By Mark Eaton | [email protected]
Alexandria’s tree canopy – the branch and leaf cover provided by the city’s trees – is more than a pleasant esthetic feature. Trees cool urban heat islands, reduce stormwater runoff, clean the air and provide wildlife habitat. In an era of climate change and extreme weather events, the tree canopy has become an important city infrastructure asset.
With the city designated as a Tree City USA by the Arbor Day Foundation in 1985, its tree canopy is an important part of Alexandria’s composition. The maintenance and expansion of the tree canopy involves more than occasional tree trimming. It requires a combination of planning, resources and a full complement of qualified forestry professionals to thrive.
Managing the public portion of the tree canopy
Every tree in the city is part of the tree canopy. The approximately 30,000 trees on city property are the responsibility of the Department of Recreation, Parks and Cultural Activities. About 21% of the tree canopy is in public rights of way and another 9% is on government land. Residential property, about 1,500 acres, makes up 49% of the tree canopy. Jim Spengler and Jack Browand, RPCA’s director and deputy director, respectively, manage the public portion of the tree canopy.
RPCA’s target is to increase the tree canopy coverage to 40% of the city’s 15.7 square miles by 2035.
“We have an overall canopy goal of 40% – that’s the policy set by City Council so that’s our ultimate standard. Everything is built around trying incrementally to get there,” Spengler said.
According to a Feb. 28 Tree Canopy Assessment prepared by the University of Vermont Spatial Analysis Laboratory, Alexandria’s canopy coverage increased to 32.5% as of 2018. The study identified a net increase in tree canopy, but not in all areas of the city. Construction and wetland restoration resulted in localized declines in tree canopy.
Tree diversity and native species
Tree diversity and native species Tree diversity, in species and age, is essential to canopy health.
“The city is at risk if we have too great a percentage of one species because pest or blight can wipe everything out, as Dutch elm disease did,” Spengler said. “We’re ‘A’ in terms of variety overall, although if we start looking at sectors of the city there are issues because there are some monocultures,” or areas with dominant species.
Variety in tree ages also matters.
“You want a variety of ages – if all you have is old trees – higher risk; if all you have is young trees – higher risk,” Spengler said.
Browand said that what are considered “native” trees changes over time.
“That’s where [it] is hard for some of the homeowners – they are used to a specific [tree] being around and there is a desire to replace a tree exactly [as it was],” he said. “Our landscape guidelines will list a variety of trees that are considered native to the area.”
Some areas of the city have developments with a predominance of Bradford pear trees. “Two-thirds of our storm damage comes from those areas because the trees are weak,” Spengler said. While climate change is a factor in the selection of species for planting, Spengler said, so is variety.
“What drives what we do is more variety, types of species that have adapted to this area and are hardy and [trees] that are going to withstand the street tree environment – the plowing, chemicals that are used to treat roadways, dogs, urban density.”
Maintenance and expansion challenges
According to Browand, maintaining the city’s canopy coverage is a top priority.
“We want to maintain our canopy coverage. We have street trees that should never have been planted. If a tree goes down, our presumption is that we will replace the tree,” he said.
Some Alexandria tree wells, the space around the trunk of a tree often covered in mulch, are also designed as stormwater management systems that take water off impervious surfaces which requires trees that are hardy and can filter water.
Residents can “opt-in” or request the planting of a city tree. Different species make very different contributions to the canopy: a mature willow oak provides eight times the canopy coverage of a mature redbud tree. Browand said that RPCA is willing to discuss tree choice, but that it is “not necessarily seeking out a resident’s recommendation as to what tree should be there.”
Browand said RPCA seeks to respond to most tree-related service requests within 60 to 90 days. But tree planting takes much longer.
“I will admit, right now, there is a major backlog we are working through and it was the result of a variety of factors – part of it was the Covid issue,” Browand said.
Tree planting moves more slowly because the planting season is from approximately October to May, subject to weather conditions. Depending on where a request falls in the tree planting cycle, and the number of pending requests, it may take nine months to a year for a replacement tree to be planted.
According to a local expert, between 500 and 550 trees were planted in the 2021-2022 planting cycle. Davey Tree, the city’s contractor, is expected to plant about 650 trees in this year’s planting cycle. Spengler said the city bids out tree work approximately every three years. Davey Tree has had the contract for normal and emergency tree work and tree planting for six years.
Spengler said that the RPCA is about to contract with another company, Brightview Landscaping Services, for an inspecting arborist.
“Our constraint in the system is that we get all these work requests from citizens and we [issue] a larger number of work orders to Davey Tree but in the middle of that is inspection,” he said.
