Benefits Of Trees

Urban Trees:

• Heating: Using trees as windbreaks allows savings of 10% – 20%* Cooling: Shading windows and walls can lower AC costs by 25% – 50%* Reduction of our energy demands reduces our use of fossil fuels.
• Produce a sense of rootedness and community.
• Help to cool cities by reducing heat sinks. Heat sinks are 6-19 degrees Fahrenheit warmer than their surroundings (Global Releaf-Georgia). A tree can be a natural air conditioner. The evaporation from a single large tree can produce the cooling effect of 10 room size air conditioners operating 20 hours a day. (USDA pamphlet # FS-363)
• Soften harsh contours of buildings.
• Increase commercial and residential property values. Homes on lots with many trees have 6% – 12% higher appraised values. * Trees can help increase the value of your property, sometimes by 10% – 20%. (USDA pamphlet # FS-363)
• Trees act as a carbon-sink by removing the carbon from CO2 and storing it as a cellulose in the trunk while releasing oxygen back into the air. Trees can absorb carbon dioxide at the rate of 26 pounds per year – especially young trees that are still growing. (Global Releaf-Georgia). One tree that shades your home will also save fossil fuel, cutting CO2 buildup as much as 15 forest trees. (The National Arbor Day Foundation pamphlet # 90980005)
• Freshen the atmosphere with the trees own pleasant fragrances. For example, 1 cherry tree can perfume the air with 200,000 flowers. (USDA pamphlet # FS-363)
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Source * Enviro News/Louisiana Gateway 2020. Spring/Summer 1993, Vol. IV

FOREST TREES:

• Trees store carbon and clean the atmosphere. In 50 years, one tree generates $30,000 in oxygen, recycles $35,000 of water, and removes $60,000 of air pollution. **
• Recharge groundwater and sustain streamflow. **
• Supply material for houses, furniture, paper products, etc.
• Crop yields of fields with windbreaks are significantly higher than those without windbreaks. **
• Provide food: nutmeats (walnuts, pecans, hickory, etc.), fruit (plums, peaches, apples, pears), berries for jams and jellies, sap for maple syrup. **
• Living snow fences, strategically placed, hold snow away from roads, reducing maintenance costs. **
• Provide watersheds for city reservoirs
• Absorb dust and heat. Reduce glare.
• Increase atmospheric moisture; reduce environmental water consumption.
• Some trees even provide key medicinal ingredients for illness cures and treatments.
• One out of every four pharmaceutical products used in the US comes from tropical forest plants. **
• Provides necessary habitats for thousands of animals from birds to land animals to water animals.

** Source: USDA Forest Service Pamphlet# R1-92-100

RIPARIAN (RIVERSIDE) TREES:

• Slow floodwaters
• Filter runoff and sediment from slopes next to the stream.
• Increases groundwater supply, which we use as a water supply for cities.
• Provides shade so water animals can survive, keeps the river cool, provides food for water-loving animals. Fish require healthy riparian areas and will sometimes die without them.
• Provides necessary homes for a variety of birds.
• Provides habitats for animals such as beavers and otters.

NOTE: All riparian information taken from USDA pamphlet # FS-445, January, 1990

CARBON SEQUESTRATION:
Heat from Earth is trapped in the atmosphere due to high levels of carbon dioxide (CO2) and other heat-trapping gases that prohibit it from releasing heat into space — creating a phenomenon known as the “greenhouse effect.” Trees remove (sequester) CO2 from the atmosphere during photosynthesis to form carbohydrates that are used in plant structure/function and return oxygen back to the atmosphere as a byproduct. About half of the greenhouse effect is caused by CO2. Trees therefore act as a carbon sink by removing the carbon and storing it as cellulose in their trunk, branches, leaves and roots while releasing oxygen back into the air.
Trees also reduce the greenhouse effect by shading our homes and office buildings. This reduces air conditioning needs up to 30%, thereby reducing the amount of fossil fuels burned to produce electricity. This combination of CO2 removal from the atmosphere, carbon storage in wood, and the cooling effect makes trees a very efficient tool in fighting the greenhouse effect. (11)
One tree that shades your home in the city will also save fossil fuel, cutting CO2 buildup as much as 15 forest trees. (16)
In one urban park (212 ha), tree cover was found to remove daily 48 lbs particulates, 9 lbs nitrogen dioxide, 6 lbs sulfur dioxide, and 1/2 lbs carbon monoxide. ($136 per day value based upon pollution control technology)

