The Benefits of a Healthy Urban Tree Canopy for Baltimore City
By: Matt Heilman
April 24, 2013

The city of Baltimore would face both costs and benefits in achieving a healthy tree canopy. However, the benefits would far outweigh the costs that are associated in achieving this goal. The city of Baltimore would benefit greatly from a more significant investment in improving the tree canopy. Trees are one of the few elements of our infrastructure that increase in value over time. Trees remove air pollutants, alter microclimates, and reduce air temperature. Tree also absorb and filter water, cool our homes and business and increase property value. They are known to reduce stress, aggression and asthma rates and increase the livability and vitality of our neighborhoods and businesses.
A tree canopy is the percent of a city’s land area that has tree cover (MDNR. 2008). Many cities in the U.S., including Baltimore have seen a major reduction in tree and forest cover over the past several decades (U.S. Forest Services). In 2003 the Chesapeake Bay Executive Council Directive 03-01 recognized that “urban tree canopy cover offers water quality benefits for municipalities” (TreeBaltimore). American Forests, a pioneer in the science of urban forestry, determined that the healthiest cities have a 40% tree canopy (TreeBaltimore). This encouraged communities to adopt urban tree canopy goals. Working with the Maryland Department of Natural Resources and the U.S. Forest Services, Baltimore City was the first jurisdiction in the area to adopt a goal to significantly improve their tree canopy. Baltimore City’s goal is to increase the tree canopy to 40% by 2037(City of Baltimore). This is a very aggressive goal that requires participation from all sectors in the city. Charles Murphy, TreeBaltimore’s operation manager states “Forty percent is a very high number. When we started, we were only at 27 percent. With a city the size of Baltimore, you’re talking about planting more than a million trees in 30 years with little budget set up to do it. So it’s very ambitious to say the least.” TreeBaltimore, the city’s Urban Forest management plan, initiated in 2009 by Mayor Sheila Dixon is aimed at “preserving the urban tree canopy to create a greener more healthy city.” (TreeBaltimore). The TreeBaltimore program was designed to cooperate with government agencies, local institutions, non-profits, businesses, schools and most importantly the residents of Baltimore. An analysis of the urban tree canopy, using high resolution aerial imagery, determined Baltimore has a 27.4% tree canopy covering 14,130 of the 52,333 acres of Baltimore (TreeBaltimore). They also estimate the Baltimore metropolitan area has about 2.8 million trees. But one-fourth are distressed, dead of dying (U.S. Forest Service). The Forest Service’s urban tree canopy assessment revealed that a large amount of available planting space is on private property. To reach its 40 percent tree canopy goal, the city must plant approximately 750,000 trees — about 25,000 to 30,000 each year. Currently, about 7,500 are planted per year (Baltimore Tree Trust).
Cost
To put a value on the costs I will look at the how much money the city is designated towards improving the urban tree canopy, most notably TreeBaltimore. In addition to state funding, TreeBaltimore receives a $1.2 million annual grant from Constellation Energy (TreeBaltimore).

