Edmond Urban Tree Canopy Report U r ba n for e st ry depa rt me n t, 2012
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Edmond Urban Tree Canopy Report U r ba n for e s t ry depa rt me n t, 2012
ta bl e of con t e n ts
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2 Edmond’s Landscape
p. 3–4 Urban Forestry in Edmond
p. 5–8
Urban Tree Canopy
p. 9–16 Urban Tree Canopy Assessment
17 –25 Discussion
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p. 26 Conclusion
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27 Literature Cited
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Edmond’s Landscape t he ci t y of edmon d
is located on the edge of the Cross Timbers forest,
described by the Ancient Cross Timbers Consortium, “the post oak and blackjack oak woodlands that form the western frontier of deciduous forest in Texas, Oklahoma and Kansas. The Cross Timbers are drought-stressed woodlands, populated by low stature, slow growing trees, some of which have potential of predating not only Oklahoma statehood, but also the birth of the United States.” The areas in Edmond where some of this forest still remains are undergoing increased pressure from development.
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Urban Forestry In Edmond Historically, Edmond has placed increasingly great value in its urban forest resource and its native landscape. The Edmond Urban Forestry Commission was created by ordinance in September 1999. Edmond became a Tree City USA in 2000 and has continued to maintain this designation over the years, in addition to attaining multiple Growth Awards. Emphasis on preserving the native landscape began in the early stages of the Edmond Urban Forestry Commission’s development. In 2001, the Edmond City Council adopted the Edmond Community Forestry Plan. Through approval of this plan, the City showed its dedication to raising community awareness of the importance and value of Edmond’s urban forestry assets. Under Goal 1, “Develop a Tree Management Program for Public Activities”, Objective G, “Preserve Native Forest Habitat”, the forestry plan states that “creating incentives and providing education to encourage greater preservation of native forest as part of the development process” is something to aspire to. The plan reemphasizes this by stating it repeatedly, along with requests to develop ordinances to reduce the impact of development on tree cover and topography. In 2003 and 2004, the City of Edmond took steps to delve deeper into the Cross Timbers preservation topic by conducting a two-part study, funded by Urban and Community Forestry Assistance Grants. This study was the first of its kind in Oklahoma, an effort to gain a better understanding about the Cross Timbers and other sensitive areas around Edmond. The consultant identified potential biologically sensitive areas throughout Edmond. Using historic data from the United States Department of the Interior such as tree cover from 1871, 1930 and 2001, the consultant found several locations determined as potentially
Historically, Edmond has placed increasingly great value in its urban forest resource and its native landscape.
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Integration of the natural area and remnant forest preservation concepts into Edmond Plan IV shows Edmond’s commitment to protection of the environment and the historic forest landscape.
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containing sensitive ecosystems or characteristics. Of special note were sites identified that may include pre-settlement remnant forests, or areas with trees that were present when Oklahoma became a state. Other areas included those that are considered biologically sensitive from a soil, archaeological or wildlife standpoint. The greatest amount of these sensitive areas exists in the eastern portion of Edmond. Those located in the western part of the City are smaller and less widespread due to pressures from urban expansion over the years. In 2007, Edmond City Council passed revisions to Title 22 in the Code of Ordinances, which addresses zoning. These revisions accounted for point values that are offered to developers for preserving trees as a part of the landscape point requirements in the site plan review process. The point values for tree preservation areas are favorable against those for clearing and installing new landscaping, and through this addition the City took a new step in the direction of preserving Edmond’s native landscape. Supporting this ordinance change is Edmond Plan IV which describes the basis of Edmond’s goals for preservation of natural areas and justification for this vision. Edmond Plan IV acts as a general guide for how the City should grow and develop over the long term. Integration of the natural area and remnant forest preservation concepts into Edmond Plan IV shows Edmond’s commitment to protection of the environment and the historic forest landscape. After mapping Edmond’s potential remnant Cross Timbers areas through the Sensitive Areas Project and incorporating their preservation into Edmond’s comprehensive planning process, the next step was the inventory of specific sites to determine whether they are in fact Cross Timbers, if they have pre-settlement trees. A study was conducted in the spring of 2010, which involved a small scale Cross Timbers inventory. Through the collection of trunk diameter and tree age measurements, the researchers analyzed the correlation between tree size, tree age and micro site characteristics of post oak trees on two adjacent sites. Post oak is considered to be an indicator of potential remnant forest because its life span and resiliency are greater than that of other Cross Timbers species. While no pre-settlement trees were found, there were multiple trees over 100 years old. Analysis of the study findings led to the conclusion that while presettlement trees may exist in Edmond, the measures taken to discover them are neither efficient nor necessarily useful. However, the findings from studying this small percentage of the “potential remnant forest” did re veal that these areas were very likely present at the time Oklahoma be came a state. In addition, these forested areas have great value beyond their historic worth and should be preserved to continue their legacy as established, thriving ecosystems. In short, the City of Edmond has shifted its focus from individual “witness trees” to the broader scale of entire stands of Cross Timbers forest and even more broadly, Edmond’s urban tree canopy.