Planting trees remains one of the cheapest, most effective means of drawing excess CO2 from the atmosphere. (15)
A single mature tree can absorb carbon dioxide at a rate of 48 lbs./year and release enough oxygen back into the atmosphere to support 2 human beings. (10)
Each person in the U.S. generates approximately 2.3 tons of CO2 each year. A healthy tree stores about 13 pounds of carbon annually — or 2.6 tons per acre each year. An acre of trees absorbs enough CO2 over one year to equal the amount produced by driving a car 26,000 miles. An estimate of carbon emitted per vehicle mile is between 0.88 lb. CO2/mi. – 1.06 lb. CO2/mi. (Nowak, 1993). Thus, a car driven 26,000 miles will emit between 22,880 lbs CO2 and 27,647 lbs. CO2. Thus, one acre of tree cover in Brooklyn can compensate for automobile fuel use equivalent to driving a car between 7,200 and 8,700 miles. (8)
If every American family planted just one tree, the amount of CO2 in the atmosphere would be reduced by one billion lbs annually. This is almost 5% of the amount that human activity pumps into the atmosphere each year. (17)
The U.S. Forest Service estimates that all the forests in the United States combined sequestered a net of approximately 309 million tons of carbon per year from 1952 to 1992, offsetting approximately 25% of U.S. human-caused emissions of carbon during that period.
Over a 50-year lifetime, a tree generates $31,250 worth of oxygen, provides $62,000 worth of air pollution control, recycles $37,500 worth of water, and controls $31,250 worth of soil erosion. (2) Reduction of Other Air Pollutants:
Trees also remove other gaseous pollutants by absorbing them with normal air components through the stomates in the leaf surface. (3)
Some of the other major air pollutants and their primary sources are:
Sulfur Dioxide (SO2)- Coal burning for electricity/home heating is responsible for about 60 percent of the sulfur dioxide in the air. Refining and combustion of petroleum products produce 21% of the SO2.
Ozone (O3) – is a naturally occurring oxidant, existing in the upper atmosphere. O3 may be brought to earth by turbulence during severe storms, and small amounts are formed by lighting. Most O3 – and another oxidant, peroxyacetylnitrate (PAN) – come from the emissions of automobiles and industries, which mix in the air and undergo photochemical reactions in sunlight. High concentrations of O3 and PAN often build up where there are many automobiles.
Nitrogen oxides – Automotive exhaust is probably the largest producer of NOx. Oxides of nitrogen are also formed by combustion at high temperatures in the presence of two natural components of the air; nitrogen and oxygen.
Particulates are small (<10 microns) particles emitted in smoke from burning fuel, particular diesel, that enters our lungs and cause respiratory problems. (10)
There is up to a 60% reduction in street level particulates with trees. (1)
In one urban park (212 ha.) tree cover was found to remove daily 48lbs. particulates, 9 lbs nitrogen dioxide, 6 lbs sulfur dioxide, and 2 lb carbon monoxide ($136/day value based upon pollution control technology) and 100 lbs of carbon. (1)
One sugar maple (12″ DBH) along a roadway removes in one growing season 60mg cadmium, 140 mg chromium, 820 mg nickel, and 5200 mg lead from the environment. (1)
Planting trees and expanding parklands improves the air quality of Los Angeles county. A total of 300 trees can counter balance the amount of pollution one person produces in a lifetime.(10)

The Value of Trees to a Community

The following are some statistics on just how important trees are in a community setting.

