Environmental Benefits Analysis for Trees in Bowersville, Ohio

T. Davis Sydnor and Sakthi Subburayalu School of Environment and Natural Resources

as well as Greene County Master Gardeners Ohio State University Extension

 

June 8, 2011

 

 

2 

 

An Analysis of Tree Benefits for Bowersville, Ohio

EXECUTIVE SUMMARY An inventory of public trees on the streets and in the parks of the Village of Bowersville, Ohio was conducted by Ohio State Extension and its Greene County Master Gardeners in 2010. A total of 89 trees were inventoried during this period. A common bid price for this service is $4.00 per tree and thus the inventory represents a value of $360. Most importantly, however, is that the community now has a tree inventory in a form that can be used to better manage the tree resource of Bowersville. Benefits mentioned above do not include the value of the subsequent analysis and report by The Ohio State University’s School of Environment and Natural Resources which would conservatively add another $11,500. Analysis of the inventory data was done using iTree, a software suite distributed by the USDA Forest Service. The specific program in the iTree suite used to identify benefits was iStreets. This program allows community leaders interested in making informed decisions about Bowersville’s green infrastructure or to explore many aspects including biodiversity and values of environmental services such that environmental benefits can be enhanced to reduce costs and the carbon footprint of Bowersville. A long standing rule of thumb for taxonomic biodiversity is the 10–20–30 guideline which suggests that no more than 10 percent of trees should be from the same species, no more than 20 percent should be from the same genera, and no more than 30 percent should be from the same family. In Bowersville, Callery pear and maple exceed one or more guidelines (Table 1). We would recommend against any further plantings of Callery pear and maple until guidelines are met. No more ash should be planted because of emerald ash borer (EAB) and represents 8 individuals or 9% of the public trees and 15 % of the canopy (Table 4). This will represent a noticeable loss of canopy if EAB should destroy all American ash as predicted. Ash removal and/or treatment costs will need to be addressed by informed community leaders. Ohio State Extension can assist in developing considered plans including costs and probabilities of treatment vs. no treatment. There is no single answer for communities facing this problem. Based on the inventory and an earlier study, ash removal costs in Bowersville would cost nearly 10,000 dollars with replacement costs adding another $2,000 for total costs over $12,000.

Larger growing deciduous trees constituting 2% or less of Bowersville’s canopy cover that could be used to replace the ash, pears and maples include the Kentucky coffeetree; Shumard, swamp white, and chinquapin oaks; American sycamore, buckeye, basswood, zelkova, and honeylocust.

Under ideal conditions tree numbers among various size classes should be stable and then decline as trees reach their mature size and older trees die. Bowersville generally has spikes of even aged trees. Pears and maples are concentrated in mature sizes and may represent a maintenance concern as they tend to be structurally instable.

Table 4 shows that the 22 maples produce a larger percentage of canopy cover than smaller growing pears. This reinforces the need for planting larger statured trees such as preferred in a Toledo, OH resident preference survey whenever possible although maples should be avoided for biodiversity. The importance value is a measure of the overall contribution of the species to the sum of environmental benefits delivered.

A major benefit of urban trees is their ability to intercept rainfall and reduce storm water runoff (Table 5). Storm water runoff is a major cost for Ohio communities. Columbus, OH is embarking on a multi-billion dollar sewer and

 

3 

 

storm water upgrade for the community. Public trees, alone, in Bowersville intercept nearly 100,000 gallons of storm water annually at a savings to the community of almost $2,700 dollars per year. This could be increased with strategic plantings of larger growing trees and given time for them to reach maturity.

Carbon sequestration, as reported here, represents the carbon removed from the air and stored in the trees (Table 6). More than 305,000 pounds or 153 tons of carbon have been stored by the 89 trees over time. Bowersville’s trees

currently sequester and avoid 34,000 lbs of CO2 yearly (Table 8) and would represent carbon credits worth $259 per year if a carbon trading system were in place and if a system for accounting for them were available for community trees. These are net gain figures and include deductions for tree losses and maintenance. Annual CO2 benefits vary by species and size but average $2.92 per tree per year while the larger boxelder average $16.84 per tree per year or more than five times as much. Strategic plantings of larger trees could increase this substantially and be a significant tool in reducing Bowersville’s carbon footprint if desired.