Urban Tree Canopy W h at is a n U r ba n T r ee Ca nop y ?
Through the Sensitive Areas study, Edmond was able to identify where its forested areas are located. Through the spring 2010 study and site visits, it was confirmed that many of these identified areas are Cross Timbers forest. The social and political climate of Edmond supports the preservation of this historic landscape, which is a trademark to Edmond’s atmosphere and way of life. However, in order to approach recommendations for tree preservation and planting, the City needed to assess Edmond’s urban tree canopy (UTC) cover. UTC is a measure which, when viewed from above, refers to the amount of leaves, limbs and stems that shelter the ground (Grove & O’Neil-Dunne, 2011). It is expressed as a percentage of ground area that is covered by tree crowns. For example, a densely forested area with trees that have interlacing branches and no space between them may have a UTC of close to 100%. On the other hand, a prairie area with mostly grasses and very few trees may have a UTC of less than 5% (Lackner & Poracsky, 2004). Edmond’s environment falls in between, with a characteristic Cross Timbers forest comprised of both forested stands and open meadow in the midst of the built environment. UTC relates to the branching spread of the trees in an urban forest. Some UTC covers natural areas, while other UTC spreads across impervious surfaces such as roads and parking lots. Tree preservation, tree planting and improving tree health through proper tree care practices can contribute to a sustained or enhanced UTC. It is important
UTC is a measure which, when viewed from above, refers to the amount of leaves, limbs and stems that shelter the ground (Grove & O’NeilDunne, 2011).
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to note that tree species planted will influence the speed of UTC increase, due to varied growth rates and life spans. Proper tree maintenance, selecting the right tree for the right place and other proper techniques utilized by the Urban Forestry Department can help ensure that trees in Edmond grow to be as large and healthy as possible, contributing to a greater amount of UTC.
W h y is a n U r ba n T r ee Ca nop y I mporta n t ?
Urban and community forestry programs and communities can utilize UTC assessment to achieve maximized tree benefits provided by their urban forest.
A greater amount of UTC is sought by communities, because larger, mature trees provide greater amounts of tree benefits (see Table 1). In addition to the environmental services, greater UTC can contribute to more community pride and a greater sense of well being for constituents. UTC serves as storm water management infrastructure by catching rainfall that would otherwise end up in local streams and other bodies of water after running off paved surfaces and picking up debris and pollutants. Additional benefits of UTC include shade which reduces the urban heat island effect, energy conservation, cooler air temperatures, air purification, greater property values, wildlife habitat, community beautification, and improved quality of life (Center, 2008). What are the benefits of Urban Tree Canopy in a community?
• UTC reduces energy costs for cooling and heating buildings • Presence of healthy trees increases property values nearby • UTC beautifies the community • UTC catches rainfall that would otherwise run off and carry pollutants into waterways • Trees filter pollutants from the air • It provides shade and cools the surrounding area, reducing urban heat island effect • Wildlife utilizes UTC for food and shelter • UTC in urban areas improves quality of life by creating community pride and a greater sense of wellbeing Table 1. | Benefits of Urban Tree Canopy in a Community
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Urban and community forestry programs and communities can utilize UTC assessment to achieve maximized tree benefits provided by their urban forest. Not only can the assessment identify how much land area is currently covered by trees, but it can also help these programs and communities determine where there are new opportunities to plant trees and also how much impervious cover is present in the community and where it is located (National, 2009). “The goal of the UTC assessment is to provide decision makers with detailed metrics regarding the tree canopy that exists in the urban forest. The metrics allow them to not only understand the urban forest in its current state, but to plan feasible approaches to increasing UTC” (US Forest Service, 2012). By assessing UTC by land use, Edmond can identify its opportunities in management of the urban forest and use those results to recommend preservation or tree planting measures within the different land uses. Edmond may also make comparisons between UTC of undeveloped areas and UTC of developed areas. The differences in UTC in these areas may then be correlated to shifts in the community’s overall UTC that could occur if land development continues under the present standards. The City of Edmond can also utilize UTC measures to set target UTC goals for the city as a whole, in addition to various land use areas. The measures may guide planting prioritization, outreach program development, standards for site plan review and projecting future management needs for maintaining a thriving and healthy urban forest. See Table 2 for a summary of potential uses for study results.
