Urban Forestry

Turning Over a New Leaf

As cities grow larger and denser, the forests within their boundaries become increasingly important. Urban forests provide benefits such as increased air quality, heat island reduction, and recreation. However, planting trees is time-consuming and expensive, thus researchers are motivated to  focus on finding ways to make these urban forests self-sustaining. A recent Yale study has shed light on how to best treat and understand these critical forests.

The study analyzed data from research plots in Queens, New York that test three treatment methods: compost, nurse shrubs, and tree species composition (two-species versus six-species). While the nurse shrub and compost treatments individually did not facilitate the establishment of woody plants, combining the nurse shrub treatment with compost or six-species composition) treatments increased establishment by 47 and 156 percent, respectively. “This suggests that there are interesting interactions between treatments and that effective management strategies may require a suite of complementary treatments rather than relying on independent interventions,” said Danica Doroski, doctoral student in the Yale School of Forestry and Environmental Studies and first author of the paper. The study demonstrated that a combination of treatment methods, along with greater preexisting canopy cover, may hold the key to self-sustaining urban forests.

Doroski emphasized that natural processes occurring in urban forests make them more comparable to rural forests than landscaped parks—implying that tools and theories from classical forestry could be adapted and applied to urban settings to enhance our understanding. Doroski and her team intend to continue investigating management methods that promote self-sustaining urban forests and realize the multifaceted benefits they can bring to cities.