“The net cooling effect of a young, healthy tree is equivalent to ten room-size air conditioners operating 20 hours a day.” —U.S. Department of Agriculture

“If you plant a tree today on the west side of your home, in 5 years your energy bills should be 3% less. In 15 years the savings will be nearly 12%.” —Dr. E. Greg McPherson, Center for Urban Forest Research

“A mature tree can often have an appraised value of between $1,000 and $10,000.” —Council of Tree and Landscape Appraisers

“In one study, 83% of realtors believe that mature trees have a ‘strong or moderate impact’ on the salability of homes listed for under $150,000; on homes over $250,000, this perception increases to 98%.” —Arbor National Mortgage & American Forests

“Landscaping, especially with trees, can increase property values as much as 20 percent.” —Management Information Services/ICMA

“One acre of forest absorbs six tons of carbon dioxide and puts out four tons of oxygen. This is enough to meet the annual needs of 18 people.” —U.S. Department of Agriculture

“There are about 60– to 200-million spaces along our city streets where trees could be planted. This translates to the potential to absorb 33 million more tons of CO2 every year, and saving $4 billion in energy costs.” —National Wildlife Federation

“Trees properly placed around buildings can reduce air conditioning needs by 30 percent and can save 20–50 percent in energy used for heating.” —USDA Forest Service

“Trees can be a stimulus to economic development, attracting new business and tourism. Commercial retail areas are more attractive to shoppers, apartments rent more quickly, tenants stay longer, and space in a wooded setting is more valuable to sell or rent.” —The Arbor Day Foundation

“Healthy, mature trees add an average of 10 percent to a property’s value.” —USDA Forest Service

“The planting of trees means improved water quality, resulting in less runoff and erosion. This allows more recharging of the ground water supply. Wooded areas help prevent the transport of sediment and chemicals into streams.” —USDA Forest Service

“In laboratory research, visual exposure to settings with trees has produced significant recovery from stress within five minutes, as indicated by changes in blood pressure and muscle tension.” —Dr. Roger S. Ulrich Texas A&M University

“Nationally, the 60 million street trees have an average value of $525 per tree.” —Management Information Services

To help locate New York City’s heritage trees, the City Department of Parks and Recreation conducted a program called the “Great Tree Search.” New Yorkers looked for trees of unusual size and age, those linked with historic landmarks, and trees of unusual species or location. On Arbor Day, they held a big party to celebrate New York City’s Great Trees.
After a tornado destroyed more than 800 trees in Cardington, Ohio, citizens organized a tree restoration committee which solicited donations and memorials. Volunteers who learned of the tree planting through local newspaper articles appeared on Arbor Day to wrap trunks, water, mulch, and stake 40 large trees which were planted along major streets.

Identified Benefits of Community Trees and Forests
by Dr. Rim D. Coder, University of Georgia
October 1996

Community trees and forests are valuable. To the 75% of the United States population that now live in urban and suburban areas, trees provide many goods and services. Values are realized by the people that own the trees, by people nearby, and by society in general. People plant, maintain, conserve, and covet trees because of the values and benefits generated.

Tree benefits can be listed in many forms. The bottom-line is humans derive not a single-user value from community trees and forests, but a multi-product / multi-value benefit. Some of these benefits stem from components and attributes of a single tree, while other benefits are derived from groups of trees functioning together. What is the value of these multiple benefits? A 1985 study concluded that the annual ecological contribution of an average community tree was $270.

Values, functions, goods and services produced by community trees and forests can be evaluated for economic and quality of life components. While quality of life values are difficult to quantify, some of the economic values can suggest current and future negative or positive cash flows. In assessing changes in dollar values, concerns for tree evaluation are most prevalent within: risk management costs (liability and safety); value-added / capital increases to tree values; appreciation of tree and forest assets; maintenance costs of tree and forest assets; and, level of management effectiveness and efficiency (total quality management of community trees and forests — TTQM).

Below are listed a selected series of goods, services, and benefits community trees across the nation and forests provide. These bullets of information are taken from a diversity of individual research projects and, as such, are individually meaningless except under similar conditions. These items together do suggest trends and concepts of value.