By assessing UTC by land use, Edmond can identify its opportunities in management of the urban forest...
What Are Urban Tree Canopy Assessment Results Used For?
• • • • • •
Determining where there are opportunities to plant new trees By identifying concentrations of impervious cover, tree planting to reduce urban heat island effect may be prioritized Creating an understanding of the state of the urban forest and providing a resource for planning future management Identifying shortcomings in UTC in order to prioritize preservation and planting, thereby maximizing the UTC benefits experienced Projecting changes in future UTC by studying various land uses and contrasting with local development patterns Setting goals for desired UTC levels.
Table 2. | Uses of Urban Tree Canopy Assessment Results p.
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UTC assessment results in a picture of the urban forest that may be repeated in a set frequency to monitor the success of UTC goals. It is recommended to repeat UTC assessment every 5-8 years, since tree growth occurs slowly and would not show a measurable difference if assessed more often.
Edmon d U r ba n T r ee Ca nop y Gr a n t Proj ec t
One of the goals for this grant project includes “identifying tree canopy cover percentages of the overall Edmond community as well as the different land use areas.”
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In 2010, the City of Edmond received an Urban and Community Forestry Assistance Cost-Share Grant from the Oklahoma Department of Agriculture, Food and Forestry. One of the goals for this grant project includes “identifying tree canopy cover percentages of the overall Edmond community as well as the different land use areas.” By determining Edmond’s UTC, the City can also begin to address other goals of the grant such as developing a new site analysis process to determine the value of a given site’s existing landscape. The assessment also contributes to justification of forest preservation and setting and progressing toward a target UTC percentage. This last initiative contributes to Goal 1 (Develop a tree management program for public activities), Objective A (Establish and maintain optimum tree cover) of the Edmond Community Forestry Plan, which directs the Urban Forestry program to “determine a target percent tree canopy coverage”. The City of Edmond Urban Forestry program made use of the new i-Tree Canopy software for this UTC assessment. This software was developed by David J. Nowak, Jeffrey T. Walton and Eric J. Greenfield of the USDA Forest Service and modified for use on the i-Tree web site by David Ellingsworth, Mike Binkley, and Scott Maco of the Davey Tree Expert Company.
Urban Tree Canopy Assessment Met hods
i-Tree Canopy is “designed to allow users to easily and accurately estimate tree and other classes (e.g. grass, building, roads, etc.) within their city or any area they like. This tool randomly lays points (number determined by the user) onto Google Earth imagery and the user then classifies what cover class each point falls upon. The user can define any cover classes that they like and the program will show estimation results throughout the interpretation process. Point data and results can be exported for use in other programs if desired” (Binkley et al., 2011) To begin the assessment, the i-Tree Canopy web site at www.itreetools. org/canopy/index.php was first accessed (Image 9). From here, the first step in utilizing the software is to upload an ESRI shapefile which delineates the boundary of the area to be measured. The City of Edmond utilized a City Limits boundary shapefile initially, and then also measured individual shapefiles for boundaries of land use areas throughout Edmond City Limits. These land use areas included: Residential, Commercial, Industrial, Institutional, Transportation, Open Space, and Undeveloped. Table 3 shows descriptions of each land use area assessed. See Images 1-8 for aerial viewpoints of the different land uses.