Energy savings by trees are particularly important in view of the citizenry’s increasing concern over the nation’s energy dependency. Energy is saved by shading structures, evaporating water (evapotranspiration) and reducing wind speed around structures (Table 7). Bowersville’s trees save the community nearly $1,000 in electricity and nearly $3,000 in natural gas for a total savings of $2,874 or an average of $32 per tree per year. Again, larger statured trees to enhance energy savings and have real potential as trees mature.

Annual air quality savings (reduced ozone, nitrous and sulfur oxides as well as particulate matter) for the public trees is nearly $500 (Table 9). This includes both direct savings ($110) from Bowersville’s trees and avoided pollution which is nearly $400. Avoided pollution is pollution not generated at power source because energy was not required (avoided) by the community. The total annual air quality benefits are discounted by $5 for the volatile emissions (BVOC) from the trees themselves. While these savings are small the impact depends on whether or not individuals have a condition such as asthma which renders them sensitive to air pollutants such as dust (PM10).

Aesthetic and miscellaneous benefits from trees contribute nearly $1,300 annually to Bowersville in the form of increased property values and enhanced community identity among other things (Table 10). Research in public housing has shown that areas with trees facilitate interaction among residents and lead to reduced domestic violence and more sociable environments. Customer surveys suggest that customers prefer to spend their money and time in commercial streetscapes with trees and are willing to spend up to 11% more in such an environment.

When all benefits are included the 89 trees contribute an average of nearly $106 per tree annually to the village’s community (Table 11). Species vary in their annual benefits but mature size, longevity, and maintenance costs are but some of the factors determining annual benefits. This would be well in excess of their maintenance and planting costs for Bowersville’s trees.

The Bowersville budget for trees maintenance was estimated to be $580 based on the budget of $2 per capita required for Tree City USA status by the National Arbor Day Foundation and Bowersville’s population of 290. Thus while the 89 trees on the grounds require relatively little care per year they deliver $7,600 in annual benefits from storm water abatement, carbon sequestration, energy savings, air quality, aesthetic benefits, and the like. This is more than a 1300% return on investment. Returns are likely high but Ohio communities studied routinely discover returns of 2-300% on their tree maintenance dollars and Toledo had a 436% annual return with one of the larger tree maintenance budgets in Ohio. Further, unlike most community infrastructure, annual tree benefits per tree continue to increase over a tree’s lifetime especially as trees are allowed to mature.

 

4 

 

Table 1. Species Distribution of the Most Common Trees in Bowersville, Ohio Arranged from Most to Least Commonly Seen

Species  Percent 

Pear   52.81  

Maple   24.72  

Ash   8.99  

Black walnut   5.62  

Flowering crabapple   3.37  

Eastern redbud   2.25  

Boxelder   1.12  

Pine   1.12  

OTHER SPECIES   0.00  

Total   100.00  

 

5 

 

Table 2. Relative Age Distribution of the 10 Most Commonly Planted Trees in Bowersville as a Percentage (%) of each Tree by Common Names

Species  Diameter at Brest Height (in) 

3‐6  6‐12  12‐18  18‐24  24‐30  30‐36  36‐42  >42 

Pear  4.3  93.6  2.1  0.0  0.0  0.0  0.0  0.0 

Maple  4.5  9.1  18.2  4.5  40.9  18.2  4.5  0.0 

Ash  0.0  0.0  62.5  0.0  0.0  0.0  0.0  37.5 

Black walnut  0.0  20.0  0.0  80.0  0.0  0.0  0.0  0.0 

Flowering crabapple  66.7  33.3  0.0  0.0  0.0  0.0  0.0  0.0 

Eastern redbud  0.0  100.0  0.0  0.0  0.0  0.0  0.0  0.0 

Boxelder  0.0  0.0  0.0  0.0  0.0  0.0  100.0  0.0 

Pine  0.0  100.0  0.0  0.0  0.0  0.0  0.0  0.0 

Bowersville total  5.6  57.3  11.2  5.6  10.1  4.5  2.2  3.4 

 

6 

 

Table 3. Population of Bowersville Trees by Common Name, Tree Type and Size (DBH) Class.

