GREENBELT URBAN FOREST MASTER PLAN

Greenbelt’s trees are iconic features of this historic community, creating an urban oasis that provides a high quality of life to residents. Our vision is to develop a tree master plan for streets and other public areas in the City of Greenbelt. This plan will provide for the care, preservation, pruning, planting, and replanting of trees. The tree master plan will also foster the sustainability of Greenbelt’s urban forest. Our goal is to maintain and expand upon this legacy, both today and for future generations. – Greenbelt Vision Statement

November 2018

Prepared for: City of Greenbelt 555 Crescent Road Greenbelt, Maryland 20770 Prepared by: Davey Resource Group, Inc. 1500 North Mantua Street Kent, Ohio 44240 800-828-8312

TABLE OF CONTENTS Introduction ...... 1 Figures State of Greenbelt’s Urban Forest ...... 5 1. Location of Greenbelt in relation to the District Threats to The Future Urban Forest ...... 12 of Columbia ...... 2 Vision for Greenbelt’s Urban Forest...... 16 2. Greenbelt land cover map ...... 6 Next Steps ...... 16 3. Location of inventoried street trees ...... 7 Funding ...... 41 4&5. Species and genus distribution of Greenbelt's Going Forward: Five-Year Plan ...... 44 street trees ...... 9 Conclusion ...... 47 Glossary ...... 48 6. Age distribution of Greenbelt's public trees ...... 10 References ...... 51 7. Relationship between average tree condition class and number of years since last pruning ...... 17 Tables 8. One green street concept from Cherrywood Lane Study ...... 33 1. Benefits Provided by Greenbelt's Tree Canopy ...... 3 2. Tree Canopy Analysis 2007 ...... 5 Appendices 3. City Canopy Comparisons ...... 6 4. Tree Canopy Cover by Land Use; Source University A. Tree Risk Assessment Terminology of Vermont ...... 7 B. Tree Risk Zone Categories for Public Trees 5. Condition of Greenbelt's Street Trees ...... 8 C. Examples of Tree Risk Management Goals 6. Budget Estimates and Recommendations D. Tree Management Software Options for Greenbelt ...... 41 E. Tree Emergency Plan Worksheet F. Canopy Benefit Methodology

Davey Resource Group i November 2018 INTRODUCTION The City of Greenbelt, Maryland is well known in the region as an “urban oasis” and has an extensive tree canopy in many areas. The large tracts of mature trees and the street and park tree resources provide numerous benefits to residents, including contributions to stormwater management, public health, energy, and pollution management. Like many communities in densely populated urban areas, the environmental, economic, and social benefits and services provided by trees become more important each year as resident, worker, and visitor populations increase, and bring with them the desire for a high quality of life. Trees are an important component of an integrated municipal response to urban development. They can only provide maximum benefits if they are properly and proactively managed. After assessing the extent of tree canopy in a 2007 study, followed by a partial volunteer street tree inventory in 2013, assessing forest health in 2016 (Thomas 2016), Greenbelt has taken the next step in proactively planning for this city asset. Partnering with Davey Resource Group, Inc. “DRG”, the City of Greenbelt has developed an urban forestry master plan that incorporates all current studies performed with community input/goals and DRG’s urban forestry management expertise to create a roadmap for the long-term management and preservation of Greenbelt’s valuable tree canopy cover. Fortunately, the overall canopy level currently in Greenbelt is considered to have a high level of forest cover (over 60%), but this percentage is somewhat overstated due to the large forest preserves that surround the community. Several factors threaten the canopy that may compromise future coverage in Greenbelt. Close assessment of these factors is important. This report provides an overview of the findings, current conditions in Greenbelt, and a five-year plan for implementing the 11 recommendations detailed. Summary of Challenges in Greenbelt Summarized below are a number of challenges that emerged during the development of this plan. Each are discussed in more detail throughout the report and addressed in the 12 recommended Next Steps. Lack of Diversity (Species and Ages). Greenbelt’s public tree population exhibits a lack of biodiversity and diversity of sizes/ages, which can equate to higher maintenance and care needs thanks to higher susceptibilities to native and exotic pests/diseases and loss of mature trees during severe storm events. Lack of Data for Risk Management and Public Safety. Greenbelt is fortunate to have a substantial canopy and extensive trail network, although these assets come with a level of risk. Public trees must be regularly evaluated to prevent injury or damage. Greenbelt’s challenge to minimize risk to reasonable levels stems from a lack of complete inventory data for all public trees, and from insufficient staffing levels and/or availability to perform risk assessments and mitigation on a regular basis.

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Trees and Utility Conflicts. In recent years, many trees under utility lines have been severely pruned and even removed. Fortunately, Greenbelt has been working with PepCo (and other utilities) to collaborate and share the right-of-way (ROW) space to the benefit of the entire community. As this has been one of the more hotly debated issues from the public, a more intensive public outreach and education strategy around this topic is needed. Pests and Invasive Species. Diseases, pests, and invasive plants exist in Greenbelt’s urban forest and should be proactively controlled. While diversity is the first key to pest and disease management, other actions are needed to stay ahead of threats on the horizon. Limited Resources. Like many municipalities, achieving a proactive urban forest management program in Greenbelt is challenged by limited resources. Community goals for tree pruning, plant health care, routine inspections, reduced tree risks, leaf and brush collection, tree planting and new tree care, and wood waste disposal are high. Staffing, equipment, and funding dedicated to urban forestry, however, is limited. Future Development. Despite the fact that the majority of the available land in Greenbelt is fully developed, there are tracts of wooded land and mature tree canopy at risk. In addition, Greenbelt’s forest preserves are not protected in perpetuity. Without clear measures of proactive protection in place (urban tree canopy goals, a more robust ordinance, conservation easements, etc.), Greenbelt does run a risk of future canopy loss. About the Study Area The City of Greenbelt, Maryland, located northeast of Washington, D.C., is a leader in environmental stewardship (Figure 1). Founded in 1937 as one of America’s first planned communities and “Garden Towns,” the layout of the city was designed for sustainability and community interaction. From the beginning, the strong connection between the city and trees was obvious. Greenbelt took its name from the belt of green forestland that surrounded the city and the belts of green between neighborhoods that offered easy contact with nature. Over the years, Greenbelt’s citizens have remained active in local greening and preservation efforts. As a result, the city has retained much of its original charm and natural assets.

Figure 1. Location of Greenbelt in relation to the District of Columbia.

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Why Trees? In an age of tight municipal budgets, aging infrastructure, and fierce competition for city resources, why should valuable funds be spent on trees? The simple answer is that trees provide numerous and valuable social, economic, environmental, and aesthetic benefits to residents of Greenbelt. Trees strengthen neighborhoods, calm traffic, create better pedestrian and bicyclist experiences, and help bolster the retail base by enhancing the attractiveness of commercial areas. Trees also reduce stormwater runoff, thus reducing both pollution and the cost of stormwater management. In this way, they protect and conserve watersheds, streams, wetlands, and groundwater, which improves the water quality of the Chesapeake Bay. Because we have data on the tree canopy land cover Table 1. Benefits Provided by Greenbelt’s Tree Canopy (just over 60%) in Greenbelt, we are able to Environmental Benefits Provided by calculate the value of some of the benefits those Quantity Unit Benefit Value trees provide using the U.S. Forest Service’s i-Tree Greenbelt’s Tree Canopy AIR: Carbon Monoxide (CO) Removed 6,402 lbs. $4,268 suite of tools. Greenbelt’s canopy provides AIR: Nitrogen Dioxide (NO ) Removed 29,451 lbs. $6,358 benefits calculated at just under $1.3 million to 2 AIR: Ozone (O ) Removed 115,780 lbs. $139,113 the city annually. Table 1 presents a summary of 3 AIR: Sulfur Dioxide (SO ) Removed 13,368 lbs. $615 the type, quantity, and monetary value of these 2 AIR: Dust, Soot, Other Particles Removed services (detailed methodology found in 39,281 lbs. $524,327 (Particulate Matter, PM10 and PM2.5) Appendix F). STORMWATER: Reduction of Runoff 37,459,544 gals. $334,738 Greenbelt’s urban forest is one of its most defining CARBON: Sequestered 2,280 tons $288,028 characteristics of the city and is already considered Annual Benefits Value $1,297,449 CARBON: Storage Over Canopy’s Lifetime a priority within the community: 94,879 tons $11,984,730.11 (not an annual benefit) ● As acknowledged in the 2001 Greenbelt Total Benefits Value Overall $13,282,179 Metro Area Plan, trees are an important Source: i-Tree Landscape (see Appendix F for methodology) component of the city, but also of the region. ● The Sustainability Plan Framework for the City of Greenbelt contains these goals: protect existing forested lands; protect and increase the existing tree canopy; increase residential tree canopy; and adopt tree protection ordinances.

● The Public Works Strategic Plan states these goals: maintain and beautify Greenbelt’s green spaces, parks, and outdoor recreational areas; finalize a sustainable land care policy; and implement environmental improvements and sustainability practices throughout the city.

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In addition to the monetary benefits laid out in Table 1, there are a wealth of other benefits trees provided as shown below.

There is no question that trees provide effective solutions to many urban challenges in Greenbelt. Upon learning about the magnitude of these services, many communities often want to start planting more trees right away. However, to effectively and efficiently make long-lasting improvements, it is important to first accurately assess the state of the existing urban forest, establish goals for the future, and use this information to map out the most effective ways to move forward.

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STATE OF GREENBELT’S URBAN FOREST Before prescribing strategic and operational recommendations to reach the city’s vision About Canopy Cover of itself and goals for its urban forest, an understanding of Greenbelt’s existing conditions Canopy cover is a measure of the is essential. physical coverage of the tree canopy Greenbelt’s Tree Canopy over the land. It represents a way of expressing, as a percentage, how much Tree canopy cover is the total amount of land covered by trees when viewed from above. of any given area is shaded or protected Urban tree canopy (UTC) is the combination of both private and public trees within city by trees. Canopy cover is an important limits. way of measuring the character, Current Canopy is High. The most recent UTC analysis (completed in 2007) found that location, amount, and benefits of an 62% of Greenbelt is covered by tree canopy, while 33% of the city is covered by urban forest. impervious surfaces that repel stormwater (roads, buildings, etc.), as shown in Table 2 Broad calculations suggest that large and depicted in Figure 2. mature trees provide 75% more environmental benefits than smaller Table 2. Tree Canopy Analysis 2007 trees.

2007 (Vermont) As a single large tree covers more area Greenbelt Land Cover in 2007 than several small trees, the measure of Acres Percent canopy cover is more valuable than Impervious (roads, buildings) 1,346 33% simply counting the total number of

Tree Canopy 2,516 62% trees. It is a repeatable benchmark that Low Vegetation (grass, shrubs) 162 4% can be measured regularly to guide Bare Earth 0 0% future tree planting programs and land

Water 41 1% development, and help determine the Total 4,065 100% successes or failures of urban forest Source: University of Vermont Canopy Study 2007 management efforts.

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Table 3. City Canopy Comparisons City Canopy Comparisons Existing Canopy Canopy Goal % Year % By Greenbelt, MD 62% 2007 Increase - Atlanta, GA 48% 2008 Increase Ongoing Charlotte, NC 47% 2012 50% 2050 Mamaroneck, NY 46% 2016 Increase - Whitpain, PA 43% 2012 Increase Ongoing Annapolis, MD 42% 2006 50% 2036 Pittsburgh, PA 40% 2011 60% 2031 New Haven, CT 38% 2009 Add 10K Trees 2014 Washington, DC 35% 2009 40% 2029 Holyoke, MA 27% 2014 30% Ongoing Easton, MD 27% 2014 40% Ongoing Hartford, CT 25% 2013 35% Ongoing New York, NY 24% 2006 30% 2036 Greensboro, MD 23% 2015 -- -- Providence, RI 23% 2007 30% 2020 Asbury Park, NJ 23% 2013 Increase Ongoing Figure 2. Greenbelt land cover map. Baltimore, MD 20% 2007 40% 2036 Philadelphia, PA 20% 2011 30% 2025 Howard Beach, NY 8% 2013 Increase Ongoing

Canopy Compared to Other Cities. Greenbelt is significantly ahead of most communities in tree canopy, in large part due to the original green plan for the community (Table 3). There is no formal canopy goal set in Greenbelt, although Prince George’s County codifies minimum canopy per land use in its development regulations. The county code states that commercial land use types are required to have at least 10% tree canopy cover. Most dense residential or mixed use must have 15% canopy cover. Low-density residential land is required to have 20% canopy cover.

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Canopy is Not Equally Distributed. While overall tree canopy Table 4. Tree Canopy Cover by Land Use; is high, two land uses, "housing" and "culture and recreation", Source University of Vermont. have the most of the city's tree canopy cover at 26% and 18%, Existing UTC respectively (Table 4). If the forest preserves and Greenbelt Land Use National Park are removed from the city's overall tree canopy % Land % Category calculation, canopy coverage of the developed areas in Greenbelt Housing 26% 64% drops to about 43%. Additionally, over one-third of the city's Culture and Recreation 18% 97% total tree canopy is located on land designated for housing with ROW 8% 43% tree canopy covering 64% all housing lands. Future losses of greenspace and possible redevelopment of private housing where Vacant Land 8% 57% trees are removed to increase building footprints, or other Resource Production 1% 80% impervious or pervious surfaces, could dramatically reduce Government Services and Institutional 0% 24% Greenbelt's overall tree canopy coverage. Industrial Production 0% 24% Office Buildings and Selected Services 0% 28% Why is equitable distribution of tree canopy important? It ensures all residents, businesses, and workers experience and have equal Retail Trade 0% 17% access to the benefits trees provide – same air quality, water Transportation, Communication, and… 0% 52% quality, boost to property Warehousing and Wholesale 0% 17% values, and more.

Greenbelt’s Public Trees City-managed trees on public lands, along with current management practices, were also examined. Greenbelt has held a Tree City USA designation for the past 17 years, thanks to its Advisory Committee on Trees (ACT), a tree care ordinance, a community forestry program, and an Arbor Day celebration. Other findings from this examination lend insight into Greenbelt’s tree population. Only Half of Public Trees Inventoried. Greenbelt has currently inventoried approximately 2,700 trees. The city estimates that number to represent about half of the trees on public land. For the purposes of this plan and further analysis, the current inventory was projected to 5,000 trees holding the same distribution and ratios. The current inventory shows that over 50% of trees in Greenbelt are in the ‘East’ section of the city. The inventory was performed by groups of students from the University of Maryland over a week- Figure 3. Location of inventoried street trees. long period; the data collected included only tree location, size (measured by the diameter at breast

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height, or DBH), and species (Figure 3). This is a good start to assess the urban forest; however, complete data are required to fully understand the condition of and issues with the public tree resource. An inventory that uses GPS/GIS technologies to map all public trees and includes tree and site attributes, such as condition, risk rating, and maintenance needs (as determined and verified by a Certified Arborist), is critical for effective management and care, and for ensuring public safety. A complete inventory that follows industry standards is an area in need of improvement. Most Trees in Good Condition. Based on the existing and extrapolated inventory data as collected by volunteers, overall tree health (almost 80%) is reported to be in either “Great” or “Good” condition (Table 5). At the time of the inventory, only 3% of trees were either identified as “Dying,” needing attention, or were removed. Condition data were only available for some trees and should not be considered accurate enough for urban forest management or risk mitigation purposes, as they were collected by students and volunteers.