i-Tree Canopy is “designed to allow users to easily and accurately estimate tree and other classes (e.g. grass, building, roads, etc.) within their city”
Continued on p. 14
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Land Use Areas
| a er i a l view poi n t
Westminister
Anderson
Hiwassee
Henney
Choctaw
Westminister
Anderson
Hiwassee
Henney
Choctaw
Post
Douglas
Midwest
Air Depot
Sooner
Coltrane
Bryant
Boulevard
Kelly
Santa Fe
Western
Pennsylvania Waterloo Sorghum Mill
Coffee Creek Covell Danforth Edmond
15th
33rd Memorial
Image 1. r esiden ti a l l a nd use a r e a s Single family residential housing
Post
Douglas
Midwest
Air Depot
Sooner
Coltrane
Bryant
Boulevard
Kelly
Santa Fe
Western
Pennsylvania Waterloo Sorghum Mill
Coffee Creek Covell Danforth Edmond
15th
33rd Memorial
Image 2. commerci a l l a nd use a r e a s Commercial and multi-family residential housing
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Westminister
Anderson
Hiwassee
Henney
Choctaw
Westminister
Anderson
Hiwassee
Henney
Choctaw
Post
Douglas
Midwest
Air Depot
Sooner
Coltrane
Bryant
Boulevard
Kelly
Santa Fe
Western
Pennsylvania Waterloo Sorghum Mill
Coffee Creek Covell Danforth Edmond
15th
33rd Memorial
Image 3. industr i a l l a nd use a r e a s Industrial zoning
Post
Douglas
Midwest
Air Depot
Sooner
Coltrane
Bryant
Boulevard
Kelly
Santa Fe
Western
Pennsylvania Waterloo Sorghum Mill
Coffee Creek Covell Danforth Edmond
15th
33rd Memorial
Image 4. institu tiona l l a nd use a r e a s Public schools, universities and non-park City owned land
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Land Use Areas
| a er i a l view poi n t
Anderson
Hiwassee
Henney
Choctaw
Anderson
Hiwassee
Henney
Choctaw
Westminister
Post
Douglas
Midwest
Air Depot
Sooner
Coltrane
Bryant
Boulevard
Kelly
Santa Fe
Western
Pennsylvania Waterloo Sorghum Mill
Coffee Creek Covell Danforth Edmond
15th
33rd Memorial
Image 5. tr a nsportation l a nd use a r e a s Street right-of-way, I-35 corridor and rail road land
Sorghum Mill
Coffee Creek Covell Danforth Edmond
15th
33rd Memorial
Image 6. open space l a nd use a r e a s Park land, golf courses and Arcadia Lake
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Westminister
Post
Douglas
Midwest
Air Depot
Sooner
Coltrane
Bryant
Boulevard
Kelly
Santa Fe
Western
Pennsylvania Waterloo
Anderson
Hiwassee
Henney
Westminister
Anderson
Hiwassee
Henney
Choctaw
Westminister
Post
Douglas
Midwest
Air Depot
Sooner
Coltrane
Bryant
Boulevard
Kelly
Santa Fe
Western
Pennsylvania Waterloo Sorghum Mill
Coffee Creek Covell Danforth Edmond
15th
33rd Memorial
Image 7. u ndev eloped l a nd use a r e a s Undeveloped lots and agricultural land
Choctaw
Post
Douglas
Midwest
Air Depot
Sooner
Coltrane
Bryant
Boulevard
Kelly
Santa Fe
Western
Pennsylvania Waterloo Sorghum Mill
Coffee Creek Covell Danforth Edmond
15th
33rd Memorial
Image 8. compr ehensi v e v iew of l a nd use a r e a s All land use areas previously mentioned in assessment
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After uploading an ESRI shapefile, cover classes were identified. For the measurement of all shapefiles used in the City of Edmond study, the cover classes collected included: Tree/Large Shrub, NonTree Vegetation, Soil/Bare Ground, Water, Impervious Building, Impervious Road/Street, and Impervious Other. See Table 3 for descriptions of each cover class.
The Residential land use area has the highest UTC, with 46.2%, followed closely by Undeveloped with 46.1%.
Cover Class Name
Description
Tree/Large Shrub
Vegetation classified as a tree or a large shrub
Non-Tree Vegetation
Any vegetation not classified as a tree or large shrub
Soil/Bare Ground
Ground surface with soil or mineral material exposed
Water
Bodies of water, not including swimming pools
Impervious Building
Any surface of a building including roofs or walls
Impervious Road/Street
Any roadways, excluding driveways or parking lot lanes
Impervious Other
Any other impervious surface such as parking lots, driveways, sidewalks, patios, swimming pools, etc
Table 3. | Cover classes used in determining Edmond’s land cover
After uploading the ESRI shapefile and identifying cover classes, classification of random points began (Image 10). I-Tree Canopy software selects random points throughout the boundary area, and the surveyor selects a cover class from a drop down menu which describes the type of cover present under the point marker. A minimum collection of five hundred points is recommended by i-Tree developers to prevent inaccuracy of analysis by a high standard of error. More points collected result in a lower standard of error, and thereby a more accurate assessment. For the purpose of the City of Edmond UTC assessment, one thousand points were collected for each shapefile surveyed. r e su lts
The UTC percentages for Edmond city limits and for Edmond’s different land uses may be found in Table 4, on page 16. The overall UTC coverage of Edmond city limits is 35.9%. The Residential land use area has the highest UTC, with 46.2%, followed closely by Undeveloped with 46.1%. Open Space has a UTC of 37.4%, Institutional land use has 23.8%, and Commercial has a UTC of 17.7%. The two lowest UTC measurements came from the Transportation land use with 15.4% tree cover and Industrial with 10.2%. For a visual depiction of cover class ratios within each individual land use, view Charts 2-9.
