Municipalities worldwide are showing substantial interest in urban greening, defined here as the introduction or conservation of outdoor vegetation in cities. In many cases greening involves substantial tree planting, and across the United States cities have established ambitious canopy cover goals and major tree planting programs. Such is the case in Massachusetts, where the state initiated in 2014 the Greening the Gateway Cities (GGC) program, a tree planting initiative targeting 26 municipalities identified as "Gateway Cities," a term that describes struggling post-industrial cities which serve as a gateway to the regional economy. As a pilot, nearly 1,400 trees were planted in the City of Holyoke in 2014 (including about 550 public street trees), and in the next two years some 3,700 street trees were planted in other Gateway Cities. This tree planting activity raises important questions about potential effects on neighborhood satisfaction and human safety.
This study aims to assess longitudinal links between street tree vigor and neighborhood satisfaction and safety of recently planted urban trees. A "cohort" approach is especially relevant because trees are living organisms whose physical form changes substantially over time. Research on newly planted urban trees as a cohort across time is a relatively new line of scholarship that focuses primarily on tree survivorship and mortality; and to the best of our knowledge, no previous research has studied links between neighborhood satisfaction and safety, and urban tree plantings, as a longitudinal cohort.
Neighborhood satisfaction and human safety are multidimensional phenomena that can be studied through a combination of objective and self-reported data. Four study areas will be determined based on a matrix of street tree health and recorded incidence of crime, which is one dimension of neighborhood satisfaction and safety. Residents on these streets will be incentivized to complete a neighborhood satisfaction survey which will include a prompt to communicate the places and features they perceive as safe/unsafe. In addition, urban design features and landscape characteristics will be documented for each study area. This combined set of data inventory and analysis will be conducted in the first year of the study (2018) and repeated in 2021. The data will be spatially and statistically analyzed to understand if street tree health and/ or changes in tree size/morphology contribute to neighborhood satisfaction and safety outcomes over time. This, in turn, may yield important insights about urban tree planting and management practice.
The need for this research is of growing importance as thousands of trees are being planted in cities every year in the United States. But it is unclear if municipalities have the institutional capacity to adequately manage this influx of new green infrastructure. The long-term implications of this tree planting activity upon neighborhood satisfaction and safety are also not
clear. This is particularly important in neighborhoods of low socioeconomic status where residents rely on walking as a mode of transportation, and where neighborhood satisfaction and crime may be especially impactful. Results from this research may inform current and future urban tree planting and management programs and contribute to safer streetscape environments.