Transcript Size Distribution Across DBH Class for Large Trees

Analysis of Ecosystem Services Provided by Street Trees
on the Indiana University-Bloomington Campus
Kaitlyn McClain, School of Public and Environmental Affairs
Introduction
Methods (Continued)
Results (Continued)
Trees found on the Indiana University-Bloomington
(IUB) grounds provide many valuable ecosystem
services to the campus such as reductions in CO2,
energy costs, and stormwater runoff. Only a
healthy, sustainable street tree population will
provide these benefits to IUB’s students, faculty, and
staff.
Correct
The inventory analysis
indicates that only 32
percent of young trees
were mulched correctly,
while 68 percent of
young
trees
were
mulched incorrectly .
Incorrect
32%
68%
Figure 5: Proportion of correct
and incorrect mulching in young
trees (DBH ≤ 2” class)
In this study, I quantify the costs and benefits of the
campus’
street
trees,
evaluate
species
demographics, and offer recommendations for
future management practices by executing a
sample streetscape analysis using the i-Tree Streets
software application.
This sample streetscape
inventory fills a gap in existing data and provides a
baseline for further research.
Benefits
Figure 1: Map of streetscape segments sampled on the IUB campus
Total ($)
Energy
Results
Streetscape Inventory Species Population Summary
Standard Error
Total
$/tree
Standard Error Per
Tree
2,548
(±195)
3.19
(±.24)
CO2
440
(±34)
0.55
(±.04)
Air Quality
896
(±68)
1.12
(±.09)
7,591
(±580)
9.51
(±.73)
23,810
(±1,819)
29.84
(±2.28)
35,285
(±2,695)
44.22
(±3.38)
Stormwater
50
Aesthetic/Other
45
Methods
Field data collection took place on March 15, 18,
and 25, 2012. All field data, with the exception of
the additional data pertaining to young trees (DBH ≤
2” class), was recorded electronically on an HP iPAQ
PDA. Tree data collected included location, species,
diameter at breast height (DBH), condition, and
wire or sidewalk conflicts.
Total Benefits
35
Number of Trees
The core of the IUB campus was divided into 74
0.1mi street segments. A random 20 percent of the
segments were sampled to obtain data about IUB’s
streetscape (See Figure 1). The streetscape
boundary for this study extended from the street
curb to the front of a building or extended 50ft from
the street curb if no building was present.
40
Total Costs
30
20
Total Costs Adjusted
15
Net Benefits
10
29,472
36.93
5,813
(±2,695)
7.29
(±3.38)
Table 1: i-Tree Streets net benefit summary, 2012 streetscape inventory
5
0
Red maple
Silver maple
Oak
Other
Sugar maple
Broadleaf Deciduous
Small
Broadleaf Deciduous
Large
Broadleaf Deciduous
Medium
Unknown
Dogwood
Fir
Braodleaf Evergreen
Large
Chinkapin oak
Maple
The net benefits of the inventoried trees can be
found in Table 1. The total costs were reduced to 20
percent of the original value to reflect the 20
percent sample size. The analysis shows that the
IUB streetscape provides positive net benefits.
Stump
Tree Species
Figure 2: Species population summary, 2012 streetscape inventory
Figure 2 depicts the population summary of the streetscape inventory. There were over 21 different species
recorded. The three most dominant species being Red maple, Silver maple, and various oak species.
Size Distribution Across DBH Class for Large Trees
Size Distribution Across DBH Class for Small Trees
35
Recommendations
9
30
8
7
25
Number of Trees
Number of Trees
5
4
20
15
3
10
2
5
1
Data analysis was performed by using i-Tree Streets’
“Report” tool. Reports were generated from the
uploaded tree records. Young tree data was
analyzed in Microsoft Excel.
184.66
25
6
At the end of each data collection session, field data
was transferred from the PDA to i-Tree Streets.
Young tree data was recorded by hand on paper and
uploaded manually into Microsoft Excel.
147,361
0
0-2
2-4
4-6
6-8
8-10
10-12
12-14
14-16
16-18
DBH Class (in)
Figure 3: Small tree DBH distribution, 2012 streetscape inventory
Figure 3 depicts the distribution of small tree species
across DBH size classes. The small tree species are
distributed unevenly. The number of younger trees is
much larger than the number of older trees. There
are only two trees larger than the 6-8in class.
0
0-2
2-4
4-6
6-8
8-10
10-12
12-14
14-16
16-18
DBH Class (in)
Figure 3: Large tree DBH distribution, 2012 streetscape inventory
Figure 4 depicts the distribution of large tree species
across DBH size classes. The large tree species are
distributed unevenly. There are more younger trees
and far less older trees recorded in the inventory. The
noticeable dip starts at the 6-8in class.
• Increase tree plantings of varied native
deciduous tree species to reach the canopy
cover goal by 2020
• Implement a planting plan to address the
uneven age distribution of trees to avoid large
losses in canopy cover as older trees are lost in
the coming years
• Properly train maintenance workers in mulching
techniques to prevent problems associated with
incorrect mulching of young trees
Acknowledgements
I would like to thank graduate student Matt Patterson
for his help in conducting the i-Tree Streets analysis
and Professor Burney Fischer for his continued
guidance during every step of the Spring 2012 Honors
thesis research process.