Ontario Tree Spading
Midland, Ontario L4R 1L8
905-510-7159 | phone
Hours of Operation
Open 24 hours 7 days a week!
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The basis for the value of an
urban tree could be emotional, aesthetic, or it could be strictly utilitarian.
However, people seldom perceive value as strictly aesthetic or monetary. There
is often substantial overlap that makes "value" difficulty to
classify. In many communities, public spending on tree care and management
reflects an approximate value of trees. Spending patterns that go unchallenged,
especially among an informed public, indicate the value people associate with
trees. The following categories describe different values
that people place on trees. They are arranged primarily by their measurability.
The least measurable values are discussed first. Psychological and Aesthetic Values
Although difficult to gauge, uplifted spirits is one important benefit of
trees. Some of the difficulty in measuring these benefits may grow out of
society's decision to exclude tree values from the marketplace. Other
emotion-based commodities, such as flowers, perfume, view property, prestige
automobiles, and entertainment, are readily assigned monetary values. But with
proper treatment, researchers can tie monetary values to the emotional benefits
of trees. The pleasure and good feelings we associate with
trees may be far more practical than generally believed. Data on the connection
between vegetation and human health are beginning to accumulate. For example,
surgery patients who could see a grove of deciduous trees recuperated faster
and required less pain-killing medicine than matched patients who viewed only
brick walls. And, prisoners with cells overlooking green landscapes used prison
health facilities significantly less than prisoners whose cells provided views
of other prison facilities. The vaguely expressed "enjoyment" people
associate with trees may be partly a subconscious sign of substantial health
benefits. Social Values
In Oakland, California, a neighborhood tree planting program generated
community identity, cooperation, and benefits similar to those reported for
urban gardening. After coming together to plant trees, Oakland residents
continued working together with "paint-up-fix-up parties",
neighborhood protective societies, and community gardens. |
Historic Values
Trees provide important symbolic links with the past. If a living tree is
associated with important events, the tree takes on historical values unrelated
to aesthetics or usefulness. For example, a community would normally value a
tree that shaded the deliberations of the community's founders. A tree would
also be valuable if planted by George Washington or some other important figure
in history. Aside from specific events, old trees may be regarded as important
simply because they have lived through eras with which we have few other
connections.
As for emotional and aesthetic values, historic values of trees depend
primarily on community attitudes. If historic trees are threatened by changes,
such as new buildings and street widening, the issue will usually be settled by
public pressure not by market forces. |
Photo Credit - Lane County Museum, Eugene, Oregon,
First Christian Church, 1922. |
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Environmental Values
People value both the aesthetic and physical quality of our environment. Trees
contribute to this quality by modifying local climates, reducing noise and air
pollution, and by protecting soil and water. Climate control is one important service
trees provide naturally in the landscape, but the urban landscape is far from
natural. Streets, parking lots and buildings have changed the climate of urban
areas by absorbing solar radiation. Water that once percolated into the soil
and later evapotranspired from soil and plants now drains away or dries on the
hard surfaces. These changes have increased the temperatures of cities.
Compared to the surrounding rural areas, the urban "heat islands" are
five to nine degrees Fahrenheit warmer (three to five degrees Celsius).
Trees help moderate the "heat island" effect. They also greatly
increase human comfort: indoors or outdoors. On hot days, trees pump hundreds
of gallons of water through their foliage. This water evaporates, keeping the
tree and its immediate surroundings cool.
While groves of trees reduce local air temperatures, individual trees increase
human comfort primarily by controlling solar radiation, not air temperature.
(Radiation is the movement of heat from a warmer body, the Sun, to a cooler
body, the Earth.) Trees and other vegetation shield people from direct
sunlight. Trees also shade soil, pavement, buildings, and other surfaces that
would absorb solar energy and then radiate that heat back to the surroundings.
Without the protection of trees, city dwellers are literally surrounded by
radiant heat.
At night, radiation moves heat in the opposite direction: from the relatively
warm earth to the relatively cool sky. Again, tree cover steps in by blocking
radiant heat loss from homes and people. Icy mornings provide evidence of this
process, lawns otherwise white with frost often have green circles under the
trees.
Indoor air temperatures are also affected by trees growing around buildings.
During hot weather, trees reduce cooling costs by buffering high air
temperatures and blocking unwanted solar energy. But during winter months,
solar gain is desirable, because it cuts heating costs. To get the best
balance, on the south and west sides of buildings plant deciduous trees that
have thin, open branches to allow winter sun penetrate into the building. In
addition, the schedule of leaf growth and leaf drop should coincide with the
need for heating and cooling. Few, if any, species will meet these requirements
perfectly, but it's wise to select species that give the best possible match.
Air pollution control is another way that trees improve the
urban environment. The reductions in air pollution are modest, and air
pollution poses some risk to the trees themselves. |
Trees are fairly effective at
removing both solid and gaseous particulates from the air. In one study, stands
of trees reduced particulates by 9 to 13 percent, and the amount of dust
reaching the ground was 27 to 42 percent less under a stand of trees than in an
open area. Among gaseous pollutants, ozone, chlorine, fluorine, sulphur dioxide
and PAN (peroxyacetylnitrate, a photochemical component of smog) are all
absorbed by trees. In most cases, these gases also damage the trees.