Table 5. Condition of Greenbelt’s Street Trees (from volunteer inventory) # of % of Estimated Estimated Estimated Estimated Condition West Central East Trees Trees West Central East Greenbelt Great 50 116 199 365 13.2% 91 210 361 662 Good 263 414 1,126 1,803 65.4% 477 751 2,043 3,271

Fair 64 110 134 308 11.2% 116 200 243 559 Poor 7 29 46 82 3.0% 13 53 83 149 Dying 1 3 7 11 0.4% 2 5 13 20 Attention Required 4 4 2 10 0.4% 7 7 4 18 Removed 16 24 24 64 2.3% 29 44 44 116 No Data 23 41 49 113 4.1% 42 74 89 205

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Low Diversity of Species. The biodiversity of Greenbelt’s urban forest is low. The composition of a tree population city-wide should follow the general “10-20-30 Rule” for diversity: a single species should represent no more than 10% of the urban forest, a single genus no more than 20%, and a single family no more than 30%. Based on inventoried trees in Greenbelt, there are both species and genera that exceed these recommended thresholds. As shown in Figures 4 and 5 below, red maple and Callery pear exceed the recommended 10% species threshold, with pin oak just approaching the limit. The Pyrus (pear) and Acer (maple) genera also exceed the recommended 20% thresholds. For these reasons, future plantings should scale back on the selection of these species and genera whenever possible to correct the biodiversity issues discussed here.

Species Distribution of Gensus Distribution of Greenbelt's Street Trees Greenbelt's Street Trees

Other, 24% Callery Pear, 28% Other, 27% Pyrus, 27%

littleleaf red maple, Lagerstroemia, 7% linden, 5% 15% London Acer, 22% planetree, pin oak, 5% 9% Quercus, 16% willow oak, 5% crape myrtle, 7%

Figures 4 and 5. Species and genus distribution of Greenbelt's street trees. Percentages were rounded by software and may not add up to 100%.

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Better Age Distribution Needed. Analyzing the age of the city-wide tree population (via tree size) offers insight into maintenance practices and needs, as well as a prediction on the longevity of the canopy as a whole. A tree population with an ideal distribution would have an abundance of newly planted and young trees, and lower numbers of established, maturing, and mature trees. The ideal distribution calls for the largest quantity of trees (approximately 40% of the total population) to be considered young (less than 8 inches diameter at breast height, or DBH), while a smaller fraction (approximately 10%) should be in the large-diameter size class (greater than 24 inches DBH) (Richards 1983). Figure 6 below shows the age distribution of public trees in Greenbelt, both in quantity and percentages. The actual distribution (blue line) is close to the recommended distribution (dotted line). In the end, a variety of age trees are needed, so Greenbelt should continue its focus on both constant care for older mature trees and annual planting of new trees.

Greenbelt Public Tree Age Distribution By Tree Type & Overall 1,600 60%

1,400 50% 50%

1,200

40% 40% 1,000 36% 30% 800 30%

600 Quantity of Treesof Quantity 20% 20%

400

12% PopulationTreeof Total% 10% 10% 200

1% 0 0% 0"-8" 9"-17" 18"-24" 25"+ Tree Age Shown in Diameter at Breast Height (DBH) Pears Oaks Maples All Other Species Actual % Distribution Ideal % Distribution

Figure 6. Age distribution of Greenbelt’s public trees.

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Players in Greenbelt’s Urban Forest There are a number of active groups in Greenbelt that impact, influence, and/or otherwise affect the urban forest at some level throughout the year. These stakeholder groups are important to identify, as they provide a starting point for outreach, education, collaboration, and potential project partners.

● City of Greenbelt: Public Works ● City of Greenbelt: Planning ● Advisory Committee on Trees ● Forest Preserve Advisory Board ● Commercial Property Owners ● Greenbelt Homes, Inc. (GHI), a housing cooperative of townhomes in Greenbelt ● Prince George’s County ● Federal Government ● Utilities: PepCo, Water, Sewer, etc.

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THREATS TO THE FUTURE URBAN FOREST Greenbelt’s tree canopy is substantial, and proactive action is needed to sustain it. As a living asset, trees and urban forests are vulnerable to damage, loss, and degradation. The risks from storms, insects and disease, climate change, land development, and human interactions are high and inevitable. However, identifying and monitoring risk, developing response plans, and taking timely action can help reduce risk and keep the urban forest sustainable and in the best possible condition. The following sections provide a summary of the most pressing current and potential future threats to Greenbelt’s tree canopy. Overpopulation of Callery Pear This popular landscape tree is now well known as a highly invasive, non-native plant. Progressive communities are banning its use and undertaking public education and even eradication programs. While Callery pear is an attractive tree that is tolerant of urban conditions, it has many negative attributes, and this undesirable species comprises almost 30% of Greenbelt’s public tree population. The Maryland Invasive Species Council, the Maryland Department of Natural Resources, and the Maryland Cooperative Extension Service have officially declared Callery pear an undesirable, invasive plant that is “widely recognized by biologists and natural resource managers to degrade natural resources and/or negatively impact native species, and is known to have a negative economic impact on agricultural or natural resources.” The following consequences can result from the overpopulation of Callery pear in Greenbelt:

● The Callery pear’s progeny are aggressively invading field, forest edges, and other open areas in Greenbelt and surrounding areas, much like other introduced exotic plant species such as Amur honeysuckle.

● Ecological damage is being caused by pear as they displace native plant communities upon which wildlife is dependent.

● Streets, sidewalks, cars, and buildings are at risk from limb failures of this fast-growing, weak-wooded tree during rain and snow storms.

● There are increased economic costs due to vegetation management problems near roads or under power line rights-of-way.

● Pears are susceptible to the bacterial disease such as ‘fire blight’ which can spread to apple, crabapple, pyracantha, and other desirable landscape trees and plants. A gradual plan to phase out Callery pears in Greenbelt is incorporated into Next Step #1: Institute a Systematic Cyclical Care Program and #5: Define a Strategic Tree Planting Plan.

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Emerald Ash Borer There are an estimated 200 ash trees (Fraxinus spp.) in the public tree population which comprise 2% of all public trees. As ash are susceptible to the emerald ash borer (EAB) and this pest is present in the region, it is considered a threat within Greenbelt’s city limits. Greenbelt has employed efforts already to proactively remove and replace ash on public property, treating only high-value, high- visibility ash trees for long-term preservation. This is a prudent approach to managing the damage and risks EAB brings to Greenbelt. However, there is likely a much higher percentage of ash trees overall in the city on private property. Citizens will also need information on how to identify ash trees, signs of EAB infestation, and be informed on the risks of delaying action. This public outreach effort will minimize risk and encourage replacement of ash with ideal species after removal. This work is incorporated into Next Step #12: Develop and Implement an Outreach Plan. Other Pests and Diseases Bacterial Leaf Scorch is present in Maryland and causes problems in a number of large shade trees, including London planetree, sycamore, pin oak, red oak, shingle oak, and bur oak, among others. It is caused by Xylella fastidiosa and presents in premature leaf browning and defoliation. Symptoms appear in the summer and early fall and may begin on one branch. Infected trees leaf out normally the following year, and in late summer leaves of a few more branches turn prematurely brown. These events repeat themselves over a period of several years until the entire infected tree turns prematurely brown in fall and begins to show twig and branch dieback and tree decline. Because infected trees decline gradually, it may take from five to ten years until they have many dead limbs and branches and need to be removed. There is no effective long-term cure for bacterial leaf scorch. However, awareness of this disease is important for future management planning and new tree planting considerations. Asian Longhorned Beetle (ALB). Like EAB, ALB bores into, reproduces, and feeds on the living tissues of trees. Signs of ALB start to show about 3 to 4 years after infestation, with tree death occurring in 10 to 15 years depending on the tree’s overall health and site conditions. Infested trees do not recover, nor do they regenerate. In the U.S., known ALB host trees include all species of the following 12 genera: ash, birch, elm, golden raintree, horsechestnut/buckeye, katsura, London planetree/sycamore, maple, mimosa, mountain ash, poplar, and willow. In Greenbelt, this range of host trees represents over 31% of the public tree population. In Maryland, the Maryland Department of Agriculture has deemed ALB a “Red Alert Species.” While ALB is not established in Maryland, infestations have been found as close as New Jersey and New York City. ALB is currently regulated by state and federal law. Gypsy Moth. This non-native insect has been a statewide threat to public and private landscape and forest trees in Maryland for decades. Mode of tree damage is rapid defoliation through feeding. However, oak is the preferred genus, as it is known to consume over 400 kinds of plants. This enables the caterpillars to continue feeding on other trees after the oaks are all denuded. Repeated defoliation can weaken trees and create stress that leads to tree decline and death. Over 25% of Greenbelt’s public tree population is susceptible to gypsy moth damage, as the insect prefers these trees: Betula (birch), Malus (crabapple), Picea (spruce), Pinus (pine), Populus (poplar), Quercus (oak), Salix (willow), and Tilia (basswood). Methods to address these tree health issues are discussed in Next Step #4 Refine a Plant Health Care/Mature Tree Care Program.

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Lack of Diversity Leading to Decline of Current Urban Forest Without proper care and management, an urban forest can decline over time. While decline may seem slow, the progression will be steady. Sustainability is the goal for urban forests. Sustainability is achieved by having diverse species and diverse ages and giving trees proper and timely care. Based on estimates from the inventory, nearly 75% of the public tree canopy is comprised of only 4 genera. Additionally, almost 86% of Greenbelt’s public trees are between 1 and 17 inches in diameter. In traditional forestry terms, this effectively means Greenbelt has an “even-aged stand” of public trees that is nearly a monoculture. These two conditions, in combination with tree loss and damage from insects and disease, storms, and potential land development, will set Greenbelt’s urban forest into a pattern of decline unless proactive intervention is initiated now. Efforts to correct and improve biodiversity in Greenbelt’s public trees is covered in multiple Next Steps #1: Cyclical Care, #2 Tree Inventory Completion, and #5 Strategic Planting Plan. Availability of Management Resources Greenbelt is lacking in asset data and formal management processes critical to ensuring the best care. Despite Greenbelt’s current efforts in the urban forest, the lack of complete and reliable inventory data, along with no systematic care cycle and canopy goal in place, make effective asset management difficult. These gaps are primarily attributed to lack of resources to institute those practices. The case for an increase in resources is made throughout the 12 Next Steps in the following section. A recommended budget to support the implementation of these steps can be found in the subsequent funding section. Land Development Municipal governments are often pressured to encourage and plan for greater population, economic growth, and expanded urban services, yet respond in a way that ensures cities remain livable. Urban forests play a critical role in responding to these current and future challenges. Considering the urban forest in all phases of development, from planning to construction, and finding adaptation solutions that protect and enhance, the urban forest will yield multiple benefits in the long term. During land development, trees should be considered as valuable green infrastructure solutions that can be highly cost-effective and produce benefits that ‘grey infrastructure’ solutions cannot. The future of Greenbelt as a city and of its urban forest appears to be one of growth and change. The potential is their large development, whether through the relocation of federal agencies, residential development at Beltway Plaza, or redevelopment of commercial areas. If this type of development occurs, there will be associated needs for residential housing, commercial areas, and public services. These large-scale developments often negatively impact the tree canopy. In addition, the forest preserves located within Greenbelt are not protected in perpetuity. Planned land development coupled with unprotected forest preserves combine to further increase the potential for urban tree canopy loss in Greenbelt.

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Greenbelt’s trees and other green infrastructure are important assets and are not just buffers between established and developing areas. The urban forest will be central to delivering amenity and ecosystem services and ensuring that the new growth and development of the city is functionally and visually integrated with the existing urban fabric. Citizens and city leaders should not lose sight that trees, figuratively and literally, are what makes Greenbelt ‘green.’ Methods to address these potential threats to tree canopy are discussed in Next Step #4 Refine a Plant Health Care/Mature Tree Care Program, #6 Update the Tree Protection Ordinance, #8 Continue Working Toward a Complete Street Policy, and #9 Address the Future of the Forest Preserves.

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VISION FOR GREENBELT’S URBAN FOREST The need for a healthy tree canopy is clear, and the threats facing Greenbelt’s urban forest are important to address. Before mapping out strategies to move forward, a vision for the future must be clarified. City staff and the Advisory Committee on Trees set Greenbelt’s vision for the future urban forest as follows: Greenbelt’s trees are iconic features of this historic community, creating an urban oasis that provides a high quality of life to residents. Our vision is to develop a tree master plan for streets and other public areas in the City of Greenbelt. This plan will provide for the care, preservation, pruning, planting, and replanting of trees. The tree master plan will also foster the sustainability of Greenbelt’s urban forest. Our goal is to maintain and expand upon this legacy, both today and for future generations. This vision statement can be used as a tool to evaluate future efforts and projects. When considering which initiatives or where to invest, the question can be asked: “Does this effort advance the movement toward Greenbelt’s future vision?” NEXT STEPS The recommended next steps are intended to serve as practical solutions to achieve Greenbelt’s vision for a healthy urban forest. These steps are systemic and consider the context of the conditions and threats affecting Greenbelt. Since a significant portion of Greenbelt is covered with tree canopy (over 60%), preservation should be the primary focus over the coming years, handled through proactive and ongoing investment and care. The 12 Next Steps listed here were made by synthesizing Greenbelt’s inventory and urban tree canopy data, the urban forest management program’s current standard operating procedures, the Public Works Department’s Strategic Plan, the Sustainability Plan Framework For The City of Greenbelt, the city’s code of ordinances, the American Public Works Association’s Guidance Statement on Quality Management of the Urban Forest, and current arboricultural industry standards and best management practices. 1. Institute a Systematic Cyclical Care Program 8. Continue Working Towards a Complete Streets Policy 2. Complete the Tree Inventory 9. Address the Future of Forest Preserves 3. Develop a Formal Risk Management Program 10. Explore Options for Wood Waste Utilization 4. Refine a Plant Health Care/Mature Tree Care Program 11. Increase Resources for Urban Forest Management 5. Define a Strategic Tree Planting Plan 12. Develop and Implement an Outreach Plan 6. Update the Tree Protection Ordinance 7. Reduce Conflict Between Trees and Utilities

Davey Resource Group 16 November 2018 Each of these recommendations is discussed in greater detail in the following pages. A timeline of tasks to complete has been prioritized into a five-year plan, along with potential funding needs. Why Prune Trees on a Cycle? 1. Institute a Systematic Cyclical Tree Care Program Pruning trees on a systematic and consistent cycle of 5–7 years has been shown to improve the condition of Reactive tree care is inefficient, as it waits for citizen service requests, the city-wide tree population significantly. One study or doesn’t act until after storms or when a tree dies. Such a system is (Miller and Sylvester 1981) examined the frequency of inefficient and can lead to increased liability and a decline in the pruning for 40,000 street trees in Milwaukee, WI. A condition of the urban forest. Proactive management plans have been decline in tree health correlated directly increases to the shown to reduce long-term care costs, increase public safety, provide length of the pruning cycle (as shown in Figure 7). When more predictable workloads and budgets, reduce utility outages from pruning was not completed for more than 10 years, the storms, and improve the health and appearance of the urban average tree condition was rated 10% lower than when environment. trees had been pruned within the last several years. Proactive tree work is typically performed as part of a cyclical care Miller and Sylvester suggested that a pruning cycle of program in which individual tree health and form are assessed five years is optimal for urban trees. throughout the city on a regular basis. Every tree in the inventoried population is regularly visited, assessed, and maintained. Greenbelt has been making efforts to care for public trees proactively for a number of years now. As part of the current program, over 200 trees are pruned annually as identified by staff during the course of their daily work or in response to citizen calls. However, handling pruning care in an ad hoc way such as this, not all of the pruning maintenance needs of a tree are addressed when service requests or needs are resolved. For example, only select branches required to resolve the concern (i.e., removal of broken hanging branch, raising of the crown, removal of branch obstructing a sign or building, etc.) are addressed, leaving other “routine pruning” work, like structural pruning, detailed health assessments and more, to be completed in an effort to resolve as many service requests as possible. In addition, often times when this method of care is used, tree care work and future needs are not officially recorded but known and held by field staff. As staff turns over, institutional knowledge that can greatly affect the longevity of the urban forest, as well as public safety, Figure 7. Relationship between average tree can be lost. A more systematic method is essential to long-term health condition class and the number of years since last and longevity of Greenbelt’s urban forest. pruning (adapted from Miller and Sylvester 1981).

