Urban forestry
Urban forestry is the care and management of single trees and tree populations in urban settings for the purpose of improving the urban environment. Also called urban tree canopy, urban forestry involves both planning and management, including the programming of care and maintenance operations of the urban forest.
Urban forestry advocates the role of trees as a critical part of the urban infrastructure. Urban foresters plant and maintain trees, support appropriate tree and forest preservation, conduct research and promote the many benefits trees provide. Urban forestry is practiced by municipal and commercial arborists, municipal and utility foresters, environmental policymakers, city planners, consultants, educators, researchers and community activists. Urban forests mitigate the effects of urban heat island through evapotranspiration and the shading of streets and buildings.
There are many environmental impacts that are associated with the inequity of the urban tree canopy. Strategically, planting trees is a proven method of climate change adaptation and mitigation. Wildlife is also attracted to urban forests for their increased surface waters due to reduced runoff in these areas. Forests that have been included in urban environments have shown beneficial effects for the residents who live there. Urban forestry has been shown to promote psychological healing, stress recovery, and to improve concentration and productivity. Street trees, if managed and cared for, are beneficial in creating sustainable and healthy communities. The inequitable distribution of canopy cover in lower socioeconomic neighborhoods has resulted in many social impacts that raise environmental justice concerns.
Benefits
Environmental and health impacts
Heat waves cause 1,300 deaths each year in the United States alone, which is more than any other weather-related event. As temperatures continue to rise due to global warming, we can expect to see this number increasing in coming years. The risk is exacerbated for low-income households who do not have access to air conditioning, as well as heat-sensitive populations such as the elderly, infants, and those who have chronic health problems.Reforesting a 10-meter radius corresponds to 0.7 degree Celsius decrease in daytime air temperature, compared to a 1.3 degree decrease in a 30-meter radius, and over 1.5 degrees in a 60 or 90 meter radius. This reduces the risk of heat stroke, decreases cooling costs, and improves general well-being.
Trees have saved 1,200 lives annually in the U.S, by preventing heat related deaths. Urban forests improve air quality by absorbing pollutants such as ozone, nitrogen dioxide, ammonia, and particulate matter as well as performing carbon sequestration. Communities with better air quality measures demonstrate lower levels of childhood asthma. Urban forestry can be an important tool for stormwater management as trees intercept rainwater in the canopy, and can slow down, filter and pump water back into the atmosphere via their roots. Other benefits include noise control, traffic control, and glare and reflection control.
Mental health impacts
A 2018 study asked low income residents of Philadelphia "how often they felt nervous, hopeless, restless, depressed and worthless." As an experimental mental health intervention, trash was removed from vacant lots. Some of the vacant lots were "greened", with plantings of trees, grass, and small fences. Residents near the "greened" lots who had incomes below the poverty line reported a decrease in feelings of depression of 68%, while residents with incomes above the poverty line reported a decrease of 41%. Removing trash from vacant lots without installing landscaping did not have an observable mental health impact.Urban forests and green spaces have been associated with milder ADHD symptoms. Children with ADHD struggle with directed attention - a type of attention that is a part of the theory of attention restoration. Directed attention entails "periods of deliberate focus" and requires breaks to continue productivity.
A case study conducted in Belgrade, Serbia evaluated the mental health benefits of The Faculty Urban Forest for a younger population. Time spent in an arboretum is shown to benefit mental health by lowering depression, anxiety, and stress. An ideal forest environment for psychological improvement should have an extensive assortment of coniferous and broadleaved species displaying vibrant colors. These conditions provide a multitude of sensory experiences, which can be experienced with infrastructure such as benches, picnic tables, and pavilions. It is important to provide handicap-accessible options and locate urban forests close to public transportation so that they can support daily visits and restorative experiences for all.