RPCA’s urban foresters can inspect a limited number of trees each day. The inspecting arborist is intended to help verify work that has been done and work that needs to be done. The highest concentration of service requests come from the oldest neighborhoods in the city.
Excluding staff salaries, the city spends $1.2 million in contracting costs, planting materials, etc. for the tree canopy.
“The public generally does not understand what a public tree is, and, secondly, what we can do or not do with private trees,” Spengler said.
A leaning or dying tree in a private yard is not RPCA’s responsibility. Nor does RPCA get involved with decisions to plant or take down trees on private property. A tree in the strip between the sidewalk and the curb is also not automatically an RPCA responsibility. For example, the general health of the trees in the Carlyle development are the responsibility of the Carlyle Community Council.
Utilities, particularly Do minion Energy, also affect the tree canopy. “[They have] license to do whatever they need to protect their infrastructure,” Browand said, “That’s why we have these V-shaped trees. They are not looking at esthetics in any way.”
Spengler said that for a healthy city tree in the area between the sidewalk and the curb, other than watering, “there is not much [a resident] can do to help other than watering and watching the tree and letting us know if a problem arises” with low-hanging branches, etc.
Alexandria hired its first city arborist in 1959. The term “arborist” has evolved to “urban forester.” RPCA staff includes three primary tree caregivers, an urban forestry manager and two urban foresters.
The urban forestry manager, formerly the city arborist position, has been vacant since May when the incumbent resigned to take a position in Arlington County. The position has been advertised and Browand said that it is expected to be filled in the near future.
One of the city’s two urban foresters resigned in late October and accepted a position with the District of Columbia. Accordingly, RPCA’s urban forester cadre is significantly understaffed.
According to Vincent Verweij, the urban forest manager for the Arlington County Department of Parks and Natural Resources, his department employs one urban forest manager and four urban foresters.
Duties of the urban forester
Scott Graham is currently the city’s only urban forester. According to Graham, “the urban forester is kind of looking at the bigger picture – the entirety of the urban forest.”
Graham developed his love of the outdoors as an Eagle Scout and then later in paramedic school. An Arlington native, Graham started as an urban forester in Alexandria last May.
His biggest challenge is managing the number of daily requests and interactions that are part of his job. According to Spengler, RPCA receives an average of about 300 requests per month for tree service.
“We’re trying to increase our canopy coverage and we’ve got a lot of forces working against that,” Graham said. “We have diseases that have come in – Dutch elm, emerald ash borer. Asian longhorn beetle is starting to get entrenched in the United States. I believe that all of our neighboring jurisdictions, except Arlington County, have spotted lantern fly.”
Graham said that an urban forester is “kind of a jack of all trades.”
“You come in with your plans and you have your standard service requests but, any day a surprise or two or three can pop up and change the direction [of the day],” he said.
Graham described the conditions when he will involve Davey Tree, the city’s tree contractor. “As a lone forester you’re only capable of so much – sometimes it’s the size of the tree that comes down, sometimes it’s the weather or extenuating circumstances.”
Often the police department will be the first responder and will assess whether a forester is needed. Graham travels with everything from clippers to chain saws in his truck.
When Graham is in the field he usually enjoys engaging with residents.
“One thing I’ve learned from this job is the passion people have for trees,” he said. “There’s a desire to understand more but there’s a love [that residents have] of their tree.”
How to hug the tree canopy
Dedicated tree-huggers can directly support the tree canopy by joining Tree Stewards of Arlington and Alexandria, a nonprofit organization that seeks to enhance a sustainable urban forest through training, volunteer activities and public education. For more information, visit https://treestewards. org/.
The tree canopy can also be supported through tax deductible contributions to RPCA’s Living Landscape Fund which received $118,772 in donations – of which $27,420 was for tree planting and maintenance – over the past five years for beautification projects which can be general or targeted to conditions in specific parks or public areas. More information is available at https://www.alexandriava.gov/PARKnerships.
RPCA also maintains a Community Matching Fund which matches contributions from for specific projects. Since its inception in 2016 the Community Matching Fund has provided $211,152 in projects to upgrade athletic fields, plant community gardens, beautify parks, expand community composting, develop a teen center, renovate playgrounds and expand outdoor exercise opportunities for seniors. The beautification projects included tree plantings.
The city’s tree canopy is a significant infrastructure asset that is easy to overlook or take for granted. As with any infrastructure component, it requires knowledgeable maintenance, careful planning and appropriate staffing to thrive.