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Clearly-defined management units, along with each tree’s health, risk level, and maintenance need, are determined and acted upon on a regular, cyclical basis using this method. All work and findings are recorded, and inventory data are also updated at the same time. The initial years of the cyclical tree care program recommended for Greenbelt are summarized below to establish a pattern:

Year One Sector 1: Inventory Update (inspection of every public tree and record of vacant planting sites) Citywide: Large mature tree inspection and remedial treatment as needed (see Strategy 4 for specifics); storm damage response; citizen requests

Year Two Sector 1: Tree Care (Pruning, Removals [20 pears, any others in need of removal due to health or storm damage incurred], Plant Health Care treatments as needed, planting, and public engagement) Sector 2: Inventory Update Citywide: Large mature tree inspection and remedial treatment as needed (see Strategy 4 for specifics); storm damage response; citizen requests

Year Three Sector 1: Year 1 of Young Tree Care Sector 2: Tree Care (Pruning, Removals [20 pears, any others in need of removal due to health or storm damage incurred], Plant Health Care treatments as needed, planting, and public engagement Sector 3: Inventory Update Citywide: Large mature tree inspection and remedial treatment as needed (see Strategy 4 for specifics); storm damage response; citizen requests

Year Four Sector 1: Year 2 of Young Tree Care Sector 2: Year 1 of Young Tree Care Sector 3: Tree Care (Pruning, Removals [20 pears, any others in need of removal due to health or storm damage incurred], Plant Health Care treatments as needed, planting, and public engagement Sector 4: Inventory Update Citywide: Large mature tree inspection and remedial treatment as needed (see Strategy 4 for specifics); storm damage response; citizen requests

Year Five Sector 1: Year 3 of Young Tree Care Sector 2: Year 2 of Young Tree Care Sector 3: Year 1 of Young Tree Care Sector 4: Tree Care (Pruning, Removals (10 pears, any others in need of removal due to health or storm damage incurred), Plant Health Care treatments as needed, planting, and public engagement Sector 5: Inventory Update Citywide: Large mature tree inspection and remedial treatment as needed (see Strategy 4 for specifics); storm damage response; citizen requests

Davey Resource Group 18 November 2018

Year Six Sector 1: None Sector 2: Year 3 of Young Tree Care Sector 3: Year 2 of Young Tree Care Sector 4: Year 1 of Young Tree Care Sector 5: Tree Care (Pruning, Removals [20 pears, any others in need of removal due to health or storm damage incurred], Plant Health Care treatments as needed, planting, and public engagement Sector 6: Inventory Update Citywide: Large mature tree inspection and remedial treatment as needed (see Strategy 4 for specifics); storm damage response; citizen requests

Continue through all sectors and repeat.

Initiating a Cyclical Care Program at the Current Budget. Greenbelt’s public tree population is estimated to be approximately 5,000 trees. If an ideal cycle is instituted of 5–7 years (see Why Prune Trees on a Cycle? inset on page 18), then over 700 trees per year would need to be closely inspected and maintained in a proactive maintenance program. Admittedly, this number of trees is well over the current level of maintenance performed (240 trees pruned per year currently). However, it is possible to begin a cyclical maintenance program with the current funding and staff levels. For instance, without a budget increase or resource reallocation for tree maintenance, the city can be initially divided into 15 sectors or management units. The same yearly tasks described above could be followed until all 15 units were complete. In Year 16, there should be less tree maintenance required in the tree population, meaning two or more units could be combined and all the tree maintenance work would be performed in those two units for the same budget. The next cycle of PM could, therefore, be only 7 to 8 years long. After that, the city and its urban forest should be well positioned to maintain a 5- to 7-year PM rotation of 6 management units (2 each in the West, East, and North). For now, Greenbelt should set a goal for a preventive maintenance rotation and start the cyclical care program as soon as possible, as it will take time to achieve the goal. To implement a cyclical care plan, the following steps are needed:

● Adopt a tree maintenance program goal of cyclical tree care where all street trees and trees in active park areas are inspected and appropriately maintained ideally on a 5- to 7-year cycle.

● Divide the city into management units for preventive maintenance that corresponds with the desired cycle (i.e., 5 units, 6 units, 7 units), and then further divide those into sub-units appropriate for the current maintenance budget.

● Perform all tree maintenance work to ANSI A300 standards. These standards will ensure that trees are thoroughly maintained beyond deadwood removal and that pruning is completed to improve structural integrity. The standards will also reduce the incidence of disease and ensure that clearance is achieved for sidewalks, streets, signs, and lights.

● Record all inspections and work performed in the existing tree inventory database.

Davey Resource Group 19 November 2018

2. Complete the Tree Inventory Tree inventory data for public trees is critical for efficient and effective management of the urban forest. Decision making, budgeting, and policy development for Greenbelt’s public trees need to be data-driven. A partial inventory of street trees was conducted in 2013 by city staff and volunteers, collecting data on location, species, size, and general condition. While this is a good start, the current inventory is estimated to include only 50% of all public trees and no vacant tree planting sites in Greenbelt. In addition, there are inventory data gaps that impede staff to manage risk and monitor the public trees effectively. With expanded data fields and a complete inventory of public trees, Greenbelt will be able to use the data for long-range, proactive planning to ensure the continued beauty, vitality, safety, and survival of all public trees. Complete inventory data will also inform the city of its maximum stocking level; therefore, the actual number of trees that can be planted will be known. Planting programs and resources can then be appropriately allocated for a no-net- loss policy. Since completing the inventory is a priority, the city may want to consider contracting this task to a professional urban forestry consultant or firm. The professional services provided would assure the city that comprehensive tree and planting site attributes are collected, risk is assessed per industry standards, and that appropriate maintenance recommendations are made. The consultant can also provide accurate GPS/GIS location data for all trees and planting sites. Consider the following when completing the inventory for existing trees and vacant planting locations on all streets, parks, and other public properties:

● Expand the data fields to include those recommended in ISA’s Best Management Practices for Tree Inventories, Second Edition, such as risk level, primary maintenance, secondary maintenance, presence of utilities, grow space characteristics, etc.

● During the inventory, a Certified Arborist should assess risk levels and make maintenance recommendations.

● Manage the data in an appropriate tree inventory data management software program that is compatible with current agency capabilities and procedures. Many standalone customized software programs are available. Modules compatible with municipal GIS asset management programs are also available. Some programs are free, and others range from $1,500–$2,500 for an annual subscription to an online platform (see Appendix D for inventory data management program information).

● The inventory should be immediately updated when maintenance and/or planting work is performed. The inventory, in its entirety, should be updated at least every 10 years. But a more desirable and efficient approach would be to continually update the inventory on an ongoing basis by re-inventorying the portion of the urban forest that is receiving preventive maintenance during the cyclical maintenance program.

Davey Resource Group 20 November 2018

3. Develop a Formal Risk Management Program Greenbelt should establish a documented process for assessing, monitoring, and mitigating high-risk public trees. While trees that have been properly cared for throughout their life generally pose little safety concern, there is always some risk associated with maintaining large-diameter, over-mature trees in public use areas. The documentation of Greenbelt’s risk management program can be a simple three- to five-page document (such as the Risk Management template provided in Appendix E, or a comprehensive manual that guides the city and urban forestry safe with detailed standard operating procedures). Any documentation should include input from forestry staff, the controlling utilities, and risk management and legal staff. It should also contain a map of “hot spots” or areas of importance to public safety. In the very rare instance of litigation occurring as a result of tree or limb failure, the City of Greenbelt’s risk management policy will be able to demonstrate that it has implemented a “reasonable” tree-risk management program. What is reasonable is a function of the resources available in its forest management program, and the city as a whole. In other words, the level of tree care in one community may not be reasonable for another because of limited staff, equipment, and budget. Types of Risks Trees pose two primary types of risk: risks specifically during and after severe weather events, and risks from poor condition and the results of insect and disease infestation. ● Risk Management Related to Tree Condition and Location. Trees present risks when large deadwood and structural defects are present, root damage has occurred, and when insect and disease infestations weaken and damage trees. Additional risk management responsibilities include clearing leaves and woody debris from gutters and storm drains, sidewalk, street, and building clearance, line-of-sight conflicts for street and safety signage, blockage of street lamps and traffic lights, and conflicts with overhead and underground utilities. At its core, a municipality’s risk management program’s focus is to identify those features of the tree population that pose the highest potential risk to the public and property, and then concentrate on available resources to reasonably mitigate risk. A defensible risk management program should establish and define the level of care that is appropriate given a community’s available resources for a specified time period. When properly developed, documented, and executed, a tree risk management program will elevate the effectiveness and responsiveness of the city’s community forestry program. ● Risk Management Related to Severe Weather Events. When catastrophic disasters, such as tornadoes, ice storms, hurricanes, and severe straight-line winds strike an urban area, thousands of cubic yards of all kinds of debris are produced. Trees and vegetation can account for approximately 30% of this debris volume. Beyond the task of collecting and disposing of tree debris, the city has additional risk management considerations including threat to life from hanging limbs and uprooted trees, hindrance to life- saving efforts by blocked streets and driveways, power outages and power restoration efforts, and personal and public property damage. The impact of these additional tree-related considerations is not always quantifiable but can overwhelm public services and slow down the short- and long-term recovery process.

Davey Resource Group 21 November 2018

Storm hazards are greatly reduced through proper planting, preventive maintenance, and systematic risk reduction. However, more is needed. When disasters occur, an emergency plan can provide solid data and facts, and detailed policies, procedures, and protocols to ensure service continuity and timely recovery and restoration. The development and adoption of an urban forestry emergency response and preparedness procedures increase the efficiency and productivity of emergency storm response operations. Pre-Storm. Most of the work in pre-storm disaster management is the proactive maintenance of trees described in Recommendation #1. This will greatly reduce the number of hazards present and ultimately make the urban forest more storm- ready and less susceptible to damage. However, work systems can be planned in advance that serve as an addendum to a city- wide emergency management plan, or simply as a summary of the urban forestry division’s expected role in a disaster for staff education and preparedness purposes. Plans can include:

● Chain-of-command description and clarification ● Method of communication to be used in emergencies ● A triage process for tree debris removal (often clearing critical lanes and access to hospitals and other key sites first) ● Designated pre-set sites for debris to facilitate quick and safe removals ● Prearranged tree pruning and removal contract agreements after disasters to avoid high-rate fees in last-minute situations Post-Storm. The first step in post-storm urban forest management is to implement the triage process and clear major thoroughfares and dangerous situations in a methodical and prioritized order as described above. However, it shouldn’t end there. After this initial work, a window of time exists where many trees are prematurely removed, often on private property, by property owners approached by uneducated contractors offering to remove any trees that experienced any damage. Many trees can withstand high winds and storm damage and rebound after severe storm events. However, after a storm, trees with no leaves may appear dead or dangerous to the untrained eye, and unwarranted removals may occur. Forward-thinking disaster plans can include a communication plan to explain this to the public, along with a system or access to expertise to help property owners safely determine which trees can be saved. A predefined communications plan will make major strides in tree preservation in the weeks after a storm. Finally, after a storm event, the plan should be updated and modified to increase efficiency and reflect any organizational changes. No matter whether tree risk is from a storm event or natural lifecycle of a tree, inspections should be performed by a Certified Arborist and follow the ISA’s BMPs and ANSI A300 (Part 9) “Risk Assessment” Level 2 standards. These standards will ensure the inspection reveals complete information about the health and structural stability of the trees.

Davey Resource Group 22 November 2018

Next Steps. Two broad goals are required of every well-defined tree risk program: establishing a reasonable program and clearly documenting the program. The first goal addresses the risk of physical harm. The second goal allows a community to defend its program if litigation occurs, thus minimizing the financial risk. Both goals are realized by initiating policies and completing tasks at both the microscale and the macroscale. Microscale refers to the community’s policies towards individual trees; macroscale refers to community policies directed at managing the total urban forest.

● Goal 1—Establish a Reasonable Community Tree Risk Program: design and implement a program that identifies and mitigates the highest risk features in Greenbelt’s tree population. Microscale. Promote activities that increase staff knowledge, skills, Three Levels of Tree Inspection and experience in evaluating individual trees for risk. The following tasks are examples for achieving the microscale element of this goal. Performed most often by walking or driving by a tree (often termed a “windshield inspection”) and looking 1. Conduct repeated hazard tree assessment training for all staff for obvious defects, hazards, or problems. This is who work with trees. typically done when first looking at trees to note any 2. Require the arboricultural staff to become certified by ISA for obvious problems or targets. tree risk assessment. Level Two: Basic Assessment involves a detailed 3. Fund staff attendance to regional, state, and national inspection (from the ground) of the site and the tree, arboriculture conferences. including the root zone, the trunk, branches, and the upper canopy. This also considers potential targets 4. Conduct short, monthly “tailgate” refresher courses on proper that may be impacted by tree failure and the possible arboricultural practices, insect and disease identification, consequences of failure. This is the most common hazard assessments, chainsaw safety, etc. form of assessment performed by arborists. Macroscale. Promote activities that allow Greenbelt to create and Level Three: Advanced Assessment is an extension of manage risk at a reasonable level for all of the trees under its a Basic Assessment, Level Three. Inspections are stewardship. There are five steps to defining the level of care that is performed to provide additional information on appropriate for Greenbelt. These steps are as follows: which to base a risk rating and form recommendations for mitigation. Specialized tools are often used in an advanced assessment and climbing the tree for closer inspection of defects is common.