Species DBH Class (in) 

3‐6  6‐12  12‐18  18‐24  24‐30  30‐36  36‐42  >42  Total 

Broadleaf Deciduous Large (BDL)                      

Maple   1    2    4    1    9    4    1    0   22  

Black walnut   0    1    0    4    0    0    0    0    5  

Total   1    3    4    5    9    4    1    0    27  

     

Broadleaf Deciduous Medium (BDM)    

Ash   0    0    5    0    0    0    0    3    8  

Boxelder   0    0    0    0    0    0    1    0    1  

Total   0    0    5    0    0    0    1    3    9  

     

Broadleaf Deciduous Small (BDS)    

Callery Pear   2    44    1    0    0    0    0    0   47  

Flowering crabapple   2    1    0    0    0    0    0    0    3  

Eastern redbud   0    2    0    0    0    0    0    0    2  

Total   4    47    1    0    0    0    0    0    52  

     

Conifer Evergreen Large (CEL)    

Pine   0    1    0    0    0    0    0    0    1  

Total   0    1    0    0    0    0    0    0    1  

                             

Bowersville Total   5    51    10    5    9    4    2    3    89  

 

7 

 

Table 3A Estimated Expenses for Ash Removal and/or Replacement for Bowersville Street Trees due to Emerald Ash Borer SIZE  NUMBER 

REMOVAL COSTS PER TREE 

REMOVAL TOTALS 

REPLACEMENT COST REMOVAL W/ REPLACEMENT 

1‐3  0  $375   $0   $290   $0  

3‐6  0  $375   $0   $290   $0  

6‐12  0  $375   $0   $290   $0  

12‐18  5  $675   $3,375   $290   $4,825  

18‐24  0  $675   $0   $290   $0  

24‐30  0  $1,290   $0   $290   $0  

30‐36  0  $1,625   $0   $290   $0  

36‐42  0  $2,150   $0   $290   $0  

>42  3  $2,150   $6,450   $290   $7,320  

TOTALS    REMOVAL ONLY 

TOTALS $9,825  

REMOVE + REPLACE TOTALS 

$12,145  

 

8 

 

Table 4. Bowersville, Ohio Trees Listed by Common Name from Greatest to Least Importance Value.

Species Number of Trees 

% of Total Trees 

Leaf Area (ft2) 

% Total Leaf Area 

Canopy Cover (ft2) 

% Total Canopy Cover 

Importance Value 

Maple  22  24.7  81271  54.4  26581  44.8  41.3 

Callery pear  47  52.8  10423  7.0  14769  24.9  28.2 

Ash  8  9.0  27516  18.4  8877  15.0  14.1 

Black walnut  5  5.6  18777  12.6  5975  10.1  9.4 

Boxelder  1  1.1  10119  6.8  1716  2.9  3.6 

Flowering crabapple  3  3.4  289  0.2  505  0.9  1.5 

Eastern redbud  2  2.2  436  0.3  632  1.1  1.2 

Pine  1  1.1  690  0.5  238  0.4  0.7 

Total  89  100.0  149522  100.0  59293  100.0  100.0 

 

9 

 

Table 5. Annual Storm Water Benefits of Bowersville, Ohio Trees by Species Ordered by Decreasing Benefits/Tree

Species 

Total Rainfall 

Interception (Gal) 

Total ($) 

% of Total Tree 

Numbers 

% of Total $ 

Avg. $/tree 

Boxelder  5044  $136.70  1.1  5.1  $136.70 

Black walnut  11548  $312.99  5.6  11.6  $62.60 

Maple  50805  $1,376.90  24.7  51.0  $62.59 

Ash  18337  $496.97  9.0  18.4  $62.12 

Pine  595  $16.14  1.1  0.6  $16.14 

Pear  12441  $337.16  52.8  12.5  $7.17 

Eastern redbud  529  $14.34  2.3  0.5  $7.17 

Flowering crabapple  402  $10.89  3.4  0.4  $3.63 

BOWERSVILLE TOTAL  99701  $2,702.08 100.0  100.0  $30.36 

 

10 

 

Table 6. Stored CO2 Benefits in the Trees in Bowersville, Ohio by Species and Ordered by Decreasing Benefits per Tree

Species Total 

stored CO2 (lbs) 

