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Dellview Elementary
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A 4-H after-school program, composed of 3rd, 4th and 5th graders from Dellview Elementary School in San Antonio, TX
was concerned that there were no trees behind their school that is adjacent to highly traveled US I-10 (figure 1).
They were troubled with excessive noise, air pollution, and lack of shade trees on their playground. Working with
Tom Fawcett, a 4-H volunteer leader, they learned about how trees can ameliorate these problems and improve the student
learning environment. The students used CITYgreen software, developed by American Forests, to model the benefits of
adding five red oak trees adjacent to I-10 and two cedar elms on the playground. The results of the analysis allowed
the students to make informed decisions regarding the benefits of the additional trees on their campus.
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Figure 1 - Dellview Elementary School
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The project enlisted the help of a tree expert to assist on the project. David Vaughan, an arborist from Etter Tree Care,
visited the group to teach them about the role trees play in the ecosystem and to properly inventory the 58 trees on school
grounds The students collected data about each tree’s diameter, canopy width, height, health, and growing conditions using
various tools, such as, tangent height gauge, measuring tape, and circumference tape. GPS receivers were used to record the
location of each tree so the data and their locations could be imported into the Geographic Information System (GIS) in their
computers.
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Back in the classroom, Fawcett worked with the students one-on-one, teaching them how to use ESRI's ArcView 3.3 GIS software
and the CITYgreen extension to determine the benefits of their trees (figure 2).
Some students excelled in using the software and were responsible for digitizing (digitally tracing) the impervious landcover
features from an aerial photo base map. Other students created a canopy data file that included the 58 trees and all of their
attributes collected in the field (figure 3).
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Figure 2 - CITYgreen in the lab |
Figure 3 - Digitized landcover |
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After the creation of the digital data, the students had the necessary information to input the data into CITYgreen and
perform an analysis of the landcover. The report generated by CITYgreen details the ecological and economic value of the
trees on the school campus. The students found that the trees on their campus are removing 105 pounds of air pollutants per
year with a value of $250 and are storing 54 tons of carbon. CITYgreen also allowed the students to model the planting of
five additional red oak trees in the area next to US I-10 and two cedar elms on the playground. The students digitally added
the new trees to their canopy tree data and ran the analysis again (figure 4).
The report shows a slight increase of an additional 1 pound of air pollutants removed annually. Next the students modeled
the growth of all of the trees on the school’s campus over a period of 25 years (figure 5).
The increase in tree canopy over the 25 year period shows an increase of 53 pounds of air pollutants removed annually and
an increase in the amount of carbon stored in its biomass by 27 tons (table 1). Comparing the numbers, the students learned
that the actions they today by planting additional trees on their campus will have lasting environmental benefits long into
the future. |
Figure 4 - Seven new trees added |
Figure 5 - Trees modeled 25 years |
Table 1 - Ecosystem Services of Trees by Canopy Models
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Canopy
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Air Pollution
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Carbon
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%
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Pounds Removed Annually
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$ Value Annually
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Tons Stored
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Current Conditions
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10%
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105
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$250
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54
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With 7 New Trees
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10%
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106
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$253
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54
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25 Years Later
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15%
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159
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$379
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81
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The students presented their work via a powerpoint presentation to fellow students, teachers, parents, and school administrators
on May 19th, the school’s GIS day. The students communicated that an increase in tree canopy on their school campus can have a
lasting impact on the overall health of the community by reducing air pollution, storing atmospheric carbon and providing shade
to the playground. Although the five red oak and two cedar elm trees have not been planted due to lack of funding, the students
have the knowledge and tools to push decision-makers to consider effective planning practices on their school campus.
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