Davey Resource Group 23 November 2018

o Assess the Tree Population. Greenbelt should strive to reduce the most problematic features in the tree population. A complete tree inventory is the best tool for identifying these features. Risk increases when combinations of the following five items occur: problem species, large diameter, poor condition, structural defects, and high target. Perform Basic Assessments (Level 2), and Advanced Assessments (Level 3) if indicated by the Level 2 findings, on mature trees annually, or at least during the cyclical maintenance inspections. Perform inspections of mature trees after severe weather events.

o Evaluate the Resources Available to Manage the Tree Population. Once a refined list of risk trees has been established, assess the budget, equipment, and labor force to determine the level of care that is possible for Greenbelt.

o Create A Risk Policy Statement. A strong policy statement identifies the overall mission of Greenbelt for any high-risk trees. The tree risk policy statement should include the following: - State the community’s understanding of its responsibility to maintain safe public areas and rights-of-way. - Identify the manager of the risk reduction program. - List any general constraints on managing hazard trees (i.e., financial or personnel constraints).

o Implement A Risk Management Plan. Once the first three tasks have been completed, Greenbelt should implement a risk management plan that defines a series of risk reduction objectives and associated actions to achieve each objective. The portion of the tree population with the highest probability of failure should be the initial target of any management strategy designed. Subsequent strategies focus on defining achievable monitoring programs of the complete urban forest.

o Evaluate the Program. On an annual basis, staff should meet and discuss any significant tree failures from the previous year. In addition, staff should review whether the outcomes defined in the risk reduction plan are being met. If they are not being met, what changes have to occur to allow the outcomes to unfold?

● Goal 2—Establish a Defensible Program: Greenbelt must be able to articulate and defend the specific program it has developed. Documentation is the easiest way to achieve this. Microscale. Document that the staff is fully qualified to assess trees for risk and to make recommendations on how to best mitigate that risk. For each employee, the following actions apply:

Davey Resource Group 24 November 2018

1. List any, and all specific training courses attended. Include the title of the course, the date, the duration, and any applicable CEU credits. 2. List any specific certifications achieved. Include the title, affiliation, and date. 3. List all conferences and workshops attended. Include the title, location, date range, and sessions attended. 4. List all “tailgate” training attendance. Include the subject, date, and duration. 5. List all forensic discussions attended. Include the location, date, species, diameter, type of failure, and the final determination by staff of what caused the failure to occur. Macroscale. Document the outcomes from each of the five steps from the macroscale part of Goal 1.

o Summarize the assessment of the tree population. Summaries should include distributions for species, condition, diameter, and defects. The high target areas of the community should be mapped. Identify in writing all of the problem areas within the tree population.

o Summarize the fiscal, staff, and equipment resources available to Greenbelt.

o Document the tree risk policy statement.

o Document all objectives and actions defined in the tree risk management plan.

o Document the annual program review. Include the date of the meeting, minutes, and outcomes. All documents created in Goal 2, from both the microscale and macroscale elements, should reside in a tree risk management manual. The manual allows easy access for staff and establishes the basis for articulating Greenbelt’s tree risk program. A management program’s overall focus is to identify those features of the tree population that pose the highest risk to the public, and then concentrate on the available resources to mitigate those features. A long-term risk reduction program defines a level of care that is appropriate within a community’s available resources. As a result, a defensible program will have been established. A comprehensive tree risk management program should be developed and should include both regularly inspecting trees to identify risk concerns and initiating the timely performance of corrective actions to address tree risk concerns. More information about risk assessment, protocols, and best management practices can be found in Appendices A–C. The city should develop an emergency response and recovery plan for the urban forest that provides information about general tree risk reduction and gives directions to city agencies on how to best proceed during an extreme storm emergency. The plan should be based on industry-accepted best management practices and appropriate national standards (i.e., ANSI A300 and ANSI Z133) and should include information on priority tree risk zones (e.g., major road arteries, hospitals), available staff and equipment resources, and inventory analyses.

Davey Resource Group 25 November 2018

To address overall tree risk in Greenbelt, a Tree Risk Management Manual that includes the following information should be developed.

● Summary of the assessment of the tree population including distributions for species, condition, diameter, and defects. ● Summary of current practices and the fiscal, staff, and equipment resources available to the city. ● Consistent and accepted terminology to use in risk assessments and establish an acceptable threshold of risk. ● Maps of the high target areas of the community and the problem areas within the tree population. ● Maps or guidelines for monitoring and conducting visual risk assessments based on high target areas and following storms to assess impacts or changes in tree risk. ● Specific actions, procedures, and objectives to address tree risk once it is identified. ● Procedures for annual risk management program review. ● Reference materials for city staff use, such as forms for risk tree assessment, debris estimation, work tracking, etc. ● Training in risk assessment and management should be considered. Beyond forestry staff, multiple city departments or staff can likely impact or assist in assessing tree risk concerns. A training program on urban forest risk identification, avoidance, and reduction would benefit Greenbelt. 4. Refine a Plant Health Care/Mature Tree Care Program Based on the many benefits trees provide, a purposeful plant health care program should be established. A successful program schedules regular inspections and proactive care. This is important for all trees in Greenbelt, but especially for the large mature trees in the community. Overall Tree Population Health Care An integral part of tree management is being highly aware of invasive insects and diseases in the area and knowing how to best manage them. Considering the species distribution from the inventory data, much of Greenbelt’s urban forest is at risk from invasive insects or diseases. The following recommendations are geared towards improving plant health care in Greenbelt’s urban forest: • An integrated pest management (IPM) plan and efforts should be established that focus on identifying and monitoring threats, understanding the economic threshold, selecting the correct treatment, properly timing management strategies, recordkeeping, and evaluating results. • Greenbelt forestry staff and contractors should be trained to detect signs and symptoms of potential infestations and should be prepared to act if a significant threat is observed in its tree population or a nearby community.

Davey Resource Group 26 November 2018

• Greenbelt should provide education to property owners about significant insect and disease threats and confirmations. Since the majority of trees that comprise the city’s urban tree canopy are on private property, it is vital for the city to educate the public on how to detect insect and disease threats, provide information about management and treatment options, and relay the importance of reforestation in the event that trees are removed due to insects and disease. Mature Tree Health Care It is estimated that there are nearly 700 mature, large-diameter (greater than 18” DBH) trees on public property in Greenbelt. Over half of these trees are desirable oak and maple species. These large crown trees produce the most benefits for the city and the citizens, and they contribute greatly to Greenbelt’s overall ambiance and sense of place. Mature trees growing in an urban environment face many challenges that threaten their vigor and increase risk—poor soil quality, restricted rooting area, air pollution, increased temperatures, construction damage, vehicular accidents, soil compaction, inadequate/inconsistent water, and stress-induced insect and disease infestations. To protect and preserve these almost irreplaceable assets, the city should consider inspection, protection, and plant health care programs that specifically target the city’s mature trees. Specific recommendations are as follows: • Enforce current tree protection regulations and hold people accountable for damaging any mature tree. • Implement a mature tree plant health care program that includes the following:

o Identifying all mature trees in Fair or better condition that will receive greater attention and care.

o Performing core aeration and radial trenching for select mature trees in parks to overcome the stress of compaction.

o Using tree growth regulators, particularly for mature street trees and trees damaged by construction, to help overcome root loss and nutrient deficiencies, and to decrease the need for and lessen the impact of frequent utility pruning.

o Conducting soil tests to determine whether nutrient deficiencies exist and then correct any deficiencies with soil injected slow-release fertilizer.

o Monitoring for insect and disease threats as part of the cyclical care program and taking appropriate action. • Establish partnerships to fund and accomplish the mature tree care program. The utility company may support tree growth regulator applications for trees under their lines; businesses may join an “adopt-a-tree” program for significant trees in parks and in commercial areas; citizens may help water mature street trees during times of drought. • Authorize the use of compensatory damage payments, in lieu payments, sale of municipal wood products, etc. to fund elements of the mature tree care program.

Davey Resource Group 27 November 2018

5. Define a Strategic Tree Planting Plan As is well known in Greenbelt, reliance on a few species is risky. Overreliance on a limited number of species leaves the community vulnerable to threats from pests, disease, and stress due to climate change. A greater range of species provides greater resilience and long-term stability for the forest as a whole. Additionally, a robust urban forest also features age diversity, with species of varying life spans and growth rates. A uniform age profile makes it likely that many trees will decline and senesce at the same time. Some areas of the urban forest in Greenbelt are vulnerable due to a lack of diversity in terms of both species and age distribution. Corrections and adjustments in both species diversity and age/size ranges should be planned and accounted for over the next decade. Greenbelt Tree Planting Plan A simple master tree planting plan based on an updated and complete inventory data (including vacant planting sites) will ensure proper species diversity as trees are removed and new planting campaigns commence. The following considerations should be factored into a planting plan. • Annual Planting. Annual planting has been incorporated into the cyclical care program (see Recommendation #1). The total number of trees to be planted each year is up to the city based on available budget; however, no matter the quantity, they should be spaced out geographically each year to avoid poor age diversity by neighborhoods. • Species Choice. Best practices in urban forestry biodiversity (discussed on page 9) require that planting of pears be suspended completely (which is currently the case), while planting of maple or oak on public property should be scaled back until inventory updates reveal that these genera are below the suggested threshold. Private property owners and developers should be encouraged/required to plant other species as well. Plant large canopy trees whenever and wherever site conditions will allow. • Annual Removals. Aside from removals based on safety needs, Greenbelt should systematically remove at least 20 pear trees (Pyrus) at a minimum each year until this invasive tree comprises less than 10% of the total public tree population. However, all pears should ideally be removed (either by design or natural attrition) within the next 10 years. This can be accomplished by taking the following actions: o Making it a policy that pears on any public property are immediately removed and do not receive corrective pruning/treatment if any portion of the crown is damaged by a storm or by a disease, such as fire blight. o Educate property owners about the threat pears pose to natural forest lands and ask for “volunteers” who would be willing to have the street tree pear removed and replaced with a more suitable, non-invasive tree species. o Do not allow any developer to plant pear trees anywhere on the property whether it is a commercial or residential development project. Additionally, require developers to remove any pears on the development site as a condition of the permit. o Coordinate with PepCo to remove select pears from streets when they are performing line clearance work.

Davey Resource Group 28 November 2018

6. Update Tree Protection Ordinance For a municipality to legitimately claim to have a comprehensive urban forestry program, a tree ordinance should be in place that establishes standards and sets guidelines for the management of trees by the municipality and the treatment of trees by private entities. A tree ordinance is the legal framework within which local tree management activities are conducted for the general welfare. Greenbelt has an ordinance in place - Chapter 12, Article VII – that generally provides for the protection and proper treatment of street and park trees but lacks important elements that should be included to create a stronger ordinance that reflects the community’s goals and current industry standards. The following recommendations are made for Greenbelt to consider strengthening the existing ordinance structure and language. • Revision 1. Include a “Goal Statement” to present Greenbelt’s vision and identity with respect to its tree resources. This may include one of the following statements: “Protect and promote the health, safety, and welfare of the public, both current and future citizens, by protecting the tree canopy,” or “Safeguard and enhance the natural environment and resources of the city.” • Revision 2. Expand the Definitions section to include more terms that are used in the ordinance, even including what a ‘tree’ is so that there can be no misunderstanding. • Revision 3. Include acceptable and unacceptable basic performance standards for the treatment of public trees. The language used to define these practices should be clear and quantifiable so that the ordinance will be enforceable. • Revision 4. At a minimum, refer to these current national arboricultural industry standards: ANSI A300 Tree, Shrub, and other Woody Plant Management – Standard Practices, ANSI Z133.1 American National Standards for Arboricultural Operations – Safety Requirements, and ANSI Z60.1 – American Standard for Nursery Stock. • Revision 5. Be cautious of including too many details, as materials and methods of tree care, planting, and management often change and this would render the ordinance out-of-date. Specific details about items such as allowed or prohibited species, soil volumes, plant sizes, clearance requirements over streets and sidewalks, etc. should be included in a separate manual or best practices guidance document that can be more easily updated than the ordinance. However, the ordinance should reference this document. • Revision 6. Include a section on “Prohibitions” such as “No person shall damage, prune, remove, or plant any tree or shrub in any public street or other public place without having first obtained a permit from the Public Works Department. Damage to public trees includes, but is not limited to, construction and excavations, vehicular accidents, vandalism, adhering advertisements or electrical wires, animal damage (tied to or damaged by), allowing toxic substances to come in contact with soil within the dripline (gas, brine water, oil, liquid dye, or other substance) deleterious to tree life.” • Revision 7. Designate who is responsible for enforcing and monitoring the performance standards.

Davey Resource Group 29 November 2018

• Revision 8. Include the authority of the city to collect compensatory payments for unauthorized tree removal or damage. Sample language might be: “No person shall remove any public tree without replacing such tree with a tree of equivalent dollar value in the vicinity of the removed tree. The value of a tree shall be determined by the city arborist considering the species, locations, size, and condition of the tree. If no suitable location exists in the vicinity of the tree removed or if the replacement tree is of lesser value, the person causing the tree to be removed shall make a compensatory payment to the City of Greenbelt equal to the difference in value between the tree removed and any replacement tree. Any public tree that is determined by the city arborist to be damaged, but not sufficiently to justify its removal, shall be considered to be devalued. The amount of devaluation shall be paid to the city by the person causing the damage. Compensatory permits shall be paid into a fund established for that purpose and restricted to use for urban forestry programs. Compensatory payments may be in addition to other penalties.” • Revision 9. Create or clarify a tree permit system that explains the process of getting approval for persons or entities other than the city to remove, prune, plant, or perform any activity affecting public trees. • Revision 10. Greenbelt may also want to include additional provisions that are needed to reach the community’s goals and address unique local issues that may include the following: o Utility trimming. Defines requirements and responsibilities (further discussed in Recommendation #7). o Guidelines for species diversity. Sets basic standards for species diversity and directs the community to keep updated, specific guidelines in its tree management plan. o Updated land development plan review process. Define the process that developers must follow to have their plans for new development reviewed/approved. o Tree replacement. Establishes how trees lost to development should be replaced. Some processes could be requiring developers to set aside wooded areas, off-site reforestation, percentage replacement or flexible, no-net-loss formulas. o Invasive insect and disease response. Defines the city’s authority to direct removal/treatment of trees on both public and private property if a significant insect or disease threat exists in the city. o Landmark and historic trees. Establishes what defines landmark and historic trees and how they should be managed. 7. Reduce Conflicts Between Trees and Utilities Conflicts between trees and utilities date back to the 1830s when the first telegraph lines were erected in Baltimore. Conflicts still exist today because of previous poor tree selection and placement that create the potential for utility outages. Large shade trees under utility lines are then severely pruned for line clearances of 15 feet below high-voltage lines and total clearance above (as determined by vegetation management regulations adopted by the Maryland Public Service Commission). Additionally, PepCo, Greenbelt’s primary utility provider, has a policy to remove a tree if required pruning causes a loss of more than 25% of a tree’s crown. These practices are consistent with standards and practices outlined by the American National Standards Institute (ANSI) A300. ANSI A300 is incorporated into laws and regulations that apply to vegetation management, including the Maryland Tree Expert Law and RM43.

