- Most trees and shrubs in cities or
communities are planted to provide beauty or shade. These are two excellent
reasons for their use. Woody plants also serve many other purposes, and it
often is helpful to consider these other functions when selecting a tree or
shrub for the landscape. The benefits of trees can be grouped into social,
community, environmental and economic categories.
- We like trees around us because they make life more pleasant. Most of us
respond to the presence of trees beyond simply observing their beauty. We feel
serene, peaceful, restful and tranquil in a grove of trees. We are "at home"
there. Hospital patients have been shown to recover from surgery more quickly
when their hospital room offered a view of trees. The strong ties of people
and trees are most evident in the resistance of community residents to
removing trees to widen streets. Or we note the heroic efforts of individuals
and organizations to save particularly large or historic trees in a community.
The stature, strength, and endurance of trees give them a cathedral-like
quality. Because of the potential for long life, trees are frequently planted
as living memorials. We often become personally attached to trees that we or
those we love have planted .
- Even though trees may be private property, their size often makes them
part of the community as well. Since trees occupy considerable space, planning
is required if both you and your neighbors are to benefit. With proper
selection and maintenance, trees can enhance and function on one property
without infringing upon the rights and privileges of neighbors.
City trees often serve several architectural and engineering functions.
They provide privacy, emphasize views or screen out objectionable views. They
reduce glare and reflection. They direct pedestrian traffic. They provide
backgrounds, or soften, complement or enhance architecture.
Trees bring natural elements and wildlife habitats into
urban surroundings; all of which increase the quality of life for residents of
- Trees alter the environment in which we live by moderating climate,
improving air quality, conserving water and harboring wildlife. Climate
control is obtained by moderating the effects of sun, wind, and rain. Radiant
energy from the sun is absorbed or deflected by leaves on deciduous trees in
the summer and is only filtered by branches of deciduous trees in winter. We
are cooler when we stand in the shade of trees and are not exposed to direct
sunlight. In winter, we value the sun's radiant energy; and because of this,
we should plant only small or deciduous trees on the south side of homes. Wind
speed and direction can be affected by trees. The more compact the foliage on
the tree or group of trees, the greater the influence of the windbreak. The
downward fall of rain, sleet and hail is initially absorbed or deflected by
trees and this provides some protection for people, pets and buildings. Trees
intercept water, store some of it, reduce storm run-off and the possibility of
flooding. Dew and frost are less common under trees because less radiant
energy is released from the soil in those areas at night.
Temperature in the vicinity of trees is cooler than
that away from trees. The larger the tree, the greater the cooling. By using
trees in the cities, we are able to moderate the heat island effect caused by
pavement and buildings in commercial areas.
Air quality can be improved through the use of trees, shrubs and turf. Leaves
filter the air we breathe by removing dust and other particulates. Rain washes
the pollutants to the ground. Leaves absorb carbon dioxide from the air to form
carbohydrates that are used in the plant's structure and function. In this
process, leaves also absorb other air pollutants such as ozone, carbon monoxide,
and sulfur dioxide, and give off oxygen.
By planting trees and shrubs, we return to a more natural, and less
artificial environment. Birds and other wildlife are attracted to the area. The
natural cycles of plant growth, reproduction and decomposition are again
present, both above and below ground. Natural harmony is restored to the urban
- Property values of landscaped homes are 5-20% higher than
those of non-landscaped homes.
Individual trees and shrubs have value, but the variability of species,
size, condition and function makes determining their economic value quite
difficult. The economic benefits of trees can be both direct and indirect.
Direct economic benefits are usually associated with energy costs. Air
conditioning costs are lower in a tree-shaded home. Heating costs are reduced
when a home has a windbreak. Trees increase in value from the time they are
planted until they mature. Trees are a wise investment of funds since
landscaped homes are more valuable than non-landscaped homes. The savings in
energy costs and the increase in property value directly benefit each
The indirect economic benefits of trees are even greater. These are
available to the community or region. Lowered electricity bills are paid by
customers when power companies are able to use less water in their cooling
towers, build fewer new facilities to meet peak demands, use reduced amounts
of fossil fuel in their furnaces and need fewer measures to control air
pollution. Communities can also save if fewer facilities must be built to
control storm water in the region. To the individual these savings are small,
but to the community, reductions in these expenses are often in the thousands
Trees Require an
- Trees provide numerous aesthetic and economic benefits but also incur some
costs. You need to be aware that an investment is required for your trees to
provide the benefits that you desire. The biggest cost of trees and shrubs
occurs when they are purchased and planted. Initial care almost always
includes some watering. Leaf, branch and whole tree removal and disposal can
To function well in the landscape, trees require maintenance. Much can be
done by the informed homeowner. Corrective pruning and mulching will give
trees a good start. Shade trees, however, quickly grow to a size that may
require the services of a professional arborist. Arborists have the knowledge
and equipment needed to prune, spray, fertilize and otherwise maintain a large
tree. Your garden center owner, cooperative extension agent, community
forester or consulting arborist can answer questions about tree maintenance,
suggest treatments or recommend qualified arborists.
The PHC Alternative
- Maintaining mature landscapes is a complicated undertaking. You may wish
to consider a professional Plant Health Care (PHC) maintenance program which
is now available from many landscape care companies. Their program is designed
to maintain plant vigor and should initially include inspections to detect and
treat any existing problems which could be damaging or fatal. Thereafter,
regular inspections and preventive maintenance will ensure plant health and
beauty. Refer to our Plant Health Care brochure for more information.
- This brochure is one in a series published by the
International Society of Arboriculture as part of its Consumer Information
Program. You may have additional interest in the following titles currently in
the series: Insect and
Disease Problems; Mature Tree
Care; New Tree
Planting; Trees and
Turf; Benefits of
Selection; Plant Health
Care; Avoiding Tree
and Utility Conflicts; Recognizing
Tree Hazards; Why Hire an
High-Quality Trees; Tree
Values; Pruning Young
Mature Trees; Why Topping
Hurts Trees; Pruning Young
Mature Trees; Avoiding
Tree Damage During Construction; Treatment of
Trees Damaged by Construction.
Developed by the International Society of Arboriculture (ISA), a non-profit
organization supporting tree care research around the world and dedicated to
the care and preservation of shade and ornamental trees. For further
information, contact: ISA, P.O. Box 3129, Champaign, IL 61826-3129, USA.
© 1995 International Society
UPDATED FEBRUARY 2000