Total ($) % Total Tree 

Numbers

% of Total $ 

Avg. $/tree 

Boxelder  33674  $252.56  1.1  11.0  $252.56 

Ash  60961  $457.21  9.0  20.0  $57.15 

Maple  136096  $1,020.72  24.7  44.6  $46.40 

Black walnut  27879  $209.09  5.6  9.1  $41.82 

Pear  43341  $325.05  52.8  14.2  $6.92 

Eastern redbud  1816  $13.62  2.3  0.6  $6.81 

Flowering crabapple  1263  $9.48  3.4  0.4  $3.16 

Pine  257  $1.93  1.1  0.1  $1.93 

CITYWIDE TOTAL  305287  $2,289.65 100.0  100.0  $25.73 

 

11 

 

Table 7. Annual Energy Benefits of Bowersville, Ohio Trees by Common Name and Decreasing Energy Benefits/Tree

Species Total 

Electricity (MWh) 

Electricity ($) 

Total Natural Gas 

(Therms) 

Natural Gas ($) 

Total ($) 

% Total Tree 

Numbers 

% of Total $ 

Avg. $/tree 

Boxelder  0.3  $24.41  44.3  $43.37  $67.78  1.1  2.4  $67.78 

Ash  2.1  $162.48  289.7  $283.92  $446.40  9.0  15.5  $55.80 

Black walnut  1.2  $93.30  178.7  $175.16  $268.45  5.6  9.3  $53.69 

Maple  5.5  $421.24  757.0  $741.82  $1,163.06  24.7  40.5  $52.87 

Eastern redbud  0.1  $11.24  25.7  $25.15  $36.39  2.3  1.3  $18.19 

Pear  3.5  $264.51  596.9  $584.92  $849.43  52.8  29.6  $18.07 

Pine  0.1  $4.27  9.5  $9.31  $13.58  1.1  0.5  $13.58 

Flowering crabapple  0.1  $8.98  20.4  $20.02  $29.00  3.4  1.0  $9.67 

BOWERSVILLE TOTAL  13.0  $990.43  1922.1  $1,883.65  $2,874.08  100.0  100.0  $32.29 

 

 

 

Table 8. Annual Carbon Dioxide Benefits of Bowersville, Ohio Trees by Common Name and Ordered by Decreasing Benefits per Tree

Species Sequestered 

(lb) Sequestered 

($) Decomp 

Release(lb) Maintenance Release (lb) 

Total Release 

($) 

Avoided (lb) 

Avoided ($) 

Net Total (lb) 

Total ($) % Total Tree 

Numbers 

% of Total $ 

Avg. $/tree 

Boxelder  1872  $14.04  ‐161.6  ‐5.1  ‐$1.25  539.4  $4.05  2245.2  $16.84  1.12  6.5  $16.84 

Black walnut  1479  $11.09  ‐133.8  ‐12.1  ‐$1.09  2061.8  $15.46  3395.2  $25.46  5.62  9.8  $5.09 

Ash  1930  $14.47  ‐292.6  ‐22.6  ‐$2.36  3590.8  $26.93  5205.3  $39.04  8.99  15.0  $4.88 

Maple  3225  $24.19  ‐653.3  ‐51.7  ‐$5.29  9309.3  $69.82  11829.8  $88.72  24.72  34.2  $4.03 

Pear  5354  $40.15  ‐208.0  ‐54.6  ‐$1.97  5845.6  $43.84  10937.0  $82.03  52.81  31.6  $1.75 

Eastern redbud  228  $1.71  ‐8.7  ‐2.3  ‐$0.08  248.3  $1.86  465.0  $3.49  2.25  1.3  $1.74 

Pine  53  $0.39  ‐1.2  ‐1.2  ‐$0.02  94.4  $0.71  144.6  $1.08  1.12  0.4  $1.08 

Flowering crabapple  190  $1.42  ‐6.1  ‐2.3  ‐$0.06  198.5  $1.49  379.9  $2.85  3.37  1.1  $0.95 

BOWERSVILLE TOTAL  14331  $107.48  ‐1465.4  ‐151.9  ‐$12.13  21888.3  $164.16  34602.0  $259.51  100.00  100.0  $2.92 

 

13 

 

Table 9. Annual Air Quality Benefits of Bowersville, Ohio Trees by Species’ Common Names and Ordered by Decreasing Total Air Pollution Benefits per Tree

Species Deposition O3 (lb) 

Deposition NO2 (lb) 

Deposition PM10 (lb) 

Deposition SO2 (lb) 

Total Deposition 

($) 

Avoided NO2 (lb) 