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That said, “collaborating with utility companies...for future work on City property” is a priority objective, as stated in Greenbelt’s 2016 Public Works Strategic Plan. Currently, PepCo and the City of Greenbelt work closely together to address these challenges, but improvements can be made. The following recommendations are therefore provided to help achieve this objective: • Identify All Conflict Sites. As discussed in Recommendation #2, the city should complete and update its public tree inventory to show the locations of all public trees, the presence or absence of utility lines, the presence or absence of tree/utility conflicts, updated conditions and risk levels, and vacant planting locations. With this information, productive and clear communication can occur between the city and PepCo when planning tree maintenance and replacement planting projects. • Explore a cooperative effort to accelerate the removal of dangerous, declining, or nuisance trees under utility lines. The slow proactive removal of Callery pear can also be included in the plan, as the crowns of some of the more mature pears may now be within 15 feet of energized lines. • Institute a System of Constant Communication. The city and PepCo should regularly communicate about PepCo’s pruning cycle in the city. Mutually inspecting the circuits to be pruned well in advance of the utility crews’ arrival will allow both parties to resolve any issues and better communicate with affected residents and businesses. The city and PepCo can also meet annually to understand each other’s maintenance work plan, public outreach and education efforts, and tree planting projects. These meetings should result in communication where solutions to problems can be explored and resources needed to correct the situation can be identified. The city should request that PepCo consider using additional arboricultural and utility research and techniques available to provide more options for solutions to tree/utility conflicts. Examples include the conversion of multiple aerial lines into innovative cable design, and experimentation with different cross-arm dimensions, locations, and construction techniques to reduce the need for extensive pruning. • Consider revising the current Tree Ordinance to specifically address utility pruning and maintenance activities. Sample language could be: “When maintaining public trees, a public utility shall observe good arboricultural practices, as specified by the International Society of Arboriculture and the American National Standards Institute (ANSI) A300 Standards.” Or, it could state that “Public utility companies subject to the jurisdiction of the Maryland Public Service Commission may perform such pruning and maintenance and other work as necessary to comply with the safety regulations of said commission and to maintain a safe operation of their facilities without a permit or fee. However, they shall notify the City Arborist at least three working days (except in emergencies) prior to taking action. The City Arborist shall cause such pruning or other work to be approved and subsequently inspected, when appropriate, to ensure good pruning practices are followed. The City Arborist has the authority to stop any tree pruning or maintenance practices performed by a utility or their contractors if such practices are not being followed.”

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Or, it might state that “A general permit may be issued for routine utility pruning if pruning methods comply with International Society of Arboriculture and ANSI Standards. The City Arborist shall periodically examine utility work to assure compliance.” These statements, or others like them, placed in the tree ordinance would officially declare the city’s acknowledgement of PepCo’s important responsibilities, as well as the need to promptly communicate and follow professional standards during utility work. • Joint Outreach. PepCo is responsible for providing energy services to their customers in a safe, efficient, and reliable manner. The City of Greenbelt is responsible for responding to citizens’ needs, ensuring public safety, and improving the quality of life for all. Public outrage resulting from a round of severe pruning requires ever increasing communication between Greenbelt and PepCo. Ongoing messaging about the challenge of shared right-of-way space that highlights the city’s partnership with PepCo is critical. It should be pointed out in communications that everyone’s goals are reached by having trees pruned and removed to maintain safe and reliable energy systems in the short term, and planting compatible replacement trees near utility lines for a long-term solution. Education of the general public would be a highly effective method for mitigating many current and future tree/utility conflicts. Both the city and PepCo likely have basic education programs and materials available, but an expanded and jointly developed effort to disseminate information should be pursued. The primary message should focus on the fact that both the city and PepCo agree that trees and utilities are two valuable community assets and are important resources for Greenbelt’s development and sustainability, and that joint efforts are being made so that they can coexist. This messaging has been incorporated into Recommendation #12: Development and Implement an Outreach Plan. The city and PepCo should be united, consistent, and confident in their answers when citizens and businesses ask the following questions: o Can I plant this oak tree under the utility wires? o Can I get assistance to remove this old tree under the wires and to plant a new tree? o Where should I plant trees to improve my home’s energy conservation? Co-promotion of Advisory Committee of Tree’s (ACT’s) list of trees recommended under power lines is encouraged.

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8. Continue Working Towards a Complete Streets Policy The use of complete streets encourages the placement of trees within the right-of-way and makes sure they become a component of road infrastructure. Complete streets also have other benefits such as improved walkability and pedestrian safety. Instituting a complete streets policy in Greenbelt will provide an opportunity to add canopy and increase pedestrian safety every time any street within Greenbelt is redone. It is recommended that the city continue efforts to institute complete streets policies, like the conceptual Cherrywood Lane Complete & Green Street project study, completed in December 2015 (Figure 8). This is especially important to have in place in advance of future large potential developments.

Figure 8. One green street concept from Cherrywood Lane Study.

9. Address the Future of Forest Preserves and Their Larger Role in the Region Greenbelt is part of a larger corridor of natural areas situated at the southern-most position (adjacent to Fort Meade and Patuxent Wildlife Refuge) of a wildlife corridor that extends all the way to Baltimore. The name Greenbelt comes from the 800+ acres of forest that once surrounded the community when it was first built in the 1930s. Over the years, the forest lands were sold piece by piece until only approximately 200 acres remained. The loss of natural habitat, urbanization, and air and water pollution have all threatened the survival of many plant and animal species. With potential urban growth into and near forest preserves and other wooded sites, the likely loss of biodiversity from these threats becomes even greater, highlighting the need to seriously address biodiversity in Greenbelt and the role of its forest preserves in the larger region. Davey Resource Group 33 November 2018

The U.S. Department of Agriculture notes that between 1986 and 2006, the area between Baltimore and Washington D.C. lost over 3,000 acres of tree canopy. A citizens' group, the Committee to Save the Green Belt, formed in 1987, worked feverishly over the decades to save the woods from development until the City Council passed a unanimous resolution in 2003 to form the Greenbelt Forest Preserve (Greenbelt Forest Preserve 2017). The larger regional Baltimore-Washington Partnership for Forest Stewardship (BWPFS) was also created in 2006 to restore, conserve, and steward this larger scale landscape. Greenbelt is a member of this partnership, which also includes the USDA Beltsville Agricultural Research Center, the U.S. Fish and Wildlife Service Patuxent Research Refuge, NASA/Goddard Space Flight Center, U.S. Army Fort Meade, the Maryland Department of Natural Resources, and the Center for Chesapeake Communities (U.S. Department of Agriculture 2011). Then, in 2013, the Maryland Department of Natural Resources provided Greenbelt with a Forest Stewardship Plan to maintain and enhance forest health to advance Chesapeake Bay restoration efforts. These are all positive steps in maintaining and preserving forested land in Greenbelt. However, while gathering public input during the plan development process, the issue was raised that these preserves are not protected in perpetuity. They can still legally be sold and developed if needed. If this is indeed the case, this is something to monitor and consider options for a more permanent conservation solution in coming years. If Greenbelt’s forest preserves are further developed, there will be a significant loss of canopy and associated benefits. 10. Explore Options for Diversifying Wood Waste Utilization Greenbelt has made a commitment to be as sustainable as possible in all municipal activities, and to encourage residents to consider sustainable practices and habits as well. The city’s Sustainability Plan Framework has been drafted to guide the city, businesses, and residents to take actions that fulfill the community’s need yet do not deplete or harm resources and the environment. The proper care and use of green infrastructure, as well as recycling renewable resources, has already been identified in the Sustainability Plan as priorities and goals. The city’s Public Works Department is also committed to sustainability with respect to wood waste utilization. Greenbelt currently has a steady stream of wood waste from public trees generated by routine pruning, removals, leaf and brush collection, and storm damage clean-up. This waste stream may even increase in coming years based on the following factors: • A higher emphasis on proactive tree maintenance and risk management, resulting in a more rapid and steady rate of mature tree pruning and removal. • The confirmed presence of the invasive and destructive pest, emerald ash borer (EAB), as well as a threat of other exotic and invasive pests and diseases which are present in the region.

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Tree waste (wood and leaves) produced and/or collected from municipal maintenance operations is annually transported to a designated holding area and made into woodchips by a hired service. The process costs nearly $55,000 per year and is likely an even higher expense when city labor costs for transporting material is factored into the total. In addition, quantities of wood chips generated are not used up every year, so the wood chip volume continues to grow. The following recommendations are offered for Greenbelt’s consideration so that resources currently allocated for wood waste disposal could be directed at more proactive and productive urban forest management tasks: • Contact other nearby entities to explore opportunities to partner with or learn from their waste utilization practices. There are several local agencies near Greenbelt that are excellent resources for information and can provide information for developing a sustainable wood residue program. The following have or are investigating innovative, cost-effective wood recycling programs:

o MDNR Division of Forestry. Completed and are still conducting a variety of research projects to market excess wood and other green waste products from urban forestry maintenance operations.

o Baltimore City’s “The Camp Small Zero Waste Initiative” (http://www.treebaltimore.org/programs/camp-small).

o “Camp Small” is the wood waste collection yard run by the Baltimore City Department of Recreation and Parks. The 12-acre site is located in the Jones Falls Valley just north of Cold Spring Lane. Every day, city crews and contractors bring logs, chips, and brush to the site for processing. In early 2016, the Recreation & Parks Forestry Division, in collaboration with the Baltimore Office of Sustainability, began the Camp Small Zero Waste initiative in an effort to sort and distribute the variety of wood products at the site.

o Baltimore County Public Works Department. Conducted training sessions for public works employees to identify marketable timber and wood products; currently investigating establishing wood yards for sale of timber, firewood, and wood chips. • Explore partnerships with private businesses and recycling firms for sustainable wood waste reuse. The following companies offer reduced cost or free disposal of wood and organic waste, which can eliminate the need for green waste materials storage, tub grinding rental, and landfill fees:

o DC Materials

o Garman Brothers Lumber

o Excel Tree Service

o RELS Landscaping Supply

o Remington Mulch

o Progressive Waste Solutions

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• Explore cooperative agreements or arrangements with surrounding communities to increase wood waste utilization efficiencies. Consider sharing ideas, staff, equipment, facilities, collection contracts, and wood volumes/products with nearby communities. This may be the best way to increase the city’s ability to deal with wood and leaf residues. For instance, when combining logs from tree removal operations that are suitable for milling, a “critical (and salable) mass” can be reached to the point where it becomes cost-effective for sawmill and organic waste recycling companies to buy or at least pick up municipal products. Selling or delivering lumber quality logs to sawmills may end up being a break-even effort, but recycling urban wood is a practice that may help the city meet its sustainability goals. • Increase promotion of the use of the available wood chips locally and regionally. With greater awareness of free compost and mulch from city tree maintenance operations, the products may be in greater demand. Suggestions for marketing and increasing local use of recycled green waste are as follows:

o Explore creating an app or a feature on the city’s website where property owners can easily request delivery of wood chips and even compost. Two examples are: - FreeMulch: https://freemulch.abouttrees.com/#!/requestersignup - ChipDrop: https://www.chipdrop.in/

o Consider a requirement for developers in Greenbelt to use public mulch and compost during construction projects for temporary erosion control, tree protection, etc. They can also be encouraged to top-dress the soil with municipal compost before final seeding and landscape installations. 11. Increase Resources for Urban Forest Management Successful urban forest management requires that an experienced certified arborist with updated equipment be more readily available to perform proactive tasks described in these 12 Next Steps. Currently, the city has an arborist on staff that dedicates 50% of their time to urban forestry tasks, with remaining time is used toward other public works efforts. The list of recommendations in this plan will require more staff time than is currently available. Therefore, an increase in staff is recommended. The increase in staffing is needed to do the following: conduct annual tree health care, risk, and post-storm event inspections, conduct the annual cyclical maintenance inspections and inventory updates, inspect park and trail trees, and report findings to department heads, Advisory Committee on Trees (ACT), and council, as well as collaborate with city and external agencies to initiate projects and improve service delivery. This additional staff time can also assume and assist with administrative and public relations tasks, such as keeping the tree inventory database current, conducting outreach programs, coordinating tree steward volunteers, and assisting with grant applications.

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This can take the form of changing the existing part-time urban forestry staffer/arborist to a dedicated full-time staff position focusing on the needs dictated in this plan. Or the current position can remain, and a new, additional part-time arborist can be added to the staff to aid the current arborists’ efforts in urban forestry. • Allocate 100% of existing full-time dedicated Certified Arborist to urban forestry (estimated funding needs: $37,500), or • Hire an additional part-time city arborist on staff (estimated funding needs: $37,500), or • Hire a consultant urban forester. If hiring processes and funding for personnel are such that the city cannot accomplish these first two options, the additional arborist staff needs could be filled through a qualified urban forestry consultant on an as-needed basis. Estimate Funding Needed: Estimated 60 hours per month at $75 per hour = $4,500 per month or $54,000 per year. Additionally, there is a need for equipment upgrades, specifically the replacement of the existing aerial lift. This equipment is critical to everyday tree care and is due for replacement. No matter the choice of staff or equipment upgrades, additional resources create a structure that will result in more frequent and dedicated professional expertise on the streets, park, and other public properties in Greenbelt. 12. Develop and Implement an Outreach Plan Most of the recommendations so far have focused on changes and improvements the city can make to preserve and increase Greenbelt’s urban forest. However, as a large percentage of the tree canopy is located on private property, real long-term progress requires action by private property owners. This work should be purposefully planned and allotted funding. Engaging the wider community involves explaining the importance and benefits of green infrastructure, but also highlighting the role it plays in ensuring Greenbelt’s livability, sustainability, and support of cultural identity. Community support for the urban forest in the public realm can include tree-related advocacy groups and trusts; groups or homeowner associations that lobby for more street trees and greenery in their neighborhoods; and others who demand open space and tree protection through better planning, regulation, and public acquisition. Community groups and dedicated individuals can provide the ‘glue’ to link open space networks within larger metropolitan areas, and they can provide the political backbone to sustain public investment in green infrastructure. There are multiple ways to engage the public. Topics or messages must first be defined. Avenues of targeted communication to deliver those messages must then be determined and finally implemented.

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Messaging The public has a limited capacity for messages in today’s high-tech world. More effective communication occurs by choosing a few messages (3–5 only) and repeating them over and over. Important topics and messages that could be considered for Greenbelt include the following: • Message 1. Current Canopy and Value of Greenbelt Trees. Present the current canopy level and benefits the canopy provides. This is typically the first message to send out, as all other messages should connect back to this one. This can also be a way to “roll out” the urban forest master plan to the public (why Greenbelt needs canopy, current canopy level, and the plans to achieve those goals). Along the same lines, the value of tree canopy can be conveyed to business owners. Educating local business owners on the impact a shady commercial district can have on sales (see study referenced on page 4) can also be a method to boost the desire for increased canopy along main thoroughfares and neighborhood streets while engaging the public. Additionally, the value of mature trees could be highlighted. People often do not realize that the large tree they have is a value to their property, the community, wildlife, and the environment. Greenbelt has already taken steps to convey the value of mature trees in the community through the designation of Greenbelt’s Significant Trees program and tour (brochure). This kind of landmark or heritage tree program makes removal of those trees less likely. • Message 2: How You Can Get Involved. What are the actions the city wants people to take? Determine those actions and insert this “ask” on every outreach effort. This must be decided locally, but options include:

o Give citizens the choice to opt in for a tree. This could simply be a way to request a street tree. Alternatively, plant a tree in their own yards. o Volunteer at a tree planting event. o Join a tree care team. o Donate funds for an upcoming planting or to raise money for a tree giveaway. • Message 3: Tree Threats. Public trees are subject to demise as a result of disease infestation as well as neglect and poor care. With education, the citizens of Greenbelt can become aware of the common threats to the tree canopy and what they can do to help. The first topic in this category may be the emerald ash borer. The public will benefit from an education on what to expect, how to identify ash trees, what the city is doing about EAB on public land, and options for management on their own land. • Message 4: General Tree Care. There are a number of actions people take that are detrimental to trees at all stages of life, including improper mulching and pruning. Easy tips and tidbits of information to share with citizens are important.

