IMPORTANCE OF HEALTHY
PLANTS TO THE TAMU CAMPUS
• There are many benefits from having a
healthy green environment on our campus.
• Most of the information that follows is
excerpted from many studies reported on the
internet.
• Although most references are to trees, other
vegetation would have similar benefits; either
increasing the effectiveness of the trees or
performing in ways and in places where trees
could not function.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Psychological benefits of a green environment:
• The importance of plants to our physiological
and psychological well being is probably a
greater benefit for Texas A&M University than all
of the other benefits listed in this paper, but it is
the most difficult to quantify.
• There is a growing body of research coming
from several fields that is now showing the
importance of natural green spaces in our daily
life.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Restorative Value of Nature:
• Trees and other plants deeply impact our moods
and emotions
• Visual exposure to settings with trees have
produced significant recovery from stress,
usually within five minutes, as indicated by
changes in blood pressure and muscle tension.
• Exposure to settings with trees and other plants
helps to reduce mental fatigue.
• Trees and other plants create feelings of
relaxation and well-being; provide privacy and a
sense of solitude and security.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Effects on Temperature
• A healthy population of trees, shrubs and other
vegetation produces a significant savings
– in the demand for utilities on campus
– in the cost of utilities
– in the amount of pollution caused by
generating power
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Trees and other vegetation have the following effects
on temperature:
• reduce the amount of power to air-condition buildings
in warm and hot weather
• reduce demand for energy to heat buildings in winter
• reduce the temperature on the walls and windows
that they shade from direct sunlight
• shade from trees reduces the temperature of a wall
by 15 degrees compared to a wall in direct sun
• reduce the surface temperature over sidewalks and
other hard surfaces: trees shading a parking lot can
reduce the temperature over exposed asphalt by as
much as 30 degrees
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Trees and other vegetation have the following
effects on temperature:
• reduce the peak air conditioning demand.
• help cool the “heat island” effect created by a
concentration of buildings and hard surfaces:
heat islands can be 3 to 10 degrees warmer than
surrounding areas
• leaves of trees and other plants transpire,
cooling themselves and to some extent their
surroundings
• collective effect of a large area of transpiring
trees reduces the air temperature in these areas
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Trees and other vegetation have the following
effects on temperature:
• shade from trees lowers the temperature making it much
more comfortable to be outside on a hot, sunny day
• the body's perception of the temperature on a hot, sunny
day (PET or Physiologically Equivalent Temperature) in
an "urban canyon" created by buildings was nearly 20
degrees cooler in the shade of trees than in the direct
sun; the actual difference in air temperature in the shade
and in the sun was approximately 3 degrees but the
effect of solar radiation directly striking the body made
the difference in perception of temperature. It also made
a reduction on a scale rating the body's response to
different temperatures from a situation of extreme heat
stress to moderate heat stress
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Trees and other vegetation have the following
effects on temperature:
• trees and large shrubs reduce the speed of the
wind and make it more comfortable on cold,
windy days in winter
• trees and large shrubs act as windbreaks in the
winter months, slowing the wind results in
savings in power for heating in winter
• plants make communities more livable for
people
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Storm Water:
• Trees, shrubs and other vegetation produce
significant indirect benefits when we consider
their impact on water and its movement.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Trees, shrubs and other vegetation impact storm
water management:
• reduces cost of storm water abatement needed to
comply with Clean Water Act: Storm Water Phase I
• reduces the amount of storm water running off
after a heavy rain
• slows the movement of water to allow more to soak
into the ground
• cleans the water
• reduces the amount of water running off hard
surfaces over which they are growing
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Trees, shrubs and other vegetation impact storm water
management:
• reduces the peak flow of water after a rain event
• reduces soil erosion and sedimentation of streams
• increases ground water recharge that is significantly
reduced by paving
• intercepts rainwater on leaves, branches, and trunks,
slowing movement into channelized drainage areas
• Diminishes storm water volume when some
intercepted water evaporates into the atmosphere
and some soaks into the soil
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Trees, shrubs and other vegetation impact storm
water management:
• the net reduction in total volume and peak flow
lessens the potential for flooding
• a USDA Forest Service study showed that a 28 ft.
tall tree intercepted 58.1 gallons of water or 68%
of a 1/2 inch rainfall event that fell within its crown
• intercept water and reduce the impact of rain
drops on the soil surface
• organic matter on the ground under trees keeps
the soil surface open, allowing more water to
penetrate into the soil and move downward
through the profile and reducing subsidence
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Trees, shrubs and other vegetation impact storm
water management
• The cost to construct storm water retention
basins is estimated at $2 per cubic foot of water
to be impounded.
• A study of Fayetteville, Arkansas, showed that
increasing tree canopy from 27% to 40% would
reduce their storm water runoff by 31%, a
savings of $43 million on capital improvements
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Greenhouse Effect:
• The greenhouse effect and its resultant
impact on global warming are caused by
accumulation of gasses in the air which trap
heat near the surface.
• Trees act as a carbon sink by removing the
carbon from carbon dioxide and storing it as
wood in their trunks and branches while
releasing oxygen back to the air.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Greenhouse Effect:
• A major study in Chicago showed that in a year's
time the trees in Chicago absorb the amount of
carbon dioxide produced by all forms of
transportation in a week. This studied indicated
that by increasing the planting of trees, the urban
forest of Chicago could absorb the carbon
emissions from all transportation for two months.
• The tree canopy over Dade County, Florida, is
estimated at 10% which sequesters approximately
5,245 tons of carbon annually, a benefit to the
county of $4.8 million.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Air Pollution:
• A brown haze can be seen when approaching the
Bryan / College Station area from the east in late
afternoon.