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Image 9. | i-Tree Canopy home screen
Image 10. | i-Tree Canopy point collection screen
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Cover Classes
Tree
Non-Tree Vegetation
Water
Soil/Bare Ground
Impervious Building
Impervious Road
Impervious Other
Edmond City Limits
35.9
42.9
4.1
3.0
5.5
4.0
4.5
Residential
46.2
30.8
0.4
1.3
10.8
5.7
4.8
Commercial
17.7
22.7
0.2
2.9
19.7
3.6
33.2
Industrial
10.2
29.9
0.8
21.3
10.4
2.0
25.4
Institutional
23.8
38.7
1.1
5.2
9.4
2.7
19.0
Transportation
15.4
41.6
0.1
1.9
0.0
36.2
4.7
Open Space
37.4
35.0
23.5
2.2
0.0
0.8
1.1
Undeveloped
46.1
49.2
1.6
2.3
0.1
0.1
0.6
Table 4. | Canopy Cover Class Percentages of Areas Assessed in the Edmond UTC Study.
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Discussion edmon d ci t y l i mi ts
The foliage of trees covers 35.9% of Edmond’s land, or roughly 20,096 total acres. These trees encompass the “urban forest” and include trees around homes, along roads, in parks, in the floodplain, around businesses and institutions and on undeveloped or agricultural lands. A large amount of grass, shrubs, roads and buildings exist beneath the branches and foliage that make up tree canopy. While nontree vegetation actually covers an even larger area than depicted in the study, much of this vegetation is covered up by tree foliage and is therefore classified as UTC. Similarly, much of the land area encompassed with buildings, roads or other paved surfaces may fall under the Tree cover class because trees grow across and protect these surfaces. Continued on p. 20
The foliage of trees covers 35.9% of Edmond’s land, or roughly 20,096 total acres.
Land Use
Acreage
Land Percentage
Undeveloped
24582.93
43.92
Residential
18075.23
32.29
Open Space
6786.54
12.12
Table 5. | Acreage and per-
Institutional
1351.98
2.42
encompassed by each land use
Commercial
2314
4.13
Transportation
2206.53
3.94
Industrial
661.44
1.18
centage of Edmond city limits
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Ratio of Coverage Classes
| l a n d use a r e a s
Ratio of Coverage Classes
| l a n d use a r e a s
Edmon d ci t y l i mi ts
Chart 2. | Ratio of Cover Classes
4.5 % 4.0 % 5.5 % 3.0 % 4.1 %
Impervious Other Impervious Road/Street Impervious Building Soil/Bare Ground Water
4 2.9 % Non-Tree Vegetation
35.9 % Tree
r e side n t i a l
Chart 3. | Ratio of Cover Classes
4.8 % Impervious Other 5 .7 % Impervious Road/Street 10.8 % Impervious Building 1.3% Soil/Bare Ground 0.4 % Water 30.8% Non-Tree Vegetation
4 6.2% Tree
commerci a l
Chart 4. | Ratio of Cover Classes
33.2% Impervious Other 3.6% Impervious Road/Street 19.7 % Impervious Building 2.9 % Soil/Bare Ground 0.2% Water 22.7 % Non-Tree Vegetation
17.7 % Tree
i n dust r i a l
Chart 5. | Ratio of Cover Classes
25.4% Impervious Other 2.0% Impervious Road/Street 10.4% Impervious Building
21.3% Soil/Bare Ground 0.8% Water 29.9% Non-Tree Vegetation
10.2% Tree
i nst i t u t iona l
Chart 6. | Ratio of Cover Classes
19.0% Impervious Other 2.7 % Impervious Road/Street 9.4% Impervious Building 5.2% Soil/Bare Ground 1.1% Water
38.7% Non-Tree Vegetation
23.8% Tree
t r a nsportat ion
Chart 7. | Ratio of Cover Classes
4.7% Impervious Other
3 6.2% Impervious Road/Street 0.0% Impervious Building 1.9% Water 0.1% Soil/Bare Ground
41.6% Non-Tree Vegetation
15.4% Tree
ope n space
Chart 8. | Ratio of Cover Classes
1.1% 0.8% 0.0% 2.2 %
Impervious Other Impervious Road/Street Impervious Building Soil/Bare Ground
23.5% Water
35.0 % Non-Tree Vegetation
37.4% Tree
u n de v el oped
Chart 9. | Ratio of Cover Classes
0.6% 0.1% 0.1% 2.3% 1.6%
Impervious Other Impervious Road/Street Impervious Building Soil/Bare Ground Water
49.2% Non-Tree Vegetation
46.1% Tree
r e side n t i a l
The unknown concern that may warrant further study is whether new developments are built in the same style as what resulted in the very favorable current canopy percentage.