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• Message 5: Update Citizens on Trees and Utilities Efforts. If the recommended 20 pears are removed each year (see Recommendation #5), consider starting with those under utility lines first. Then, to lessen public outrage at removals, plantings should be well spaced out throughout the city (not 20 in two consecutive blocks) and proactive communication initiated that this is being done as part of a larger effort for overall tree care – species diversity improvement, lessening harsh pruning by utilities, and ridding community slowly of invasive pears. • Message 6: Storm Response. This topic is only implemented after a significant storm event and focuses on helping private citizens handle storm damage and work to save trees from premature removal. Recommendation #3: Develop a Formal Risk Management Program also includes further discussion on this topic. Avenues of Communication There are numerous avenues that convey the message to citizens. • Social Media. Social media sites such as Facebook and Twitter can create buzz and promote involvement in the current urban forestry activities occurring locally. They are also not just a tool for the younger generation. In recent years, smartphones and Facebook have given social media a wider reach. • Comprehensive Plan. The overall city canopy level and efforts to promote canopy preservation should be incorporated into the next comprehensive plan. This ensures that urban forestry goals continue through the turnover common in elections and staff changes. • Presentations to City Leadership and Local Groups. Part of the roll-out of a plan involves defining audiences, partnerships, potential champions, and reaching out to the public, with the goal of encouraging the audience to learn about and join in on the work called for in this plan. This can be done through multiple presentations to varying audiences – council members, city boards/committees, business association, city staff, regional environmental groups, and others. Be sure to have an “ask” at the end of the presentation. What do you want them to do next? This work often unearths new partners and funding sources that can otherwise go untapped. • Door Hangers. In the case of the proactive notification of removals or pruning in an area (see Message 5), messaging can be distributed to nearby homes only via a door hanger that explains that the tree maintenance is part of the urban forestry master plan. • Create a Citizens’ Volunteer Tree Care Team. In every community, there is a core group of people who want to do more than just plant a tree. Give these citizens more responsibility while alleviating some of the tree establishment work performed by public works staff. Also, consider involving arborists in training and mature high school or college interns to assist citizen volunteers in outreach, new tree care, coordinating planting plans, and assisting at community outreach events.

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Partnerships should be initiated with organizations that can help promote, enhance, and preserve the UTC. Organizations can include local businesses, local utilities, regional partners, and the Advisory Committee on Trees. Other audiences to engage can include young people, businesses, landscape architect firms, regional groups, the general public, and all city staff departments. Actions that can be taken by each partner should be defined.

Volunteer Tree Care Program Examples Tree Tenders, Pittsburgh, PA. In 1993, the Pittsburgh Shade Tree Commission (PSTC) created a volunteer program named Tree Tenders® to help plant and care for existing trees. Tree Tenders® from neighborhoods were trained to care for newly planted trees. The PSTC also helped community groups organize tree care work events and maintained a small tool bank for use by volunteers. In 2006, Tree Pittsburgh, a 501(c)(3) charitable, nonprofit urban forestry organization, was established and continued the volunteer program and created a certificated Tree Tenders® program. Tree Pittsburgh requires that Tree Tenders® take an 8-hour course and learn about urban forestry practices, tree biology and health, proper planting, pruning, and maintenance. The cost of the course is $40 (scholarships are available), which includes registration, materials, light food, and instruction. Tree Tenders® participate in events organized by Tree Pittsburgh that include tree care days, pruning workshops, and tree planting. Since 2006, Tree Pittsburgh has certified over 1,300 Tree Tenders®. CommuniTree Stewards, Syracuse, NY. Funded by the City of Syracuse and Onondaga County, the CommuniTree Steward Program started in 2002 to cost-effectively plant and maintain trees by exchanging tree maintenance classes for volunteer work on public trees. The program is run by Cornell Cooperative Extension (CCE). Students enroll in the winter and begin the required CCE courses in April. Coursework includes tree biology, tree identification, soils, matching tree species to the site, tree planting, basic pruning, structural pruning, proper mulching, and watering. Students are closely monitored and instructed during forestry projects. By the end of the summer, most students need little supervision; by the fall, CommuniTree Stewards participate in large-scale, bare-root planting events. Veteran Tree Stewards, who return annually to work on tree projects and plantings, will often pair up with new Tree Stewards and will serve as instructors. CommuniTree Stewards have planted thousands of trees in the City of Syracuse and Onondaga County villages. Volunteers are also able to serve on specialty projects such as tree inventories and invasive species mapping. Veteran CommuniTree Stewards have gone on to organize their own neighborhood projects, so the program has had an impact beyond its original intended area. Combining Youth Employment Opportunities with New Tree Care in Indianapolis. Newly planted public trees in Indianapolis don't always have predetermined caretakers. For this reason, Keep Indianapolis Beautiful (the city's nonprofit tree partner) employs a team of young people to plant, mulch, stake, water, and prune public trees for seven weeks each summer. The Youth Tree Team program, which began in 2008, pays local high school students to take on this role of promoting new tree establishment and care. The program is supported through corporate donations, a foundation, and other donations.

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FUNDING True success in maintaining the urban forest depends on continuing support from the public sector, developers, businesses, and the wider community. The City of Greenbelt recognizes that a long-term funding commitment is required over the next two decades to effectively implement proactive care tactics described in this plan. Table 6 presents estimated budgets over the next five years for activities related to this plan’s recommendations and the prioritized short-term tasks.

Table 6. Budget Estimates and Recommendations for Greenbelt

GREENBELT ESTIMATED BUDGET REQUIRED (rounded figures)

Existing Task Details Year 1 Year 2 Year 3 Year 4 Year 5 Budget (for comparison) Annual Inspection $960 $960 $960 $960 $960 (City-Wide, Level 1) Yearly Assessment (1) Contractors Re-Inventory One Management Sector (Level 2) $1,280 $1,280 $1,280 $1,280 $1,280 $26,940 Routine (approx. 330 trees/year - 15-year cycle) $86,790 $86,790 $86,790 $86,790 $86,790 Cyclical Pruning (2) Priority/Safety or Storm Response Undetermined Undetermined Undetermined Undetermined Undetermined

LABOR Removals (45 trees) $40,500 $40,500 $40,500 $40,500 $40,500 Removals (3) Stump Removal (45) $6,750 $6,750 $6,750 $6,750 $6,750 Staff Program Administration (4) Management Staff $37,500 $75,000 $75,000 $75,000 $75,000 $133,500

Tree Succession (5) Planting 100 Trees per Year $11,000 $11,000 $11,000 $11,000 $11,000

Young Tree Care (6) Pruning, Watering, Mulching Young Trees $5,280 $14,000 $18,000 $22,000 $26,000

Labor Subtotal (13) $190,060 $236,280 $240,280 $244,280 $248,280 $160,440

Tree Succession (5) 100 Trees & Related Materials $20,000 $20,000 $20,000 $20,000 $20,000 $12,008

UTC Analysis (6) Current UTC Assessment and Change Analysis $0 $0 $10,000 $0 $0 $0

Ordinance Update (7) Tree Ordinance and Zoning Regulations $0 $0 $0 $0 $0 $0

Leaf and Brush Removal (8) Tub Grinder $7,466 $7,466 $7,466 $7,466 $7,466 $7,466

OTHER Equipment (9) Aerial Lift Replacement $180,000 $0 $0 $0 $0 $0 Fuel and Maintenance for Chipper, Dump Trucks, Equipment Maintenance (10) $4,860 $4,860 $4,860 $4,860 $4,860 $4,860 and Aerial Lift Tree inventory Software and GIS Licenses, Computer, and Cell $2,500 $2,500 $2,500 $2,500 $2,500 $2,500 Hardware (11) Public Outreach; Staff Training; Miscellaneous Other (12) $5,000 $5,000 $5,000 $5,000 $5,000 $565 Expenses or Projects Other Costs Subtotal (13) $219,826 $39,826 $49,826 $39,826 $39,826 $27,399

TOTAL $409,886 $276,106 $290,106 $284,106 $288,106 $187,839

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(1) Assumes approximately 24 hours in-house staff @ $40/hour for citywide inspection of streets and park trails; and 32 hours in-house staff for Level 2 assessment and re-inventory of street trees and trails (if applicable) per sector. (2) Assumes average $263/tree for 4-person, in-house staff to perform complete/ANSI standard pruning on a 15-year cycle to start (approx. 330 trees per year), with a goal of shortening the cycle over time. Without a complete inventory with tree condition data, this can only be a guess. Costs for storm response and risk reduction pruning are variable and cannot be predicted at this time. (3) Assumes 0.5% general mortality and 20 pear trees and the equal number of stumps; $150 for stump removal; 80% of the tree removal is performed by in-house staff @ an average of $500/tree; 20% of the tree removal is performed by contractors @ an average of $2,500/tree. (4) Assumes a full-time city arborist position or a part-time assistant city arborist would be hired in Year 2. Change from existing $37.5k half person to one FT person or a PT arborist assisting the implementation of the Master Plan. (5) Assumes average of $310/tree (average of reported contractual and in-house costs for tree planting). $200 per tree, $110 for labor. Past years average 80 trees planted per year; new budget assumes 100 trees per year. (6) Assumes $5,280 for watering PepCo trees in Y1, and $40/tree for contractual or in-house staff and materials for watering, fertilization, and pruning of 100 additional trees each year in Y2–Y5; the cost could be reduced for labor if completed by volunteers. (6) Assumes this would be contracted to a consultant; estimate may change depending on deliverables and breadth of analyses. (7) Assumes city staff, members of the Advisory Committee on Trees, and legal counsel would complete this task. (8) Assumes equipment for annual green debris collection (tub grinding) @$7,470. (9) Assumes replacement aerial lift is purchased in Y1. Replacement need dictated by Greenbelt staff. (10) Assumes no changes in equipment or maintenance or fuel costs; costs reported as $4,859/year. (11) Assumes $2,500 annually for current system; the purchase and adoption of a specialized/customized tree inventory data management software program will likely be the same annual cost. (12) Assumes approximately $1,000/year for staff development/training, and $4,000/year for public engagement and other small special projects. (13) All assumptions were based on financial data estimated by and provided by city staff, and from estimated tree population numbers and characteristics. The individual task costs and annual program total costs are not to be relied upon for actual budgeting purposes. When the tree inventory is complete, and more accurate accounting figures are available, then the plan budget should be revised to reflect the known, realistic costs. This budget shows a sharp jump in funds the first year, primarily due to the needed replacement of the aerial lift truck. Excluding this one-time investment, the overall budget calls for an annual fund of $280k–290k depending on the year, which is a $80k–100k increase in annual funding. However, since neither complete inventory data nor exact urban forest management program budget amounts were available, a variety of reasonable assumptions were made to estimate the annual funding levels over the next five years.

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Partnerships for Funding and Urban Forest Management Program Support Development of the urban forest is an area of public planning that the government does not need to tackle alone. Public/private partnerships can be created where mutual goals can be achieved in support of a sustainable urban forest. Developers have always looked for a marketing edge for their properties. The best developers understand that building green means not just structural design, but the entire development site and its relationship to its surroundings. Tree preservation and open space contributions are also effective ways to support and advance tree programs and other green infrastructure initiatives in newly developing areas. Business partners can be powerful contributors to the expansion and success of urban forestry through financial support, planting and maintenance of trees on commercial property, and support of civic organizations involved in forestry. Some businesses have a direct stake in urban forestry as a function of their own enterprises. Others may be interested in offsetting environmental impacts. Demonstrating Value Achieving funding stability ultimately depends on ongoing support by the public to demand that the City of Greenbelt remains committed to the program. Much of this hinges on communicating and disseminating information about the benefits of Greenbelt’s urban forest that directly impact residents’ lives with respect to reduced stormwater pollution, electricity saved, carbon and water savings from lower energy use in buildings, lower demands on power generating plants, biodiversity benefits, and temperature reductions in the city as a whole – not to mention the city’s aesthetic enhancement and wide-ranging social and economic advantages. Urban forest project and program costs can be more easily justified when they can be linked to specific benefits derived from tree planting and maintenance. The provision of a robust cost-benefit analysis for the urban forest will help ensure that it remains competitive as a high-value land use among hard infrastructure and transportation. In other words, stable support from the community is generated by a long-term track record of documenting and disseminating those benefits.

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GOING FORWARD: FIVE-YEAR PLAN This plan should be considered a “living” working document. The goals and recommendations presented should be reviewed annually, and appropriate adjustments should be made for the following year. The entire document itself should be reviewed in five years to determine if management and urban forest conditions have changed significantly. The overall five-year plan for implementing a proactive urban forest management program and addressing the issues and challenges in Greenbelt is summarized below. Benchmarks are also provided to gauge the success of efforts to improve urban forest management service delivery in the first five years. Year One The first year of implementation should focus on announcing the plan, acquiring funding and other resources, and planning work for Year Two. • Inventory update initiation • Perform routine and emergency maintenance • Plant trees in parks and on streets • Begin initial risk management activities • Begin utility coordination work • Share plan and findings with the citizens, elected officials, and community leaders • Begin process for adding additional staff • Purchase a replacement aerial lift truck • Explore customized tree inventory data management software programs Year Two Year Two is centered on completing the tree inventory by the end of the year, implementation of the first year of cyclical care plan, and expanding the capacity of city staff to implement the urban forest master plan. • Complete inventory of public trees and vacant planting sites • Select and install customized tree management software (if desired) • Begin cyclical tree maintenance • Plant trees in parks and on streets • Plan for new UTC assessment • Hire, reorganize, or otherwise assign a city staff member to be a full-time city arborist charged with implementing the plan • Explore alternatives for wood waste processing/disposal

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Benchmarks 1. Completed inventory and maintaining database. 2. Cyclical care has begun. 3. Staff complement has been expanded. 4. Citizens have been engaged through meetings, social media, the city websites, and through volunteer opportunities. Year Three Year Three is focused on determining the current UTC, starting a new/young tree care program, and continuing the cyclical maintenance program and tree planting. • Start new tree care program • Perform sector-based inventory update and required maintenance • Perform a risk assessment of street trees • Perform UTC assessment with change analysis • Ordinance review and updating Benchmarks 1. Current UTC assessment and comparative analysis are complete. 2. Draft revisions to tree ordinance and zoning code are complete. 3. Street tree risk assessment has been performed. 4. Cyclical maintenance, invasive removal, risk reduction, and planting continues. Year Four Year Four is centered on continuing the proactive tree care and planting programs and making budget, staff, equipment, and contractual services adjustments based on solid inventory and performance data from the previous three years. • Perform a budget analysis based on the current inventory and UTC data. • Continue new tree care program. • Perform sector-based inventory update and required maintenance. • Begin park tree risk assessment.