Environmental Benefits
Temperature and Energy Use

Community heat islands (3 to 10 degrees F warmer than surrounding countryside) exist because of decreased wind, increased high density surfaces, and heat generated from human associated activities, all of which requires addition energy expenditures to off-set. Trees can be successfully used to mitigate heat islands. Trees reduce temperatures by shading surfaces, dissipating heat through evaporation, and controlling air movement responsible for advected heat.

Shade

– 20 degrees F lower temperature on a site from trees.
– 35 degrees F lower hard surface temperature under tree shade than in full summer sun.
– 27% decrease in summer cooling costs with trees.
– 75% cooling savings under deciduous trees.
– 50% cooling energy savings with trees. (1980) 20 degrees F lower room temperatures in uninsulated house during summer from tree shade.
– $242 savings per home per year in cooling costs with trees.
– West wall shading is the best cooling cost savings component.
– South side shade trees saved $38 per home per year.
– 10% energy savings when cooling equipment shaded (no air flow reduction).
– 12% increase in heating costs under evergreen canopy
– 15% heating energy savings with trees, (1980)
– 5% higher winter energy use under tree shade
– $122 increase in annual heating costs with south and east wall shading off-set by $155 annual savings in cooling costs.
– Crown form and amount of light passing through a tree can be adjusted by crown reduction and thinning.
– Shade areas generated by trees are equivalent to $2.75 per square foot of value (1975 dollars).

Wind Control

– 50% wind speed reduction by shade trees yielded 7% reduction in heating energy in winter.
– 8% reduction in heating energy in home from deciduous trees although solar gain was reduced.
– $50 per year decrease in heating costs from tree control of wind.
– Trees block winter winds and reduces “chill factor.”
– Trees can reduce cold air infiltration and exchange in a house by maintaining a reduced wind or still area.
– Trees can be planted to funnel or baffle wind away from areas — both vertical and horizontal concentrations of foliage can modify air movement patterns.
– Blockage of cooling breezes by trees increased by $75 per year cooling energy use.

Active Evaporation

– 65% of heat generated in full sunlight on a tree is dissipated by active evaporation from leaf surfaces.
– 17% reduction in building cooling by active evaporation by trees.
– One acre of vegetation transpires as much as 1600 gallons of water on sunny summer days.
– 30% vegetation coverage will provide 66% as much cooling to a site as full vegetation coverage.
– A one-fifth acre house lot with 30% vegetation cover dissipates as much heat as running two central air conditioners.

Air Quality —

Trees help control pollution through acting as biological and physical nets, but they are also poisoned by pollution.

Oxygen Production —

One acre of trees generates enough oxygen each day for 18 people.

Pollution Reduction

– Community forests cleanse the air by intercepting and slowing particulate materials causing them to fall out, and by absorbing pollutant gases on surfaces and through uptake onto inner leaf surfaces.
– Pollutants partially controlled by trees include nitrogen oxides, sulfur dioxides, carbon monoxide,
carbon dioxide (required for normal tree function), ozone, and small particulates less than 10 microns in size.
– Removal of particulates amounts to 9% across deciduous trees and 13% across evergreen trees.
– Pollen and mold spore, are part of a living system and produced in tree areas, but trees also sweep out of the air large amounts of these particulates.
– In one urban park (212 ha), tree cover was found to remove daily 48 lbs particulates, 9 lbs nitrogen dioxide, 6 lbs sulfur dioxide, and 1/2 lbs carbon monoxide. ($136 per day value based upon pollution control technology).
– 60% reduction in street level particulates with trees.
– One sugar maple (one foot in diameter) along a roadway removes in one growing season 60 mg cadmium, 140 mg chromium, 820 mg nickel and 5200mg lead from the environment.
– Interiorscape trees can remove organic pollutants from indoor air.

Carbon Dioxide Reduction

– Approximately 800 million tons of carbon are currently stored in US community forests with 6.5 million tons per year increase in storage ($22 billion equivalent in control costs).
– A single tree stores on average 13 pounds of carbon annually.
– A community forest can store 2.6 tons of carbon per acre per year.