Edmond’s land uses vary drastically in the amount of land area covered by tree canopy in each type. Tree canopy covers 46.2% of Edmond’s Residential areas, making up the largest ratio of UTC to other cover types. Residential areas are also the second largest land use in Edmond, making up 18075.23 acres and 32.29% of Edmond city limits. Due to the Residential land use’s large area ratio on Edmond land, the high UTC number in Residential areas greatly impacts the favorable UTC percentage for Edmond overall. Many residential developments in Edmond have built homes into the forest stands rather than completely clearing the forest to lay out residential lots. In addition, many Edmond residents see the value in planting trees around their properties for shade, screening, energy savings and aesthetics. Residents are showing that trees are important to them. The City continues to accommodate and support this value by providing programs such as tree distributions at Arbor Day, the Edmond Electric Open House, Apache Foundation distributions, and the Foster-A-Tree program. Continuing the support for such programs furthers the enhancement of UTC in Edmond’s Residential land use areas and maintains tree cover after losses from storm events, inclement weather conditions, pests and disease and other issues. Residents will likely continue to plant trees by their own accord as a result of active educational programs about the benefits and value of trees in the community. Edmond is also fortunate to attract a citizenry that value trees and reside in this community partly because of the beauty of the forested Edmond landscape. The unknown concern that may warrant further study is whether new developments are built in the same style as what resulted in the very favorable current canopy percentage. Do they exhibit the same sensitivity and flexibility toward existing trees? It is difficult to predict how new residential developments will affect the Residential land use UTC. There are currently no tree planting or preservation standards required of new single family residential developments.
U n de v el oped
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Undeveloped land includes the second largest ratio of UTC cover, at 46.1%. Comprised of both undeveloped lots and agricultural property, most of Edmond’s remnant Cross Timbers forest is found within the Undeveloped land use. These areas have seen little disturbance, support thriving forest and prairie ecosystems full of wildlife and native plants and trees, and provide a multitude of environmental services. In addition to these benefits the historic landscapes hold important cultural value. It is important to note that a change in zoning of currently undeveloped lots may adversely impact the City’s UTC levels in a significant way. The Undeveloped land use currently makes up 24,582.93 acres, or 43.92% of Edmond’s total land area, which is the largest land use area in Edmond. See Table 5 for a comparison of acreages between the different land uses utilized in this study. Depending on the change in land use, an undeveloped lot could see a reduction in UTC of as much
as 36.4%. In addition, large areas of potential remnant forest could be wiped out as a result of site design that does not involve planning around existing trees up front. Changing the current landscape standards to include a greater emphasis on tree preservation and placing a focus on the benefits of retaining older, established, larger sized trees rather than clearing forest and then planting greater numbers of young trees can help to reverse this effect. It’s important to note that the undeveloped areas currently encompass much of Edmond’s existing Cross Timbers and potential remnant forest. Given the environmental and cultural significance of this important ecosystem, a carefully balanced approach to development is necessary in these areas. Ope n Space
The Open Space land use includes park land and golf courses, and like the Undeveloped land use it also includes much of the area identified as potential remnant forest. Open Space is the third largest land use area, encompassing 12.12% of Edmond with 6786.54 acres. The City has retained the natural landscape in many park land areas, which influences the Open Space land use standing as the third highest ratio of UTC, at 37.4 %. Arcadia Lake falls into this land use, and the federally owned natural areas along the perimeter of the lake greatly influence the UTC level within Open Space in Edmond as well. The Parks and Recreation Department actively plants trees throughout Edmond parks to provide shade for park patrons and to frame activity areas. Through these efforts, UTC in park land will likely stay relatively the same or could potentially increase.