Benchmarks 1. Budget analysis and operational review have been completed. 2. Ordinance revisions have been approved and adopted. 3. Cyclical maintenance, invasive removal, risk reduction, and planting continues.

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Year Five By the end of Year Five, the cyclical management plan should be fully implemented and ongoing each year, the public tree risk assessment have been completed, and the urban forest management plan reevaluated. • Re-evaluate the urban forest management plan and adjust goals, strategies, and budget as needed or desired based on current conditions, available resources, and public input. • Cyclical maintenance, invasive removal, risk reduction, and planting continues. • Continue new tree care program. • Perform sector-based inventory update and required maintenance.

Benchmarks 1. Updated urban forest master plan is complete. 2. Cyclical maintenance, invasive removal, risk reduction, and planting continues. 3. Street and park tree risk assessments have been completed.

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CONCLUSION The management of public trees is challenging to say the least. Urban forest managers have the daunting task of balancing the recommendations of experts, the wishes of council members and other elected officials, the needs of citizens, the pressures of local economics, concerns for liability issues, the physical aspects of trees, the forces of nature and severe weather events, and the desire for all of these needs to be met all at once. How do you eat an elephant? The answer is one bite at a time. This plan recommends short- and long-term goals and objectives that Greenbelt can implement incrementally until the urban forest management program is providing the level of service desired by staff and citizens. This plan has established a clear set of priorities and objectives related to the goal of maintaining a productive, sustainable, and beneficial community forest. By implementing this master plan, the City of Greenbelt can be more effective in meeting the true needs of the trees and the community. Implementation of this plan will achieve the vision stated for Greenbelt’s trees—that they “are iconic features of this historic community, creating an urban oasis that provides a high quality of life to residents. Our goal is to maintain and expand upon this legacy, both today and for future generations.” Greenbelt and other communities will have achieved this goal of a sustainable urban forest when these “benchmarks” have been reached: ● Elected officials pass and enforce favorable ordinances protecting Greenbelt’s trees, and fully fund the urban forestry program. ● Planning departments include trees in comprehensive plans, encourage conservation easements and low-impact development, and enforce codes to protect trees. ● Public works and engineering staff value trees equally with other municipal infrastructure and include tree planting and protection on all of their projects. ● Economic and community development staff advocate trees and greenspace to increase property values, shopping revenues, attract new business investments, and understand that trees are an incentive, not an obstacle, to economic investment. ● Health departments and the medical community recognize and promote the value and benefits of trees for personal and societal health benefits. ● Citizens volunteer for tree commissions appear before local council to support trees and provide planting and maintenance labor for special projects.

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GLOSSARY Advisory Committee on Trees (ACT): A Greenbelt volunteer committee providing advice and expertise to the City Council on on matters related to the city’s tree resources. aesthetic/other report: The i-Tree Streets Aesthetic/Other Report presents the tangible and intangible benefits of trees reflected by increases in property values in dollars ($).

air quality report: The i-Tree Streets Air Quality Report quantifies the air pollutants (ozone [O3], nitrogen dioxide [NO2], sulfur dioxide [SO2], coarse particulate matter less than 10 micrometers in diameter [PM10]) deposited on tree surfaces and reduced emissions from power plants (NO2, PM10, Volatile Oxygen Compounds [VOCs], SO2) due to reduced electricity use measured in pounds (lbs.). Also reported are the potential negative effects of trees on air quality due to Biogenic Volatile Organic Compounds (BVOC) emissions. American National Standards Institute (ANSI): ANSI is a private, nonprofit organization that facilitates the standardization work of its members in the United States. ANSI’s goals are to promote and facilitate voluntary consensus standards and conformity assessment systems, and to maintain their integrity. ANSI A300: Tree care performance parameters established by ANSI that can be used to develop specifications for tree maintenance. arboriculture: The art, science, technology, and business of commercial, public, and utility tree care. canopy: Branches and foliage that make up a tree’s crown. canopy cover: As seen from above, it is the area of land surface that is covered by tree canopy.

carbon dioxide report: The i-Tree Streets Carbon Dioxide Report presents annual reductions in atmospheric CO2 due to sequestration by trees and reduced emissions from power plants due to reduced energy use in pounds. The model accounts for CO2 released as trees die and decompose and CO2 released during the care and maintenance of trees. community forest: see urban forest. condition: The general condition of each tree rated during the inventory according to the following categories adapted from the International Society of Arboriculture’s rating system: Excellent (100%), Very Good (90%), Good (80%), Fair (60%), Poor, (40%), Critical (20%), Dead (0%). cycle: Planned length of time between vegetation maintenance activities. defect: See structural defect. diameter: See tree size. diameter at breast height (DBH): See tree size. failure: In terms of tree management, failure is the breakage of stem or branches, or loss of mechanical support of the tree’s root system. further inspection: Notes that a specific tree may require an annual inspection for several years to make certain of its maintenance needs. A healthy tree obviously impacted by recent construction serves as a prime example. This tree will need annual evaluations to assess the impact of construction on its root system. Another example would be a tree with a defect requiring additional equipment for investigation. Davey Resource Group 48 November 2018

genus: A taxonomic category ranking below a family and above a species and generally consisting of a group of species exhibiting similar characteristics. In taxonomic nomenclature, the genus name is used, either alone or followed by a Latin adjective or epithet, to form the name of a species. geographic information system (GIS): A technology that is used to view and analyze data from a geographic perspective. The technology is a piece of an organization’s overall information system framework. GIS links location to information (such as people to addresses, buildings to parcels, or streets within a network) and layers that information to provide a better understanding of how it all interrelates. grow space size: Identifies the minimum width of the tree grow space for root development. inventory: See tree inventory. i-Tree Streets: i-Tree Streets is a street tree management and analysis tool that uses tree inventory data to quantify the dollar value of annual environmental and aesthetic benefits: energy conservation, air quality improvement, CO2 reduction, stormwater control, and property value increase. i-Tree Tools: State-of-the-art, peer-reviewed software suite from the USDA Forest Service that provides urban forestry analysis and benefits assessment tools. The i-Tree Tools help communities of all sizes to strengthen their urban forest management and advocacy efforts by quantifying the structure of community trees and the environmental services that trees provide. management costs: Used in i-Tree Streets, they are the expenditures associated with street tree management presented in total dollars, dollars per tree, and dollars per capita. monoculture: A population dominated by one single species or very few species. net annual benefits: Specific data field for i-Tree Streets. Village-wide benefits and costs are calculated according to category and summed. Net benefits are calculated as benefits minus costs. ordinance: See tree ordinance. overhead utilities: The presence of overhead utility lines above a tree or planting site. right-of-way (ROW): See street right-of-way. risk: Combination of the probability of an event occurring and its consequence. species: Fundamental category of taxonomic classification, ranking below a genus or subgenus, and consisting of related organisms capable of interbreeding. street right-of-way (ROW): A strip of land generally owned by a public entity over which facilities, such as highways, railroads, or power lines, are built. street tree: A street tree is defined as a tree within the right-of-way. structural defect: A feature, condition, or deformity of a tree or tree part that indicates weak structure and contributes to the likelihood of failure. sulfur dioxide (SO2): A strong-smelling, colorless gas that is formed by the combustion of fossil fuels. Sulfur oxides contribute to the problem of acid rain. Davey Resource Group 49 November 2018

summary report: A report generated by i-Tree Streets that presents the annual total of energy, stormwater, air quality, carbon dioxide, and aesthetic/other benefits. Values are reflected in dollars per tree or total dollars. tree: A tree is defined as a perennial woody plant that may grow more than 20 feet tall. Characteristically, it has one main stem, although many species may grow as multi-stemmed forms. tree benefit: An economic, environmental, or social improvement that benefits the community and results mainly from the presence of a tree. The benefit received has real or intrinsic value associated with it. tree height: If collected during the inventory, the height of the tree is estimated by the arborist and recorded in 10-foot increments. tree inventory: Comprehensive database containing information or records about individual trees typically collected by an arborist. tree ordinance: Tree ordinances are policy tools used by communities striving to attain a healthy, vigorous, and well-managed urban forest. Tree ordinances simply provide the authorization and standards for management activities. tree size: A tree’s diameter measured to the nearest inch in 1-inch size classes at 4.5 feet above ground, also known as diameter at breast height (DBH) or diameter. urban forest: All of the trees within a municipality or a community. This can include the trees along streets or rights-of-way, in parks and green spaces, in forests, and on private property. urban tree canopy (UTC) assessment: A study performed of land cover classes to gain an understanding of the tree canopy coverage, particularly as it relates to the amount of tree canopy that currently exists and the amount of tree canopy that could exist. Typically performed using aerial photographs, GIS data, or Lidar. volatile organic compounds (VOCs): Hydrocarbon compounds that exist in the ambient air and are by-products of energy used to heat and cool buildings. Volatile organic compounds contribute to the formation of smog and/or are toxic. Examples of VOCs are gasoline, alcohol, and solvents used in paints.

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REFERENCES American Lung Association (ALA). 2015. State of the Air 2015. http://www.stateoftheair.org (accessed May 30, 2015). American National Standards Institute. 2008. ANSI A300 (Part 1)–2008, American National Standard for Tree Care Operations—Tree, Shrub, and Other Woody Plant Management—Standard Practices (Pruning). Londonderry: Tree Care Industry Association, Inc. Burden, D.2008."22 Benefits of Urban Street Trees." Walkable Communities, Inc. http://www.walkable.org/assets/ downloads/22BenefitsofUrbanStreetTrees.pdf.Accessed March 2015. ———. 2011. ANSI A300 (Part 9)–2011, American National Standard for Tree Care Operations—Tree, Shrub, and Other Woody Plant Management Standard Practices (Tree Risk Assessment a. Tree Structure Assessment). Londonderry: Tree Care Industry Association, Inc. ———. 2012. ANSI A300 (Part 6)–2012, American National Standard for Tree Care Operations—Tree, Shrub, and Other Woody Plant Management Standard Practices (Transplanting). Londonderry: Tree Care Industry Association, Inc. Casey Trees. 2008. Tree Space Design: Growing the Tree Out of the Box. Washington, D.C.: Casey Trees. City of Philadelphia. 2014. City of Philadelphia Green Streets Design Manual. Philadelphia, PA: City of Philadelphia Mayor’s Office. Coder, K. D. 1996. “Identified Benefits of Community Trees and Forests.” University of Georgia Cooperative Extension Service, Forest Resources Publication FOR96-39. Cornell University Cooperative Extension. 2013. Street Tree Inventory. Village of Mamaroneck. USDA Forest Service and DEC Urban and Community Forestry. Dutchess County. 1-37. Cuyahoga River Restoration (CRR). 2015. www.cuyahogariver.org. Accessed June 1, 2015. Dolan, R.W. 2015. “Two Hundred Years of Forest Change: Effects of Urbanization on Tree Species Composition and Structure.” ISA Arboriculture & Urban Forestry. 41(3): 136-145. Greenbelt Forest Preserve. 2017. “About the Greenbelt Forest Preserve.” https://www.greenbeltforestpreserve.org/about-the-forest- preserve. Accessed June 12, 2017. Hauer, R.J. and Peterson W.D. 2016. Municipal Tree Care and Management in the United States: A 2014 Urban & Community Forestry Census of Tree Activities. Special Publication 16-1, College of Natural Resources, University of Wisconsin – Stevens Point. 71 pp. Heisler, G. M. 1986. “Energy Savings with Trees.” J. Arbor 12(5):113–125. Prepared by Ryan Bell and Jennie Wheeler. Hirabayashi S. 2014. i-Tree Canopy Air Pollutant Removal and Monetary Value Model Descriptions. http://www.itreetools.org/canopy/resources/iTree_Canopy_ Methodology.pdf. [Accessed January 6, 2017].

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Karnosky, D. F. 1979. “Dutch Elm Disease: A Review of the History, Environmental Implications, Control, and Research Needs.” Environ Cons 6(04): 311–322. Kuo, F., and W. Sullivan. 2001a. “Environment and Crime in the Inner City: Does Vegetation Reduce Crime?” Environment and Behavior 33(3): 343–367. ———. 2001b. Aggression and Violence in the Inner City - Effects of Environment via Mental Fatigue. Environment and Behavior 33(4): 543–571. Long Island Sound Study (LISS). 2015a. “Important Costal Habitat Types” http://longislandsoundstudy.net/issues-actions/habitat- quality/important-coastal-habitat-types/. Accessed March 6, 2017. Long Island Sound Study (LISS). 2015b. “What Makes Long Island Sound Special?” http://longislandsoundstudy.net/about-the- sound/what-makes-it-special/. Accessed March 6, 2017. Lovasi, G. S., J. W. Quinn, K. M. Neckerman, M. S. Perzanowski, and A. Rundle. 2008. “Children living in areas with more street trees have lower prevalence of asthma.” J. Epidemiol Community Health 62:647–9. McPherson, E. G., R.A. Rowntree. 1989. “Using structural measures to compare twenty-two U.S. street tree populations.” Landscape J. 8(1):13–23. Megalos, M. 2015. “Branching Out: The North Carolina Forest Stewardship Activity Guide.” NC Forest Stewardship State Committee and North Carolina Cooperative Extension Office, NC State University. http://content.ces.ncsu.edu/branching-out-the-north- carolina-forest-stewardship-activity-guide. Accessed November 1, 2015. Miller, R. W., and W. A. Sylvester. 1981. “An Economic Evaluation of the Pruning Cycle.” J. Arbor 7(4):109–112. North Carolina State University. 2012. “Americans are Planting Trees of Strength.” http://www.treesofstrength.org/benefits.htm. Accessed May 12, 2012. Nowak, D. J., E. J. Greenfield, R. E. Hoehn, and E. Lapoint. 2013. “Carbon storage and sequestration by trees in urban and community areas of the United States.” Environmental Pollution 178(July):229-236. doi:10.1016. Ohio Department of Natural Resources. 2012. Position Statement: Master Street Tree Planting Plans. http://ohiodnr.com/LinkClick.aspx?fileticket=uq3ki%2FMX51w%3D&tabid=5443. Accessed April 3, 2012. Pennsylvania Horticulture Society (PHS). 2015. Green Land Care Program: Evidence of Success. http://phsonline.org/programs/landcare-program/evidence-of-success. Accessed December 15, 2016.

