Trees and Urban Forests

October 1, 2013, Department, by Richard J. Dolesh

 Trees and urban forests provide more than just economic and environmental benefits.A solid body of knowledge exists about the economic and environmental value of trees and urban forests to local communities. City after city has seen the wisdom — and the quantifiable benefits — of investing in their urban forests. And recently, some high-quality, user-friendly online tools have become available to assess the economic and environmental benefits of community trees, notably the excellent software program iTree, which was developed by the U.S. Forest Service, Davey Tree Company and other cooperators.  

However, there has been less research and consequently less data on other long-term benefits of trees and urban forests, particularly the health benefits of trees to urban communities, and there is even less research on the social equity components and environmental justice benefits of trees and urban forests.  

Fortunately, there is some good research emerging, even if it is negatively pointing to racial and economic disparities due to a lack of trees in minority and underserved communities. Recent research reported in the journal Environmental Health Perspectives (EHP) detailed the results of a study by Bill M. Jesdale, Rachel Morello-Frosch and Lara Cushing regarding the racial/ethnic composition and distribution of residential communities according to “heat-risk-related land cover” (HRRLC). The study compared degrees of racial segregation across types of racial/ethnic groups with regard to heat-risk-related land cover, or in other words, the risks to certain urban populations from the presence or absence of tree canopy cover relative to the amount of impervious surfaces from parking lots, building roofs and other hardscape urban development.

When all variables were taken into consideration, the researchers found that every type of ethnic and racial minority group had a higher — and in some cases, much higher — incidence of heat-related risk due to land cover variation. Non-Hispanic blacks were 52 percent more likely to live in such heat-related conditions, non-Hispanic Asians were 32 percent more likely, and Hispanics were 21 percent more likely to live in heat-risk-related land cover conditions than non-Hispanic whites. In fact, these negative conditions grew worse with increasing levels of metropolitan segregation. The research team stated: “To our knowledge, no study has examined this issue nationally or assessed the role that residential segregation plays in driving distributions of urban tree coverage among racial/ethnic groups in the United States.”

Predominately minority communities affected by such disparities will find no good news in these findings. For one, it means that the health and well-being of everyone in these communities, young and old alike, is likely to be negatively affected by greater urban heat-island effects, higher ambient daytime and nighttime temperatures, greater impacts from UV radiation, more noise, more air pollution, less shade and comfort in public places, and possibly a range of other as yet known or quantified impacts. Secondly, such conditions will likely tend to get worse rather than better if no changes are made in the urban landscape as climate change and extreme heat events begin to affect urban cities with greater intensity.

So, what do these findings mean for public parks and recreation? We might be feeling a little smug. After all, we are the stewards of public parks, the places where trees grow. It goes without saying that we value and promote trees for their health benefits — right? Well, as it turns out, maybe not so much.  

A recent survey on shade policies conducted by GP RED, a Colorado-based nonprofit, had some interesting implications for parks and recreation, especially when it comes to the matter of trees in the urban landscape. The survey of professionals from parks, recreation and public health fields found that only a fifth of the agencies and organizations responding had formal polices regarding providing shade in outdoor recreation areas and facilities, and less than a third of responding agencies addressed providing shade in their local planning process. The survey did not distinguish between shade from manmade shade structures and shade produced by trees, but the percentage of shade cover in urban park settings that comes from trees and vegetation is significantly higher than from shade structures. The fact that so few public agencies consider provision of shade in the planning process (70 percent do not) and that 13 percent of respondents didn’t even know if they addressed shade in the planning process indicates at a minimum that there is a disconnect in how many park and recreation agencies regard the importance of trees and urban forests in parks.  

Clearly, there are lessons for parks and recreation to take away from the research study in EHP and the GP RED survey regarding the importance of the health benefits of trees and urban forests. Among the most important takeaways, perhaps, is that as the largest owners of urban open space, park and recreation agencies should give greater priority to providing more tree canopy cover in urban parks and planting more trees in public spaces. Yes, it is true that many mayors and elected officials in big cities across the nation have adopted truly ambitious tree-planting goals, and many park and recreation agencies are integrally involved in implementing such goals, but a more comprehensive approach to the health benefits of trees and urban forests should be made a planning priority.

The study reported in Environmental Health Perspectives graphically points out the disparities of heat-related risk according to land cover in segregated residential minority communities and makes recommendations that the increasing incidence of extreme heat events and climate change adaptation strategies should be taken into consideration by planting trees in a way that incorporates an environmental justice framework. However, it is not clear to whom their recommendations should apply — elected officials, community planners, landscape architects? Yes, these recommendations should be directed to them and to many others, but we in parks and recreation should also recognize that we have a responsibility and an unique opportunity for action, for we are the stewards of the most vitally important open space lands in urban communities.  

Park and recreation agencies truly have the potential to make a measurable difference in every community, but there is especially an opportunity to improve social equity and provide greater contributions to environmental justice in underserved communities by addressing how we manage the land and provide the benefits of trees and urban forests.

Click here for the full EHP study on the impacts of heat-risk-related land cover. Click here for a link to the GP RED survey on shade policies.

Richard J. Dolesh is NRPA's Vice President of Conservation and Parks.