Hydrology

– Development increases hard, non-evaporative surfaces and decreases soil infiltration — increases water volume, velocity and pollution load of run-off — increases water quality losses, erosion, and flooding.
– Community tree and forest cover intercepts, slows, evaporates, and stores water through normal tree functions, soil surface protection, and soil area of biologically active surfaces.

Water Run-Off

– 7% of winter precipitation intercepted and evaporated by deciduous trees.
– 22% of winter precipitation intercepted and evaporated by evergreen trees.
– 18% of growing season precipitation intercepted and evaporated by all trees.
– For every 5% of tree cover area added to a community, run-off is reduced by approximately 2%
– 7% volume reduction in six-hour storm flow by community tree canopies.
– 17% (11.3 million gallons) run-off reduction from a twelve-hour storm with tree canopies in a medium sized city ($226,000 avoided run-off water control costs).

Water Quality / Erosion

– Community trees and forests act as filters removing nutrients and sediments while increasing ground water recharge.
– 37,500 tons of sediment per square mile per year comes off of developing and developed landscapes — trees could reduce this value by 95% ($336,000 annual control cost savings with trees).
– 47% of surface pollutants are removed in first 15 minutes of storm — this includes pesticides, fertilizers, and biologically derived materials and litter.
– 10,886 tons of soil saved annually with tree cover in a medium-sized city.

Noise Abatement

– 7db noise reduction per 100 feet of forest due to trees by reflecting and absorbing sound energy (solid walls decrease sound by 15 db)
– Trees provide “white noise, ” the noise of the leaves and branches in the wind and associated natural sounds, that masks other man-caused sounds.

Glare Reduction

– Trees help control light scattering, light intensity, and modifies predominant wavelengths on a site.
– Trees block and reflect sunlight and artificial lights to minimize eye strain and frame lighted areas where needed for architectural emphasis, safety, and visibility.

Animal Habitats

– Wildlife values are derived from aesthetic, recreation, and educational uses.
– Lowest bird diversity is in areas of mowed lawn — highest in area of large trees, greatest tree diversity, and brushy areas.
– Highest native bird populations in areas of highest native plant populations.
– Highly variable species attributes and needs must be identified to clearly determine tree and community tree and forest influences.
– Trees are living systems that interact with other living things in sharing and recycling resources – as such, trees are living centers where living thing congregate and are concentrated.

Economic Stability Community

– Community trees and forests provide a business generating, and a positive real estate transaction appearance and atmosphere.
– Increased property values, increased tax revenues, increased income levels, faster real estate sales turnover rates, shorter unoccupied periods, increased recruitment of buyers, increased jobs, increased worker productivity, and increased number of customers have all been linked to tree and landscape presence.
– Tree amenity values are a part of real estate prices.

Property Values — Real Estate Comparisons

– Clearing unimproved lots is costlier than properly preserving trees.
– 6% ($2,686) total property value in tree cover.
– $9,500 higher sale values due to tree cover.
– 4% higher sale value with five trees in the front yard — $257 per pine, $333 per hardwood, $336 per large tree, and $0 per small tree.
– $2,675 increase in sale price when adjacent to tree green space as compared to similar houses 200 feet away from green space.
– $4.20 decrease in residential sales price for every foot away from green space.
– 27% increase in development land values with trees present.
– 19% increase in property values with trees. (1971 & 1983)
– 27% increase in appraised land values with trees. (1973)
– 9% increase in property value for a single tree. (198 1)

Property Values – Tree Value Formula (CTLA 8th edition)

– Values of single trees in perfect conditions and locations in the Southeast range up to $100,000.
– $100 million is the value of community trees and forests in Savannah, GA
– $386 million is the value of community trees and forests in Oakland, CA (59% of this value is in residential trees).

Product Production

– Community trees and forests generate many traditional products for the cash and barter marketplace that include lumber, pulpwood, hobbyist woods, fruits, nuts, mulch, composting materials, firewood, and nursery plants.