Unfortunately, trees remove little, if any, carbon monoxide which amounts to
roughly one-half the total weight of air pollutants in this country. Increasingly, carbon dioxide is being recognized
as a "greenhouse gas" pollutant with potentially devastating
consequences, such as global warming, dramatic changes in rainfall patterns,
and rising sea levels that threaten flooding in coastal cities Since
photosynthesis in green plants consumes carbon dioxide, plants could help to
counteract the increase of this gas in the atmosphere. Rosenfeld, Martin, and
Rainer report that planting urban trees could reduce heating and cooling
demands enough to significantly cut fossil fuel consumption. They suggest that
urban trees could be about 10 times as effective as forest trees for lowering
carbon dioxide in cities. Noise pollution from highways and other sources can be reduced
with trees. Used alone, trees must be planted in belts 35 to 100 feet wide to
create noticeable reductions. However, earth berms can cut traffic noise by up
to half, if they are tall enough to hide the source of noise and are planted
with trees, shrubs, and grasses. Where this kind of adjustment to the
topography is not possible, a row of trees and a solid wall reaching up to the
base of the crowns will provide a similar reduction. |
First Christian Church, Eugene, Oregon, 1986.
Although these trees are protected under the Historic Tree Ordinance, it is a
tree that is no longer recommended for planting by the current administration
because of thorns. |
Soil and water quality are protected by
trees. In urban settings, large areas are covered by buildings, pavement, and
other impervious surfaces. Instead of percolating into the soil, rainwater and
snowmelt are concentrated and accelerated, increasing soil erosion and silt
accumulation in streams. Trees and other vegetation protect the soil from
erosion. Along watercourses, roots and fallen leaves help hold the soil
together and shield it against the cutting forces of surface water. Vegetation
also absorbs some of the force of failing rain, so soil particles are not
dislodged. And, the leaf litter that accumulates under trees creates an
environment for earthworms and other organisms that help maintain soil
porosity.
In studies at Pennsylvania State University, tracts of trees in municipal
watersheds were used to purify partly treated sewage and protect surface
waters. By adjusting sewage water application rates researchers prevented the
ground water from becoming contaminated with nitrates. Ninety percent of the
water applied went into recharging the underlying aquifer. Heavy metals, a
worrisome component of municipal sewage, did not become a problem. Monetary Values
Urban trees often have substantial monetary values. A number of studies have
shown that real estate agents and home buyers assign between 10 and 23 percent
of the value of a residence to the trees on the property. Local governments
capture some of this monetary value because enhanced property values increase
assessed values and the tax base. |
Appraisal methods have been
developed for landscape plants, including trees. The standard for estimating
the monetary value of landscape vegetation, usually accepted by insurance
companies, courts and public agencies, is Valuation of Landscape Trees,
Shrubs, and Other Plants: A Guide to the Methods and Procedures for Appraising
Amenity Plants. This guide was prepared by the Council of Tree and
Landscape Appraisers and published by the International Society of
Arboriculture, P.O. Box 71, Urbana, Illinois 61801. It is now in its seventh
edition. The guide describes two methods to estimate tree value.
The first method simply identifies the amount of money needed to replace the
tree. Replacement value can be used for trees less than or equal to eight
inches in diameter and commercially available in appropriate sizes. Adjust the
cost of the replacement tree for condition and location. Then add the cost of
planting and establishment, including labor, equipment, materials and
maintenance. Costs of guarantees and a reasonable profit margin could also be
added. If the purpose of the estimate is to settle a claim for the death or
damage of a tree, removal and cleanup costs for the dead or damaged tree are
also included. |
Technical competence and experience are required
for accurate tree valuations. |
The second method uses a formula
that multiplies the cross-sectional area of the trunk by a value (currently
$27) per square inch. It then adjusts this value for species, condition, and
location. Trees of different sizes are measured at various distances from the
ground. Tree diameter determines where the cross-sectional area is
measured. |
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Regardless of the method, determining the
adjustment factors for species, condition, and location requires technical
competence and experience. A tree valuation is only as credible as the arborist
who makes the determination.
The value of a particular species or variety can be looked up in an established
tree listings or judged by a local arborist. Value is often affected by local
usage.
Physical condition is also a factor' regardless of the kind or size of the
plant. Parts deformed by crowding, storm damage, fire, insect damage, disease
or other cause are primary concerns when judging condition. Careful inspection
should reveal these and other factors.
Plant location also affects value, especially when it is near buildings,
utility lines or other plants. Plants used in planned landscapes often have
higher appraised values than those growing wild.
Appraising a landscape plant requires considerable time on the site for looking
at the tree, its environment, measuring and examining its parts, collecting
samples, taking photo graphs, and asking questions of people living nearby. In
addition, the process requires decisions based on specialized knowledge of
plant pathology, aesthetics, ornamental horticulture, and tree physiology.
Appraisers often call on other experts for consultation in some of these areas.
Monetary value can also be assigned to some of the benefits trees bring to the
urban environment.
As mentioned earlier, sewage treatment costs could be cut by applying treated
effluent to trees and other landscape plantings. Irrigating with recycled waste
water reduces the need for costly evaporation ponds and sewage lagoons, as well
as the dumping of municipal wastes into rivers, lakes and oceans. And,
water-loving species could serve as natural water pumps for areas with high
water tables.
Trees can cut energy costs, too. Trees shade buildings and pavement, which
reduces the temperatures in and around buildings. By cutting air-conditioning
costs, trees indirectly reduce carbon dioxide emissions equivalent to fifteen
times the amount the tree alone could absorb. According to Akbari, et al.,
planting trees to reduce peak-load energy demand by one kilowatt-hour costs
about one cent.
Three well placed trees can cut air-conditioning costs by ten to fifteen
percent. For every ton of new wood that grows, about 1.8 tons of carbon dioxide
is removed from the air and 1 .3 tons of oxygen is produced. Reducing carbon
dioxide through tree planting costs about 0.3 to 1.3 cents per pound.
Akbari, et al., estimate that there are 100 million available tree planting
spaces around American homes and businesses. Planting trees in those spaces
could reduce atmospheric carbon dioxide by an estimated 18 million tons per
year, and save consumers $4 billion each year. |
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