Tree canopy inequity
Urban tree canopy inequity is defined by American Forests as the uneven distribution of urban trees in neighborhoods that are socioeconomically disadvantaged. These neighborhoods that lack sufficient canopy cover compared to areas that have access to suitable canopy cover, experience inaccessibility to the benefits that trees provide, and other social inequalities. Many of the neighborhoods that are most impacted by this inequity are where minorities and impoverished populations reside. This inequity of the urban tree canopy is caused by many social factors, such as environmental racism, which is environmental injustice that largely impacts racial groups by policies or practices, such as redlining policies. This resulted in the trend that poorer and predominantly minority neighborhoods experience less canopy cover.Urban tree canopy inequity limits the access to the beneficial ecosystem services that trees provide. Populations that do not live in neighborhoods with suitable canopy cover do not experience the protection from the impacts of climate change and the urban heat island effect, air and water pollution, trapping of rainfall surface runoff, and energy savings on air conditioning from tree shade. These populations also do not benefit from the psychological benefits that trees provide, such as having areas that increase social cohesion and congregation, recreation, and nature aesthetics.
An example of other social benefits associated with urban tree canopy includes a research study reviewed by The Children & Nature Network, an organization active in the movement of connecting children and their families to nature. Researchers conclude that there is a positive relationship between academic performance and tree cover and species composition, indicating that tree cover and species composition have a positive effect on the academic performance of primary school-aged children, especially those enrolled in socio-economically challenged schools.
A lack of trees in neighborhoods and a heavy presence of impervious surfaces such as houses, sidewalks, and parking lots, contribute to the heat island effect and there is a lack of temperature moderation. In these areas, temperatures are more extreme. Without the presence of trees, there would be poor air quality and an increase in air pollution as trees remove carbon and pollutants from the air through sequestration, and storing it in their structures. A lack of trees would also result in the risk of chemicals and other harmful pollutants entering water sources and collecting on sidewalks and roads, as they would not be present to increase infiltration and to help reduce and manage rainwater runoff. Biodiversity and habitat for animals decline in these areas as trees are not available for animals and plants to utilize.
As urban tree canopy inequity remains present in lower-socioeconomically disadvantaged neighborhoods, impacting the livelihoods and environmental state of these areas and populations, efforts are being made by urban foresters, city officials, and organizations to address this problem and present solutions. Examples of these efforts include the United States Forest Service outreach and education programs. Organizations such as Casey Tree's Community Tree Planting projects, the Greening of Detroit program, and American Forests help to implement programs and initiatives within cities and neighborhoods to engage volunteers, preserve and care for the urban forest and promote educational and career opportunities for the public.
Case studies, such as one based in Washington D.C., analyze and contribute to the knowledge of urban tree canopy inequity by utilizing various methods including interviews, collaboration with private and public organizations, and community outreach that are successful and help present solutions for urban tree canopy inequity. The use of online applications such as i-Tree and its associated tree and forest assessment tools, and Tree Equity Score, along with many others, assist urban foresters, professionals, and students in conducting research on urban areas and presenting planning solutions to urban tree canopy inequity.
Inequities in environmental and health impacts
In the 1930s as part of the New Deal, the federal government started implementing unfair redlining policies, which classified certain neighborhoods as "risky" areas for banks and mortgage lenders to approve in funding home investments. Demographics of these communities typically included higher percentages of Black, African American, and Latino community members. These redlining policies led to overall lack in investment in these areas, including lack of equitable investment in environmental resources. There remain lower percentages of tree canopy coverage in nearly every U.S. city that had formerly redlined neighborhoods, including the three most populous U.S. cities, New York, Chicago, and Los Angeles. People living in urban communities with significantly lower percentages of urban trees do not benefit from the same environmental and health impacts as those in communities with greater tree populations.In New York, specifically, the South Bronx has far fewer trees than New York City neighborhoods with higher income levels. Tree canopy coverage in the Bronx, in general, is the lowest of all five New York City boroughs. There is only 19.86% canopy coverage provided by street trees, which is much lower than the citywide average of 23.98%. The New York City Department of Health's measures how the risk of heat related illness and death differs across city neighborhoods, and it shows that New York City neighborhoods that are more heat-vulnerable, such as those in the South Bronx, tend to have lower tree canopy coverage.
Populations living in these communities are at greater risk for heat related illness, such as heat stroke, or death due to heat waves. Health outcomes associated with air pollution, such as asthma, are also worse off in neighborhoods with lower tree canopy coverage. In the Bronx, childhood asthma rates are disproportionately high. Children in the Bronx visit the emergency room for asthma 2x the rate of children in other boroughs. There are approximately 17% of children suffering from asthma in the Bronx, compared to the citywide average of 11%.