Aesthetic Preferences

– Conifers, large trees, low tree densities, closed tree canopies, distant views, and native species all had positive values in scenic quality.
– Large old street trees were found to be the most important indicator of attractiveness in a community.
– Increasing tree density (optimal 53 trees per acre) and decreasing understory density are associated with positive perceptions.
– Increasing levels of tree density can initiate feelings of fear and endangerment — an optimum number of trees allows for visual distances and openness while blocking or screening developed areas.
– Species diversity as a distinct quantity was not important to scenic quality.

Visual Screening

– The most common use of trees for utilitarian purposes is screening undesirable and disturbing sight lines.
– Tree crown management and tree species selection can help completely or partially block vision lines that show human density problems, development activities, or commercial / residential interfaces.

Recreation

– Contact with nature in many communities may be limited to local trees and green areas (for noticing natural cycles, seasons, sounds, animals, plants, etc.) Trees are critical in this context.
– $1.60 is the willing additional payment per visit for use of a tree covered park compared with a maintained lawn area.

Health

– Stressed individuals looking at slides of nature had reduced negative emotions and greater positive feelings than when looking at urban scenes without trees and other plants.
– Stressed individuals recuperate faster when viewing tree filled images.
– Hospital patients with natural views from their rooms had significantly shorter stays, less pain medicine required, and fewer post-operative complications.
– Psychiatric patients are more sociable and less stressed when green things are visible and immediately present.
– Prison inmates sought less health care if they had a view of a green landscape.

Human Social Interactions

– People feel more comfortable and at ease when in shaded, open areas of trees as compared to areas of hardscapes and non-living things.
– People’s preferences for locating areas of social interactions in calming, beautiful, and nature-dominated areas revolve around the presence of community trees and forests.
– Trees and people are psychologically linked by culture, socialition, and co adaptive history.

Reference for most of this material: Literature Review for the QUANTITREE computer program —
“Quantifiable Urban Forest Benefits and Costs; Current Findings and Future Research.” In a white paper entitled Consolidating and Communicating Urban Forest Benefits. Davey Resource Group, Kent, OH.
1993. Pp.25.
THE UNIVERSITY OF GEORGIA, THE UNITED STATES DEPARTMENT OF AGRICULTURE AND COUNTIES OF THE STATE COOPERATING. THE COOPERATIVE EXTENSION SERVICE OFFERS EDUCATIONAL PROGRAMS, ASSISTANCE AND MATERIALS TO ALL PEOPLE WITHOUT REGARD TO RACE, COLOR, NATIONAL ORIGIN AGE, SEX OR HANDICAP STATUS.
A UNIT OF THE UNIVERSITY SYSTEM OF GEORGIA. AN EQUAL OPPORTUNITY/ AFFIRMATIVE ACTION ORGANIZATION THE UNIVERSITY OF GEORGIA COOPERATIVE EXTENSION SERVICE FOREST RESOURCES
UNIT PUBLICATION FOR96-39

Trees as an investment

Trees provide numerous aesthetic and economic benefits, but also incur some costs. Investing in a tree’s maintenance will help to return the benefits you desire. The costs associated with large tree removal and replacement can be significant. In addition, the economic and environmental benefits produced by a young replacement tree are minimal when compared to those of a mature specimen. Extending the functional lifespan of large, mature trees with routine maintenance can delay these expenses and maximize returns.
An informed home owner can be responsible for many tree maintenance practices. Corrective pruning and mulching gives young trees a good start. Shade trees, how¬ever, quickly grow to a size that may require the services of a professional arborist. Arborists have the knowledge and equipment needed to prune, treat, fertilize, and otherwise maintain a large tree. Your garden center owner, university extension agent, community forester, or consulting arborist can answer questions about tree maintenance, suggest treatments, or recommend qualified arborists.

What a Large Tree Can Do For You

A large front yard tree in a San Joaquin Valley community like Modesto (dry like Colorado) provides the following benefits each year:
1. Saves $30 in summertime air conditioning by shading the building and cooling the air (250 kWh), about 9% of total annual air conditioning cost.
2. 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.
3. 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.
4. 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.
5. 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. Our benefit-cost analysis for Modesto’s 90,000 street/park trees found $1.89 returned annually for every $1 invested in stewardship.
–Greg McPherson