A large front yard tree in a San Joaquin Valley community like Stockton (hot and dry) provides the following benefits each year:
Saves $30 in summertime air conditioning by shading the building and cooling the air (250 kWh), about 9% of total annual air conditioning cost.
Absorbs 10 lbs of air pollutants, including 4 lbs of ozone and 3 lbs of particulates. The value of pollutant uptake by the tree is $45 using the local market price of emission reduction credits. Uptake of NOx by the tree is equivalent to NOx emitted by a typical car driven 3,600 miles.
Intercepts 760 gal of rainfall in its crown, thereby reducing runoff of polluted stormwater and flooding. This benefit is valued at $6 based on local expenditures for water quality management and flood control.
Cleans 330 lbs of CO2 (90 lbs C) from the atmosphere through direct sequestration in the tree's wood and reduced power plant emissions due to cooling energy savings. The value of this benefit is $5 assuming the California Energy Commission's price of $30/ton. This tree reduces the same amount of atmospheric CO2 as released by a typical car driven 500 miles.
Adds about 1% to the sales price of the property, or about $25 each year when annualized over a 40-year period. This assumes a median residential property sales price of $100,000. The value of all benefits is $111 in this example. Typically, a city will spend $20-$40 per year to maintain a street tree of this size (sometimes located in a front yard easement) and a resident will spend about $10 per year maintaining a large yard tree.
A benefit-cost analysis for Modesto's 90,000 street/park trees found $1.89 returned annually for every $1 invested in stewardship..
Street trees unify urban spaces and soften the diverse architectural styles and colors found in neighborhoods and business districts. A well-planned urban tree canopy conveys pride of ownership and care, and signals to the citizens that this is a good place to live.
A well-planned and maintained urban tree canopy greatly affects the aesthetics of the City. Neighborhoods that have tree-lined streets, with branches arching over the travelled way, convey a sense of community.
Properties that have street trees and attractive landscaping are more pleasing to look at as compared to those that do not. Ask any real estate agent which property will get more attention, one that has mature trees or one that is barren?
Studies have estimated that mature street trees may account for up to 15 percent of the value of a residential property. For example, a $200,000 house on a lot with three mature trees might owe as much as $30,000 of its value to the trees.
A University of Washington study found that trees could help improve business. Well-shaded retail centers attract customers that are willing to travel further, shop longer, visit more frequently, and pay up to 11% more for goods and services.
Nearly everyone is aware of the impacts that air pollution and global warming is having on our environment. The urban tree canopy contributes to the improvement of the overall air quality of the community. Tree leaves absorb dirty air and remove pollutants. Particulates of pollution like dust are deposited on the leaves. Trees absorb carbon dioxide and produce oxygen for us to breathe.
The APPA (American Public Power Association) has prepared a Tree Benefit Estimation calculation program. Using SMUD’s Tree Benefit calculation program it is estimated that the urban forest will remove pollutants from the atmosphere as follows:
100 trees remove five (5) tons of
CO2 per year
100 trees remove about 1000 lbs of
pollutants per year, including:
400 lbs of ozone
300 lbs of particulates
Trees provide significant air quality benefits to Stockton by reducing the amount of nitrogen oxide, a component of smog.
n addition to the air quality benefits, trees help reduce summer electrical demands by providing shading of structures and Trees cool the air by releasing moisture into the air through a process called transpiration.
In summer months, urban trees shade buildings and reduce the need for air conditioning. In addition to direct shade on buildings, trees cool entire neighborhoods by releasing moisture (transpiration) into the air and shading highly absorptive surfaces like parking lots and streets that hold heat in the sun. This is a significant factor for Stockton’s climate. In the winter, trees can help reduce heating costs by slowing the wind.
A cohesive urban tree canopy can save property owners up to 30% of annual cooling costs and 10-25% of energy used for heating. The strategic planting of an addition, 100,000 trees in Stockton could result in a $1 million energy savings to the residents.
Areas of the community devoid of urban tree canopy are referred to as the “Urban Heat Island Effect” and will be approximately 7°F hotter than neighborhoods that have street trees and an urban canopy. This additional heat transfers to higher energy use and a corresponding increase in global warming.
Trees provide many general health benefits and help reduce ultraviolet radiation exposure. In the State Department of Health Service’s “State Of The Urban Forest Report”, it is indicated that trees reduce the occurrence of skin cancer. Further, it indicates planting trees where people congregate will reduces skin cancer and reduce health costs. Trees absorb up to 90% of the ultraviolet radiation, provide a natural form of sunscreen equivalent to a SPF of 10-20.
Noise can cause anxiety, tension, or even illness.
Prolonged exposure to high levels of noise can cause hearing loss. Today we
regard noise as a form of environmental pollution, and in some circles, noise is
considered an international health concern.
The urban tree canopy can help reduce the ambient noise of the community. With
an absorptive surface and variable angles their leaves present themselves to a
noise source, up to a five to ten decibels of reduction can be achieved. This
level of attenuation reduces noise approximately 50% to the human ear. Obviously
to achieve this effect, the species and the planting design must be chosen
carefully. A palm tree will not reduce as much noise as a conifer.
A healthy urban tree canopy will support a complex habitat for songbirds as well as birds of prey by providing nesting sites.
Songbirds eat a wide variety of foods, including insects, seeds, berries, nectar, and fruit. Their appetite for insects is unparalleled by few species, and aids the community by keeping insects in check.
With many open waterways traversing through the Stockton, a healthy population of rats, squirrels, possums, and other rodents are born each year. Birds of prey generally pursue and often capture prey on the wing. Many species cover great distances while soaring in search of prey. Species such as the Swenson’s Hawk and Owls specialize in capturing rodents, reptiles, and insects.
A recent scientific study by the University of Illinois at Urbana-Champaign found that the more trees and grass in the common spaces of inner-city neighborhoods, the more those spaces are used by residents. In addition, use of these spaces means more opportunities for informal social interaction. In other words, relationships between neighbors are made stronger simply through the presence of vegetation.
The study also found that, compared to residents living near barren spaces, those closer to green spaces enjoy activities that are more social, have more visitors, know more of their neighbors, and have stronger feelings of belonging. Essentially, greener common areas facilitate the development and maintenance of stronger social ties, the very fabric of a healthy neighborhood.
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