Depending on the change in land use, an undeveloped lot could see a reduction in UTC of as much as 36.4%.
i nst i t u t iona l
In the areas including public school grounds, University of Central Oklahoma’s campus, and non-park City owned property, 23.8% of the ground surface spans beneath tree canopy, in the fourth highest UTC land use area. The Institutional land use incorporates any school, university, or City property that is not a park, and these areas add up to 1351.98 acres, or 2.42% of Edmond city limits. One large City-owned property contributing to the UTC percentage is the Cross Timbers Complex, which houses Public Works Administration and Edmond Electric. When it was built in 2006, the City met landscaping requirements by preserving 24 acres of native Cross Timbers forest on the 137 acre lot, in addition to planting new trees around parking areas and along the entrance road. Many other buildings owned by the City of Edmond are surrounded by trees in the streetscape, but not all City properties have been assessed for opportunity to plant new trees. University of Central Oklahoma maintains a heavily planted landscape throughout campus, providing shade for students and contributing to the beauty of the institution. Programs such as Shade Trees on Playgrounds, established by the Tree Bank, may contribute to installation of new trees on school properties and an increase in tree canopy Continued on p. 24
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Visual Comparison
| t r e e c ov e r age
Visual Comparison
| t r e e c ov e r age
35.9% t r e e c ov e r age
Edmond City Limits
23.8% t r e e c ov e r age
Institutional
46.2% t r e e c ov e r age
Residential
17.7% t r e e c ov e r age
Commercial
46.1% t r e e c ov e r age
Undeveloped
15.4% t r e e c ov e r age
Transportation
37.4% t r e e c ov e r age
Open Space
10.2% t r e e c ov e r age
Industrial
cover. Possible partnership opportunities may be available for putting forth an effort to assist with foresting school grounds and providing relief for students from the heat and skin damage resulting from direct sunlight.
Com merci a l
Possible partnership opportunities may be available for putting forth an effort to assist with foresting school grounds ...
Consisting of non-industrial businesses, multiple family housing, and private schools, the Commercial land use is currently only 17.7% covered by UTC. Commercial properties are subject to requirements related to a certain quantity of plants that must be installed on a site relative to the lot size. While preservation of existing trees is encouraged and incentivized through higher point values in the Title 22 Zoning ordinance, no requirements currently exist for retaining existing trees on a site. Even in the instance of a developed site with landscaping that has matured, a new business moving onto that site will often remove and replace landscaping as part of their site modifications. The outcome is a business with relatively mature trees that could have provided shade, energy conservation and other environmental and economic benefits that are instead replaced with young trees. These young trees will take several years to reach the production level of the previous trees, while years of services are lost. Even with improved tree preservation measures the Commercial land use goal for UTC will realistically be lower since the area of paved surfaces and buildings per lot is greater than in other land uses. However, it is important to note that incorporating numerous trees throughout these areas can reduce the frequency of paved area resurfacing, the amount of storm water runoff and drainage problems, and can attract customers and improve aesthetics. Commercial properties currently make up 2314 acres, or 4.13% of Edmond’s land area. Given the difference in UTC between Commercial lots and Undeveloped lots and the vast amount of Undeveloped land that is likely to change land use in the future, Edmond’s UTC could be negatively impacted by zoning changes if landscaping practices continue in the same fashion.
T r a nsportat ion
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Transportation areas include public right-of-way throughout Edmond, as well as Interstate Highway 35 (I-35) right-of-way and railroad property. These areas make up 2206.53 acres, or 3.94% of Edmond. Relatively few trees grow along I-35, as Oklahoma Department of Transportation (ODOT) maintains the right-of-way with a large clear zone on either side. However, some of the exit ramps have natural stands of trees and others are planted with trees funded by ODOT grants. Railroad property is also relatively clear of trees, which contributes to the low UTC of 15.4% in the Transportation land use. The large portion of City right-of-way encompassed by paved roads also contributes to this number, but many of these roads are shaded by tree canopy as well. As roads are reconstructed, a landscape plan normally
accompanies the street plans. Many streets in Edmond have trees installed in the center median as a result of this practice. In other areas, the City has planted trees in the median or along the side rightof-way through ODOT grants or other Urban Forestry programs. Trees installed through the Foster-A-Tree program also contribute to UTC in the right-of-way. As additional Foster trees and right-of-way plantings are added and current Foster trees and civic plantings mature, the Transportation land use UTC level may continue to rise. However, with the redevelopment of arterial roads in Edmond, some UTC within the Transportation land use may also be lost.