Avoided PM10 (lb) 

Avoided VOC (lb) 

Avoided SO2 (lb) 

Total Avoided 

($) 

BVOC Emissions 

(lb) 

BVOC Emissions 

($) 

Total (lb) 

Total ($) 

% of Total Tree 

Numbers 

Avg. $/tree 

Boxelder  0.79  0.13  0.35  0.04  $4.13  1.53  0.22  0.21  1.46  $9.56  ‐0.18  ‐$0.66  4.55  $13.03  1.12  $13.03 

Ash  3.69  0.64  1.82  0.16  $19.94  10.21  1.49  1.42  9.71  $63.67  ‐0.87  ‐$3.26  28.27  $80.34  8.99  $10.04 

Maple  12.69  2.16  5.86  0.56  $67.42  26.44  3.85  3.67  25.14  $164.81  ‐4.19  ‐$15.71  76.19  $216.52  24.72  $9.84 

Black walnut  0.98  0.17  0.58  0.04  $5.59  5.96  0.86  0.82  5.57  $36.92  0.00  $0.00  14.99  $42.51  5.62  $8.50 

Pear  2.22  0.36  1.27  0.10  $12.44  17.70  2.50  2.37  15.79  $107.61  ‐0.01  ‐$0.05  42.29  $119.99  52.81  $2.55 

Eastern redbud  0.09  0.01  0.05  0.00  $0.51  0.75  0.11  0.10  0.67  $4.58  0.00  $0.00  1.79  $5.09  2.25  $2.55 

Pine  0.05  0.01  0.05  0.01  $0.37  0.28  0.04  0.04  0.25  $1.73  ‐0.17  ‐$0.62  0.57  $1.48  1.12  $1.48 

Flowering crabapple  0.05  0.01  0.03  0.00  $0.31  0.60  0.08  0.08  0.54  $3.66  0.00  $0.00  1.40  $3.97  3.37  $1.32 

BOWERSVILLE TOTAL 

20.56  3.49  10.02  0.92  $110.70  63.48  9.16  8.71  59.14  $392.53  ‐5.42  ‐$20.31  170.07  $482.92  100.00  $5.43 

 

 

Table 10. Annual Aesthetic or Other Benefits of Trees by Species in Bowersville, Ohio

Species 

% of Total Tree 

Numbers 

% of Total $ 

Total ($) Avg. $/tree 

Boxelder  1.12  7.36  $95.34  $95.34 

Black walnut  5.62  17.29  $223.89  $44.78 

Ash  8.99  15.12  $195.80  $24.48 

Maple  24.72  33.96  $439.62  $19.98 

Pine  1.12  1.19  $15.42  $15.42 

Pear  52.81  23.27  $301.29  $6.41 

Eastern redbud  2.25  0.99  $12.80  $6.40 

Flowering crabapple  3.37  0.81  $10.52  $3.51 

CITYWIDE TOTAL  100.00  100.00  $1,294.69 $14.55 

 

 

15 

 

Table 11. Annual Benefits and Total Annual Benefits per Tree by Common Name for Bowersville Street Trees

Species  Energy  CO2 Air 

Quality Stormwater Aesthetic/Other  Total 

Boxelder  $67.78  $16.84  $13.03  $136.70  $95.34  $329.68

Black walnut  $53.69  $5.09  $8.50  $62.60  $44.78  $174.66

Ash  $55.80  $4.88  $10.04  $62.12  $24.48  $157.32

Maple  $52.87  $4.03  $9.84  $62.59  $19.98  $149.31

Pine  $13.58  $1.08  $1.48  $16.14  $15.42  $47.70 

Eastern redbud  $18.19  $1.74  $2.55  $7.17  $6.40  $36.05 

Pear  $18.07  $1.75  $2.55  $7.17  $6.41  $35.96 

Flowering crabapple  $9.67  $0.95  $1.32  $3.63  $3.51  $19.07 

 

16 

 

Table 12 Environmental Benefits from Five Benefit Categories for Bowersville Street Trees

Benefits  $/tree Total ($) 

    Energy  $32.29  $2,874 

    Stormwater  $30.36  $2,702 

    Aesthetic/Other  $14.55  $1,295 

    Air Quality  $5.43  $483 

    CO2  $2.92  $260 

Total Benefits  $85.55  $7,614