce climate impacts, support biodiversity, and make cities more livable. Shannon LaDeau is involved in several efforts to better define and understand what biodiversity means in urban environments, and to evaluate the impacts of urban greening, including unanticipated side effects.

LaDeau is investigating the processes by which canopy vegetation is distributed throughout cities, and how this vegetation impacts local biodiversity and environmental justice. Prior work has demonstrated the importance of large, old trees in providing vegetation-based ecosystem services. Their distribution across the urban landscape reflects decades of human decision-making and investment. Large, old trees are often absent in neighborhoods where property values have been persistently devalued, resulting in a wealth-gap in equitable distribution of canopy cover. Effects are felt to this day, with recent work showing canopy cover increases are greatest in locations where these old trees persist. Additionally, this work has shown that in Baltimore, the biodiversity benefits of street trees are also concentrated in wealthier neighborhoods, and that non-native street trees are more common in low income neighborhoods across the City.

The uneven distribution of urban vegetation can also influence important health outcomes. For example, LaDeau and her colleagues have found that less affluent areas of Baltimore have more and larger mosquitoes, linked in part with unmanaged vegetation, making these neighborhoods more vulnerable to mosquito-borne diseases.

When Baltimore residents were given digital cameras to document environmental amenities and disamenities in their local neighborhoods, LaDeau and colleagues found that unmanaged vegetation was a stressor that often limited local support for future greening efforts. Larger survey tools also highlighted linkages between mosquito and rodent exposure with perceptions of vegetation as a top environmental problem.

In an upcoming project, LaDeau plans to examine what urban biodiversity means to different groups of people, and what it may take to produce equitable and just urban conservation in a climate-changed future.