• The air pollution problem on campus is not as
great as the problem in Houston, but it is growing.
• We all need to play our part in reducing air
pollution.
• Trees and other vegetation reduce several types
of chemical air pollutants.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Air Pollution:
• Vegetation of all types reduces air pollution by
helping to settle out, trap and hold particulate
pollutants, such as dust, ash, pollen and
smoke that can damage human lungs
• Trees help reduce the production of ozone by
reducing air temperature through shading and
evapotranspiration
• Vegetation absorbs carbon dioxide, carbon
monoxide and other dangerous gases and, in
turn, replenishes the atmosphere with oxygen
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Air Pollution:
• A major study in Chicago estimated that trees in
that city annually removed
–
–
–
–
–
15 metric tons of carbon monoxide
84 metric tons of sulfur dioxide
89 metric tons of nitrogen dioxide
191 metric tons of ozone
212 metric tons of small particulates
• Studies have now been reported in several other
cities and all indicate significant benefits in
removal of pollutants by their urban forests.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Glare:
• Paved surfaces reflect a lot of light and cause a
problem with glare. This is especially noticeable
when walking over large paved surfaces such as
parking lots, but it is also noticed when walking
along many of the concrete walks on campus.
• Trees , turf and other plants are especially
effective in reducing glare on sunny days.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Noise:
• Noise pollution is especially
noticeable if one thinks of groups
meeting outdoors.
• Noise pollution on campus is caused
by traffic and the many mechanical
units located on buildings.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Noise:
• trees and other vegetation dampen or screen
out noise
• a row of healthy trees can cut the ambient noise
level by 50%
• noise reduction by trees does not block the
ground-level sight line as is done when berms of
soil are made and covered with turf
• plants mask the sharp sounds of mechanical
equipment by creating muted sounds of their
own, usually considered pleasant and soothing
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Aesthetics:
• An aesthetically attractive environment helps
all of us be more productive.
• The brief walk through the campus green
environment as we come to work can have
affect our attitude about our place of work; it
can help set the mood for a productive day.
• Having the opportunity to look out through
windows to a beautiful green environment is
especially pleasing and relaxing.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Aesthetics:
Trees and other plants do the following:
• Add beauty and function to the landscape
• Add natural character to our built spaces
• Provide us with colors, flowers, and beautiful
shapes, forms and textures
• Screen harsh scenery
• Soften the outline of masonry, metal and glass
• Provide space definition and landscape continuity
• Renew themselves
• Change with the seasons
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Aesthetics:
• Appearance of the campus ranks high among
the amenities that faculty members seek in
choosing a work place
• Appearance of the campus ranks high as a
factor in retention of faculty and staff
• Management of the green campus environment
should be exemplary
• The campus landscape should reflect the natural
ecosystem of Central Texas
• The campus landscape should draw new people
in, not turn them away
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Plants and Soil:
• Healthy plants and healthy soil work together.
• Healthy plants depend on effective soil management
but the effectiveness of soil in absorbing excess
water is related to plants growing on and in the soil.
• The benefits of healthy vegetation are reduced
significantly if methods of handling soil during
construction of new buildings, streets, underground
utilities, etc. is not changed and the topsoil restored.
• It is the topsoil, which has the greatest initial
capacity to soak up water and improve the health of
plants, is often reduced to a layer of an inch or two.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Plants and Soil:
• Topsoil can act as a water sink, soaking up
excess rain during rain events and releasing it
slowly over a period of days or weeks after the
rain event.
• To do this the soil must be permeable.
• Plants work together with soil in soaking up
water and slowing its movement into waterways
after a rain event.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Plants and Soil:
• one half of a good loamy topsoil is pore space
• one half of the soil’s pore space holds water and
one half holds air
• during a rain event the entire pore space can
hold water and release it slowly after the rain
event
• a shallow topsoil can absorb and hold only a
fraction of the rain that deep topsoil can hold
• a soil with impervious layers can not take on
water during a rain event nearly as well as a soil
that does not have an impervious layer
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Plants and Soil:
• Increasing the depth of the topsoil on the TAMU
campus by six inches would have enough pore
space to hold at least 2 inches of water during a
rain event or 7,260 cubic feet
• This would greatly reduce runoff.
• At the estimated cost of constructing storm water
catchment basins of $2 per cubic ft. of water, this
would save over $14,000 per acre.
• The effect would be greater if trees, shrubs,
ground covers, and other plants were planted in
the soil.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Wildlife Habitat:
• Trees and associated plants provide habitat and
food for birds and other animals.
• the lowest songbird diversity is in areas of mowed
turf
• highest bird diversity occurs in areas of large trees
• greater diversity in the types of trees is associated
with greater diversity in birds and other
• plantings of ornamental shrubs are associated with
greater numbers and diversity of birds
• highest populations of native birds occurs in areas
that have the highest percentage of native plants
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Diversifying trees on campus:
• The TAMU campus is an attractive over-wintering
habitat for a large flock of blackbirds.
• Evergreen trees are especially attractive for
nighttime roosts.
• Diversifying the trees on campus by adding more
types of deciduous trees would take away the winter
roosts but still provide the benefits of vegetation
listed above.
IMPORTANCE OF HEALTHY PLANTS
TO THE TAMU CAMPUS
Diversifying trees on campus:
• Deciduous trees would allow sunlight to come
into the campus at lower levels in winter,
warming the areas where benches are placed.
• Since the deciduous trees have a potentially
greater height than the evergreen live oaks this
would increase the depth of the canopy at times
of the year when trees have leaves for a greater
cooling effect.