2017 | Kathleen Wolf, PhD, University of Washington
What is the economic value of having trees in cities and towns? There are widely used models for economic values concerning the environmental services of trees, such as air and water quality. Human health outcomes – including disease prevention, improved mental health, and better community cohesion – suggest additional economic returns, yet little is currently known about this potential. This project will extract research about the human health benefits specific to city trees and forests, synthesize the findings into a review publication, and conduct economic valuation using a benefits transfer approach. Nearly 40 years of research indicates the human health benefits gained from experiences of nearby nature in cities, and is summarized at the Green Cities: Good Health (GCGH) web site, hosted at the University of Washington. The article database that informs GCGH includes a subset of articles that focus on human health responses associated with city trees and urban forestry, and this peer-reviewed literature will become the basis for valuation strategies. This work is important as professionals who work in arboriculture, urban forestry, green infrastructure, landscape design and related fields are often challenged to justify the costs of tree planning, planting and management. The results of the focused economic analysis will be submitted for peer-reviewed publication, and translated to science delivery products, to include a results briefing, PowerPoint presentation, and urban forestry policy guidelines.
We need trees to sustain city residents and to improve community livability! This project, funded by TREE Fund had two goals –to understand the full range of health benefits provided by trees, and to calculate the economic consequences of those benefits. Additional support for the project was provided by the USDA Forest Service, Health Canada, Natural Resources Canada, Tree Canada, the University of Washington and the University of British Columbia (Canada).The project had three activities. The first was to conduct an academic literature review focusing on city trees and human health. The second was to convert the evidence to urban and community planning, that is, to propose how trees might be arranged within communities and neighborhoods to generate better health outcomes. The third activity was to translate the health benefits to economic value. The literature review generated a list of 201 studies about health benefits, sorted into three categories. Trees Reduce Harm, that is, they mitigate the conditions that compromise health, such as air pollution or extreme heat. They also Restore Capacities by improving mental and physical functioning. And they Build Capacity for health by facilitating the conditions that promote wellness, such as settings for physical activity and social interactions. All urban residents should have trees in their communities, to support environmental justice and equity. Converting evidence to economics is complicated, involving the extent of nature around us, the length of time of nature exposure and the traits of beneficiaries. Older people have different health concerns than children with implications for health support. But we learned that trees are an important social determinant of health. The U.S. spends nearly twenty percent of its gross domestic product on healthcare every year, and this amounts to trillions of dollars. The costs to each person is an average of more than $10,00 per year. If an investment in the urban forest can reduce healthcare costs by even a small amount, say five percent, then these avoided costs can be used to support trees and better human quality of life.
Wolf, K.L., S.T. Lam, J.K. McKeen, G.R.A. Richardson, M. van den Bosch, and A.C. Bardekjian. 2020. Urban trees and human health: A scoping review. International Journal of Environmental Research and Public Health
Barron, S., Nitoslawski, S., Wolf, K. L., Woo, A., Desautels, E., & Sheppard, S. R. J. 2019. Greening blocks: A conceptual typology of practical design interventions to integrate health and climate resilience co-benefits. International Journal of Environmental Research and Public Health