Assessing the current urban forest consists of several elements in itself. The use of updated satellite and aerial imagery comes at no cost provided by U.S. Forest Service. Inventory of street, park and school tress to assess quantity and species diversity and including a master plan for large parks comes at a cost of $77,000 per year (TreeBaltimore). Partnering with communities to conduct front and back yard tree inventory is still an unknown cost. However according to Erik Dihle, city arborist, “community participation is key in keeping TreeBaltimore’s labor costs down” due to free labor of volunteers. Tracking and assessing survival rates of young trees for the first 3 years, which is their most critical life stage, would be carried out by forestry inspectors while carrying out routine operations. This cost would be incorporated into the forestry division at no additional costs to forestry. The most expensive cost of assessing the current urban forest would come with computer related costs. It would require a hardware and software package consisting of specialized tablets and a computer support personal; this would come at a cost of around $80,000 (TreeBaltimore).
Creating awareness and understanding of the benefits of urban forests consist of several actions. Such action include: establishing a marketing team, designing a web page and participating in community events. Because a majority of available land is located on private property, community support is pivotal in achieving the goal. TreeBaltimore designates around $50,000 a year towards marketing and community outreach. The operational budget of TreeBaltimore is the most costly, coming in at around $500,000. Their operations consist of mapping optimal planting spaces, contacting partner groups to coordinate tree plantings, providing incentives for homeowners through free tree giveaways and workshops, and buying trees and tools. Protecting the current state of the urban forest is a key element in achieving their goal. This comes at a cost to the city at $48,000 per year, which would employ staff to monitor trees (TreeBaltimore).
TreeBaltimore is a partnership with the Forestry Division of Baltimore. It currently has one full time employee. TreeBaltimore’s total budget from grants and funding totals less than $1.7 million per year.
Benefits
The benefits of a healthy urban forest extend beyond simple economics. Baltimore’s parks provide people with a place to relax and escape the hectic streets. Green spaces improve on physical and mental health, strengthen our communities and make our cities a more attractive place to work and live (Florida, 2000). They also improve behavior of children in school environments (Wolf). Research has shown that that people who have a view of nature from their office are happier at work. Trees also provide a buffer between pedestrians and cars and have shown to slow down the speed of cars (Kuo, 2001). Healthy trees attract shoppers to local businesses (Kuo, 2001). Several other studies have shown people are willing to drive further distances, visit more frequently, and pay more for good and services in areas with trees (Casey Trees, 2008). Studies have shown that homes with higher tree cover sell for more. A 10% increase in tree cover increases average home sale by $1371 (Sander, 2010).
Trees roots are natures best pollution filtration system. They also prevent soil erosion (EPA). A leading cause of water pollution is untreated rainwater or stormwater runoff from city streets. Trees help to reduce the flow of stormwater runoff, which can contain pollutants such as oils, fertilizers, salt and other pollutants. The result of polluted and excess runoff leads to fish kills, destruction on wildlife habitat and contaminates drinking water (EPA).
The leaves of trees reduce pollution by trapping fine particles and returning oxygen to the atmosphere (Nowak,2000). Baltimore’s Urban Forest can remove 772 tons of air pollution annually. Each tree removes about 4.41 pounds of total pollution. If the city had to pay to have that amount of pollution removed, it would cost about $3.8 million per year (Nowak, 2000). Trees reduce the greenhouse effect by absorbing carbon dioxide, the major element of greenhouse gas problems (EPA, 2008). On average a mature tree can absorb 48 pounds of carbon dioxide each year (McAliney,1993). It is estimated that Baltimore has about 2,835,500. That many trees can store approximately 581,249 tons of carbon (Nowak, 2000).
Ground level ozone is caused when strong sunlight reacts with pollutants such as fumes from vehicles or emissions from power plants (MDE, 2008). The main ozone-causing pollutants are volatile organic compounds (VOC) and nitrogen oxides (MDE, 2008). Ground level ozone in the main ingredient for smog (EPA).High level ozone can affect anyone but particularly the young and elderly (EPA). Ozone can significantly affect the respiratory system by reducing lung function. Annually Baltimore’s trees remove about 269 tons of ozone. Removing the amount of ozone without trees would cost about $1.6 million per year. With this amount removed the air quality is improved by 51% (Nowak, 2000).
Trees also help cool the city by releasing water vapor, which increases cloud cover and limits direct sun rays (McPherson, 2007). When trees are planted near buildings the provide shade in summer and wind breaks in winter, therefore less heat is required in the winter and less air conditioning in the summer. This reduces energy costs and usage. In monetary value, trees can provide $242 savings per home per year in cooling costs and $50 per year in heating costs (Coder, 1996). Trees can shade and cool surfaces, reducing the temperature of a surface, which lowers the overall temperature of the air. The weather-related benefits on trees can save the citizens of Baltimore up to $3.3 million a year in energy costs (Coder, 1996).
Figure 1 Relationship between park proximity and home value (Luttik)
Figure 1 Relationship between park proximity and home value (Luttik)
A healthy tree canopy would also benefit the wildlife in the area. Trees provide the two most basic necessities wildlife need for survival: shelter and food. If not for trees there would be virtually nowhere for animals to live.
Home value also sees an increase in value the close a property is located to a park. Attractive landscape types were shown to attract a premium of 5–12% over less attractive environmental settings (Luttik, 2000). Luttik incorporated crime statistics into his research and found that areas with lower crime statistics with high tree canopy cover.
The benefits on a healthy urban canopy are numerous. Baltimore City faces many environmental problems, such as air quality and water quality, which can be improved by having a healthy urban forest. Baltimore also faces the challenge of making the city a more desirable place to live and work. Trees enhance the quality of life for city residents and provide space for recreational activities (TreeBaltimore). There are also great economic benefits that can be gained from a health canopy. Trees save money by reducing pollution in the air, water and soil, while also reducing the heat island effect and reducing energy bills.
Discussion
The city of Baltimore has demonstrated that achieving a healthy tree canopy is very important. However the funding and resources allocated to the project do not reflect the benefits that would come with achieving a healthy urban tree canopy. The fact that it is difficult to put a monetary value on many of the benefits from trees makes it challenging in allocating more money. Baltimore is making significant progress towards the adopted goal of achieving a 40% urban tree canopy, but Figure [ 2 ] The U.S. Environmental Protection Agency’s “Eco-Health Relationship Health Science Browser”:
Figure [ 2 ] The U.S. Environmental Protection Agency’s “Eco-Health Relationship Health Science Browser”: efforts are still falling short of the targeted goal. I believe that the city would be more effective in reaching its goal by incentivizing private land owners to plant trees on their property. There are no current policies in place to motivate private landowners to plant on their own. Increased education and awareness has led to new advances in the field of urban forestry. The use of high resolution aerial imagery has played a major role in reducing the costs of assessing the issue. According to TreeBaltimore operational director Charlie Murphy, “additional funding would certainly help us reach our goal. But the most important aspect is community participation.”
Based on the benefits provided, a healthy UTC would outweigh and outlast the costs associated with it. It would address several issues the city is currently addressing, without direct efforts towards those issues.

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