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Pokorny, J.D., J.G. O’Brien, R.J. Hauer, G.R. Johnson, J.S. Albers, M. MacKenzie, T.T. Dunlap, and B.J. Spears. 1992. Urban Tree Risk Management: A Community Guide to Program Design and Implementation. U.S. Forest Service, Northeastern Area State and Private Forestry. NA-TP-03-03. St. Paul, MN: USDA Forest Service. Richards, N. A. 1983. “Diversity and Stability in a Street Tree Population.” Urban Ecology 7(2):159–171. Seitz, J. and F. Escobedo. 2008. “Urban Forests in Florida: Trees Control Stormwater Runoff and Improve Water Quality.” School of Forest Resources and Conservation Department, UF/IFAS Extension. https:// edis.ifas.ufl.edu/fr239. Accessed November 3, 2015. Smiley, E. T., N. Matheny, and S. Lilly. 2011. Best Management Practices: Tree Risk Assessment. Champaign: International Society of Arboriculture. Smith, D. 1999. “The Case for Greener Cities.” American Forests. Autumn 1999 v. 105 (3). Stamen, Randal. S. “Understanding and Preventing Arboriculture Lawsuits.” Presented at the Georgia Urban Forest Council Annual Meeting, Madison, Georgia, November 2–3, 2011.Ulrich, R. 1984. “View through Window May Influence Recovery from Surgery.” Science 224(4647): 420– 421. Thomas, Morton A and Associates. 2016. Forest Health Preserve Assessment. https://www.greenbeltforestpreserve.org/about-the- preserve/2016-forest-preserve-health-assessement/ Ulrich R.S., R.F. Simmons, B.D. Losito, E. Fiority, M.A. Miles and M. Zeison. 1991. “Stress Recovery During Exposure to Natural and Urban Environments.” J. Envir Psych 11(3): 201-230. University of Minnesota Extension. "Verticillium Wilt of Trees and Shrubs." http://www.extension.umn.edu/garden/yard-garden/trees- shrubs/verticillium-wilt/. Accessed March 24, 2017. USDA Forest Service. 2003a. “Benefits of Urban Trees. Urban and Community Forestry: Improving Our Quality of Life.” Forestry Report R8-FR 71. U.S. Department of Agriculture. 2011. "Baltimore-Washington Partnership for Forest Stewardship." Forest Service, Northeastern Area, State and Private Forestry. https://www.na.fs.fed.us/ss/11/baltimore--washington-partnership-stewardship.pdf Accessed June 12 2017. US DOE, Department of Energy. 2015. “Tips: Heating and Cooling” http://www.energy.gov/energysaver/tips-heating-andcooling. Accessed November 10, 2015. US DOT, FHWA. 2015. Bicycle & Pedestrian Planning: Best Practices Design Guide. https://www.fhwa.dot.gov/environment/bicycle_pedestrian/publications/sidewalk2/sidewalks209.cfm. Accessed July 10, 2015.

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EPA U.S. Environmental Protection Agency. 2015. Heat Island Effect: Trees and Vegetation. http://www.epa.gov/heatislands/mitigation/trees.htm. Accessed May 30, 2015. Wegener, A. 2014. "The Story of Brow: Planting Street Trees Beyond the Right-of-Way: and What it Means for New Yorkers." (http://nysufc.org/the-story-of-brow-planting-street-trees-beyond-the-right-of-way-and-what-it-means-for-new- yorkers/2014/05/20/). Accessed December 12, 2016. Wolf, K. L. 1998a. “Urban Nature Benefits: Psycho-Social Dimensions of People and Plants.” University of Washington, College of Forest Resources Fact Sheet. 1(November). ———. 2009. “Trees & Urban Streets: Research on Traffic Safety & Livable Communities.”http://www.naturewithin.info/urban.html. Accessed November 10, 2011. ———. 2007. “City Trees and Property Values.” Arborist News (August):34-36. ———. 2003b. Is All Your Rain Going Down the Drain? Look to Bioretainment—Trees are a Solution. Davis, CA: Center for Urban Forest Research, Pacific Southwest Research Station. ———.2003. “Public Response to the Urban Forest in Inner-City Business Districts.” J. Arbor 29(3):117–126. ———. 2000. “Community Image: Roadside Settings and Public Perceptions.” University of Washington College of Forest Resources Factsheet. 32(August). ———. 1999. “Grow for the Gold.” TreeLink Washington DNR Community Forestry Program. 14(spring). ———. 1998b. “Trees in Business Districts: Positive Effects on Consumer Behavior!” University of Washington College of Forest Resources Fact Sheet. 5(November). ———. 1986. “Human Responses to Vegetation and Landscapes.” Landscape and Urban Planning 13:29–44.

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APPENDIX A TREE RISK ASSESSMENT TERMINOLOGY Tree Risk Assessment Qualification (TRAQ) is an ISA qualification program that trains arborists how to use the methodologies outlined in the ISA Best Management Practices for Tree Risk Assessment. This qualification promotes the safety of people and property by providing a standardized and systematic process for assessing tree risk. The results of a tree risk assessment can provide tree owners and risk managers with the information to make informed decisions to enhance tree benefits, health, and longevity. It has been recommended that Greenbelt begin to incorporate the ISA Best Management Practices for Tree Risk Assessment methods and terminology into the urban forest management program. Doing so will bring the risk management aspect of Greenbelt’s program up to current arboricultural industry standards, as well as to insurance and risk management industry standards. The following briefly explains the risk assessment best management practice and terminology used in TRAQ, and recommended for Greenbelt: 1. Risk Assessment Process—During a risk assessment, post-storm inspection, or whenever a risk assessment is required, each tree is assigned a risk rating. The failure mode (i.e., branch, whole tree, codominant stem) with the greatest risk serves as the overall tree risk rating. The specified time period for the risk assessment is typically one year. Ratings are determined by the following criteria: • Likelihood of Failure. Identifies the most probable failure and rates the likelihood that structural defect(s) will result in failure based on observed current conditions. • Likelihood of Impacting a Target. The rate of occupancy of targets within the target zone and any factors that could affect the failed tree as it falls toward the target. • Categorizing Likelihood of Tree Failure Impacting a Target. The likelihood of failure and the likelihood of target impact are combined in the matrix below to determine the likelihood of tree failure impacting a target.

Likelihood of Impacting Target

Likelihood of Failure Very Low Low Medium High Imminent Unlikely Somewhat likely Likely Very likely Probable Unlikely Unlikely Somewhat likely Likely Possible Unlikely Unlikely Unlikely Somewhat likely Improbable Unlikely Unlikely Unlikely Unlikely

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• Consequence of Failure. The consequences of tree failure are based on the level of target and potential harm that may occur. Consequences can vary depending upon the size of defect, distance of fall for the tree or limb, and any other factors that may protect a target from harm. Target values are subjective, but efforts will be made to assess them from the client’s perspective. 2. Risk Rating—The tree’s risk rating is determined based on combining the likelihood of tree failure impacting a target and the consequence of failure in the matrix below.

Consequences Likelihood of Failure Negligible Minor Significant Severe Very likely Low Moderate High Extreme Likely Low Moderate High High Somewhat likely Low Low Moderate Moderate Unlikely Low Low Low Low

Using this system of tree risk assessment, Greenbelt can be more proactive in managing risk and can establish a threshold for risk. To use this assessment protocol effectively, at least one staff member should become TRAQ qualified and/or a TRAQ qualified consulting forester should perform the risk assessments.

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APPENDIX B TREE RISK ZONE CATEGORIES FOR PUBLIC TREES Tree Risk Zones Categories for Public Trees Risk Zone Examples Category 1. Emergency access routes 2. Medical and emergency facilities and shelters, handicap access areas 3. Police, fire, and other public safety facilities 4. School playgrounds Very High 5. Individual trees or neighborhoods with very high-risk tree characteristics such as: • Standing dead trees, or those with poor condition class ratings • Severely storm-damaged trees • Trees visually obstructing traffic signs, stop lights, or security lights • Tree roots causing severe sidewalk buckling 1. Main thoroughfares 2. High-use parks, playgrounds, and picnic areas 3. Parking lots adjacent to high-use public areas 4. Bus stops along high-use roads High 5. Paved, high-use trails 6. Individual trees or neighborhoods with very high-risk tree characteristics such as: • Overmature trees • Severely storm-damaged trees • High density of large-diameter, mature, or “problem” tree species • Root injury caused by sidewalk or road construction 1. Secondary roadways 2. Neighborhoods with a moderate density of large-diameter, mature, or “problem” tree Moderate species 3. Moderate use parks, playgrounds, and picnic areas 4. Undeveloped trails 5. Parking lots adjacent to moderate-use areas 1. Low-use roads and public areas with dispersed recreation Low 2. Open areas, woods, riparian corridors 3. Neighborhoods with a low density of large-diameter, mature, or “problem” tree species

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Suggested Minimum Guidelines for Inspection Methods and Schedules for Greenbelt Based on Risk Category and Zone Risk Categories for Street Timing of Suggested Inspection Method and Park Areas/Zones Inspections Walk-by; Very High Annual Individual Tree Inspections Walk-by; High 1–2 years Individual Tree Inspections Walk-by; Moderate 3–5 years Individual Tree Inspections Walk-by; Individual Tree Inspections Low 5–7 years or Drive-by; Windshield Surveys Drive-by; All Areas After severe storms Windshield Surveys

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APPENDIX C EXAMPLES OF TREE RISK MANAGEMENT GOALS The two guiding principles of tree risk management are increasing public safety and promoting tree health and sustainability. However, there is little point to establishing tree risk management policies and procedures unless goals are set and there is a practical way of determining whether progress is being made towards achieving those goals. Suggested goals and metrics for Greenbelt are as follows: • Comprehensive Goal. Greenbelt’s urban forest will be healthy and will not threaten the welfare of the residents and visitors. Long-Range Goals o Annual tree removals will fall below 1% of the total tree population. o Annual priority pruning needs will fall below 5% of the total tree population. All public trees will have a risk level no higher than Moderate. Short-Range Goals o The city will complete a public tree inventory by Year 2. o The city will complete a street tree risk survey by Year 3. o The city will complete a park tree risk survey by Year 5. o A systematic inspection of the city’s street trees to identify and mitigate potential tree related risks will be completed on a regularly scheduled basis by Year 5.

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APPENDIX D TREE MANAGEMENT SOFTWARE OPTIONS

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Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

APPENDIX E TREE EMERGENCY PLAN WORKSHEET

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

Davey Resource Group November 2018

APPENDIX F CANOPY BENEFIT METHODOLOGY i-Tree Landscape (https://landscape.itreetools.org) is a tool developed jointed by the U.S. Forest Service and Davey Tree, that allows free regional analyses of tree benefits for cities, counties, and more. Land cover classification for an area is first determined using the National Land Cover Database (NLCD). Then based on these results, i-Tree Landscape calculates the ecosystem services/benefits that tree canopy provides. Three benefits areas are examined – carbon, air pollution, and stormwater interception. Methodology on each follows. Carbon. Carbon storage and annual sequestration values are calculated from two separate sources depending upon location in non- forest or forest land cover. Non-forest carbon: For non-forest NLCD classes, total carbon storage and net annual sequestration were estimated using values from urban forests (Nowak et al., 2013). Net annual sequestration is estimates of carbon accumulation from tree growth minus estimated carbon lost through decomposition due to tree mortality. Carbon storage was estimated based on the national average storage value of 7.69 kgC/m2 tree cover (standard error (SE) = 1.36 kgC/m2). Net sequestration was based on state estimates that varied based on length of growing season and averaged 0.226 kgC m2 tree cover/yr (SE = 0.045 kgC m2 tree cover/yr). State values varied from 0.430 kgC m2 tree cover/yr (Hawaii) to 0.135 kgC m2 tree cover/yr (Wyoming) (Nowak and Greenfield 2010). These estimates per unit of tree cover are essential as these values were applied to the tree cover estimates (m2) from the tree cover map to estimate total carbon (kg). Forest carbon: For forested regions, total carbon storage and net annual sequestration were derived from U.S. Forest Service Forest Inventory and Analysis (FIA) data for each county (special thanks to Jim Smith for extracting these county FIA data). Net annual sequestration was carbon accumulated annually between FIA re-measurements based on accumulation from tree growth and new trees minus carbon lost through tree mortality. Note: sequestration in forests is based on field measurements of change including the influx of new trees and loss of existing trees; in non-forest areas, net sequestration is modeled based on tree growth of existing trees and estimated mortality based on tree condition over a one-year period; this estimate does not include new tree influx and only includes a partial loss of carbon from mortality due to decomposition (entire carbon from trees is not removed, only part of carbon lost to decomposition is removed). Total carbon storage and net sequestration per hectare of land was converted to total carbon storage and net sequestration per hectare of tree cover by dividing the carbon per hectare by percent tree cover in the forest land in the county. As tree cover on FIA land was not known, tree cover estimates from NLCD forest classes were used. In counties where tree cover in forest land was less than 10% (19 counties), tree cover was set to 10% to avoid inflating carbon density values per unit of cover due to low tree cover estimates. If a county had no FIA carbon storage data, but had tree cover estimates, storage density values (kgC/m2 tree cover) from the closest county were used. FIA carbon storage densities per m2 of land area averaged 6.3 kgC/m2; carbon storage density adjusted for tree cover equaled 9.8 kgC/m2 tree cover. Davey Resource Group November 2018

Net sequestration per m2 of tree cover was calculated in the same manner as for carbon storage. For net carbon sequestration, values for some counties are missing. If a county had a missing value, sequestration density values (kgC/m2 tree cover/yr) from nearby counties in the same state were used. If the entire state had missing values, the county sequestration value was estimated based on converting the national FIA sequestration density value from all known counties to state values based on the ratio of state sequestration densities to national sequestration density for non-forest areas: Forest sequestration density for state = national average forest density x (state non-forest sequestration density / national average non- forest density). This procedure was used for net forest sequestration in many western states (AZ, CA, ID, MT, NM, NV, OR, UT, WA, WY). The average net sequestration value for forests was 0.14 kgC/m2 tree cover/yr (average SE = 0.10 kgC/m2 tree cover/yr)(see "i-Tree Landscape Carbon Storage and Sequestration for U.S. Counties"). This value is about 60% of the non-forest sequestration value. This difference is likely due to increased growth rates in urban areas (due to more open-grown nature of trees) and differences in means of calculating net sequestration (forest estimates remove all carbon from trees that die, but in urban estimates only a small portion are removed). Value of carbon storage and sequestration is estimated at $139.33/metric ton of carbon (Interagency Working Group 2013). Air Pollution. Air pollution removal and value estimates are based on procedures detailed in Nowak et al. (2014). This process used local tree cover, leaf area index, percent evergreen, weather, pollution, and population data to estimate pollution removal (g/m2 tree cover) and values ($/m2 tree cover) in urban and rural areas for each county. These values are applied to the m2 of tree cover to determine total removal and values related to carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), particulate matter less than 2.5 microns (PM2.5), particulate matter between 2.5 and 10 microns (PM10*), and sulfur dioxide (SO2). Value estimates are based on local health impacts estimated using the U.S. EPA BenMAP model for each county (based on local population data) for all pollutants except for CO and PM10*, which use externality values ($/t) to estimate pollutant removal value. Estimates of pollution removal varied by county. Average county removal rates are used but have a potential maximum and minimum value (see i-Tree Landscape Pollutant Ranges) that illustrates a potential range. The minimum and maximum values on average are about 57% of the mean value. Average differences from the mean varied from a low of 30% for NO2 to a high of 106% for PM2.5. The maximum and minimum values are likely unreasonable values as they assume a maximum or minimum removal rate for every hour of the year. No maximum or minimum values are estimated for CO. Hydrology. Estimates of avoided runoff for each county in the conterminous United States in 2010 were developed using the i-Tree Eco model and local leaf area indices and weather data. Methods are detailed in Hirabayashi (2015), Hirabayashi and Endreny (2015), and Hirabayashi and Nowak (2015). The margin of error on these estimates is unknown. Further methodology can be referenced on the i-Tree Landscape web site: https://landscape.itreetools.org/references/.

Davey Resource Group November 2018