Less clustering and more naturally occurring trees could reduce pest and pathogens in urban forests
A new study in eLife finds excessive clustering of tree species and over introduction of nonnative species may make urban forests more vulnerable to pests and disease.
Co-lead authors Dakota E. McCoy (‘21) and Benjamin Goulet-Scott (‘22) assembled a dataset of more than five million street trees living in 63 of the largest cities in the United States. They then analyzed the data through an ecological lens. They found that there is a wide range in the diversity of street tree communities across cities and that these communities vary greatly in the proportion of naturally occurring versus introduced species, with some relationship to local climate. The study further showed that street trees are clustered by species in the majority of cities, likely making them more vulnerable to pest and pathogen outbreaks.
McCoy and Goulet-Scott began working on the study while Ph.D. candidates in OEB. Their goal was to recognize that cities are ecosystems and that street trees represent a large and foundational component of these urban ecosystems. As students, McCoy and Goulet-Scott shared an interest in environmentalism and in work that informed concrete policy or legal actions with positive environmental impact. Part of the work on this study was performed as they founded the GSAS Environmental Action Team at Harvard. With their dissertation work on hold due to COVID, they developed a full research project and recruited and hired one Harvard undergraduate through the FDR Foundation and one undergraduate enrolled in the OEB REU summer program. In the course of their research McCoy and Goulet-Scott initiated a collaboration with the Biota of North America Program (BONAP) which provided crucial data for analyses.
The article is open access and available to municipal authorities who might not otherwise have access to academic journals, including the dozens of city foresters who shared their data with the researchers.