I n dust r i a l
Industrial areas, 1.18% of Edmond (661.44 acres), make up the land use that is least covered by tree canopy, with a UTC level of 10.2%. These areas often stage large equipment and supplies, which leaves little room for trees to grow without conflicting with uses of the site. As new industrial sites develop, the City can encourage the preservation of existing trees in areas of the site that are less likely to be used for staging or transportation, to increase the tree benefits experienced on that site. There may also be opportunity for additional tree planting within the parking lots of industrial sites.
Given the difference in UTC between Commercial lots and Undeveloped lots and the vast amount of Undeveloped land that is likely to change land use in the future, Edmond’s UTC could be negatively impacted by zoning changes if landscaping practices continue in the same fashion.
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Conclusion
Edmond has come to the verge of a pivotal shift on how landscaping on development sites is viewed. Rather than being valued solely for beautification, trees throughout the city are valued as environmental management infrastructure.
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The City of Edmond is fortunate to have natural resources of all kinds, and the urban forest is one that may be managed and used wisely for the benefit of future generations. Currently, the UTC of Edmond city limits remains at a healthy range. However, as undeveloped lands (which make up nearly half of Edmond’s land area) are cleared and built upon this could change drastically. Edmond has come to the verge of a pivotal shift on how landscaping on development sites is viewed. Rather than being valued solely for beautification , trees throughout the city are valued as environmental management infrastructure. By retaining healthy, mature trees and planting new trees, the future of tree benefits in Edmond may be ensured for generations to come. Initially, the City should use these UTC findings to set goals for urban tree cover throughout city limits and also in each land use area. In order to track changes in UTC, the Urban Forestry Department should conduct a canopy assessment once every five years. Positive changes to UTC on development sites depend on a change in site assessment standards and methods for calculating landscaping requirements. Without these changes, the current trends in landscaping practices will continue and new sites converted from undeveloped to other land uses will see a larger reduction in UTC. The results of this study are also valuable for developing tree planting partnerships and outreach programs to encourage tree planting and preservation throughout the City. Through public education efforts, urban forest management planning, and policy changes, the City of Edmond can enhance UTC and improve any practices that currently adversely affect UTC levels. As water and energy become increasingly critical resources, the environmental services provided by community trees will continue to elevate in importance. Developing active management standards for UTC in Edmond now can result in greater relief realized from UTC infrastructure in the future, when it becomes most vital. The City of Edmond has the potential to maintain, enhance, and preserve its local ecosystems and Cross Timbers forest by thoughtfully planning for and appropriately developing the community.
Literature Cited Binkley, M., Ellingsworth, D., Greenfield, E. J., Maco, S., Nowak, D. J., & Walton, J. T. (2011). i-Tree Canopy Technical Notes. Retrieved January 11, 2012, from i-Tree: http://www.itreetools. org/canopy/resources/iTree_Canopy_Methodology.pdf Center for Watershed Protection; US Forest Service. (2008). Urban Tree Canopy. Retrieved January 11, 2012, from Watershed Forestry Resource Guide: http://www.forestsforwatersheds. org/urban-tree-canopy Grove, J. M., & O’Neil-Dunne, J. (2011, August 1). Urban Tree Canopy Analysis Helps Urban Planners With Tree Planting Campaigns. Retrieved January 11, 2012, from Alliance for Community Trees: http://actrees.org/news/trees-in-the-news/research/ urban_tree_canopy_analysis_helps_urban_planne/ Lackner, M., & Poracsky, J. (2004). Urban Forest Canopy Cover in Portland, Oregon, 1972-2002: Final Report. Portland: Portland State University Cartographic Center. National Association of State Foresters; Urban and Community Forestry Committee. (2009). Assessing Urban Forest Canopy Cover: A Primer for State Foresters. Washington, D.C.: National Association of State Foresters. University of Arkansas Tree-Ring Laboratory. (2012) the Ancient Cross Timbers Consortium. http://www.uark.edu/misc/xtimber/index.html US Forest Service, Northern Research Station. (2012). Urban Tree Canopy. Retrieved January 11, 2012, from Urban Natural Resources Stewardship: http://nrs.fs.fed.us/urban/utc/
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no t e s
Edmond Urban Tree Canopy Report U r ba n for e st ry depa rt me n t, 2012
The Edmond Urban Tree Canopy Study was conducted through an Urban and Community Assistance Grant received in 2010 through the Oklahoma Department of Agriculture, Food and Forestry and the USDA Forest Service. The USDA is an equal opportunity provider and employer.
edmondok.com/trees
Produced by the City of Edmond’s Marketing and Public Relations Department Š 2012 UF1012