How Are Trees Doing 5 Years After Development? A Tree Steward Project.

We are all dismayed to see so many trees removed when an old house is torn down and a new one built. Yes, Arlington County has regulations requiring preservation and replanting, yet we wonder if these are sufficiently followed? This summer six Tree Stewards conducted a pilot project of 32 such sites under the direction of Urban Forester Vincent Verweij to determine the answer to this question. The pilot project was so useful, so we plan on repeating it soon.

Yep, that river birch is on plot and they added an extra Magnolia!

The volunteer work was fun and instructive. First, we learned how to read the intricate site plans required at each development so we could tell how many trees should have been conserved, and how many new plantings should have been installed on what spot in the property.  Then in pairs we went to that address, knocked on the door, and asked if we could count their trees. Sometimes the homeowner welcomed us, proudly showing off their beautiful trees conserved, planted during development and those they’ve added over the five years! Some were skeptical and refused admittance to the property, and many were not home leaving us to determine how many trees existed on the property from public sidewalks. We must have looked strange to neighbors, wearing our yellow TS vests, standing on tip toe to see over fences, and making notes on clipboard!

The pilot project process will be improved for the next time:

  • More TS will be recruited and trained for the next survey to be scheduled soon
  • The reporting sheet has been revised for clearer definitions  
  • An initial letter on TS letterhead describing the project will be sent to all homeowners
  • information on TS and tree maintenance will be left with each homeowner

The results show good news in that 233 trees have been planted in the last 5 years; however, the unhappy news is that only 46 of the 83 originally conserved old trees on site still survived after 5 years.

A more thorough description of the project and the results are as follows:

In 2018, 320 private properties were developed in Arlington County.  The Chesapeake Bay Preservation Ordinance requires a Landscape Conservation Plan for any site disturbance greater than 2,500 sq. ft.  Department of Parks and Recreation forestry staff reviews and enforces the requirements of the Landscape Conservation Plan.  Residential properties must demonstrate how the site will have 20% forest canopy in twenty years. This can be achieved by using existing trees or trees proposed for planting. 

For each of the 320 properties, a site plan was required by the County which showed 1) the trees to be removed due to construction, 2) the trees to remain after construction (conserved trees), and 3) any trees that need to be planted to provide the 20% canopy density after twenty years (planted trees)if the credit for conserving existing trees is not sufficient.  Note that this requirement only applies to the development of the property, and legal restrictions to removal of trees after the completion of the development may be limited.

An Anonymous plan sample. Tree Stewards worked from larger originals comparing the plan to the current yard.

A tree survey was conducted in 2023 to ascertain the effectiveness of the 2018 Landscape Conservation Plan.  This allowed for five years between site development and the present, which provides information on long-term trends in compliance with the Preservation Ordinance. Ten percent of properties developed in 2018 (32) were randomly selected, and pairs of Arlington County Tree Stewards approached property owners and asked permission to delineate the trees currently on the property.  Of the 32 properties visited, 4 were not able to be surveyed because either permission was not granted, or nobody was home on multiple visits and the property could not be assessed from the road.  

The results of the survey show that 55% of the conserved trees (i.e., trees present which were to remain according to the site plan) were still present in 2023 (46 of 83 trees), and 86% of the trees that were required to be planted were present in 2023 (117 of 136 required trees). In addition, 163 additional trees were planted; however, many of these were not canopy trees (arbor vitae, crepe myrtle, etc.).  In addition, 11% of the properties had more conserved trees than were on the plan (i.e., not all trees slated to be removed were cut down) 14% of the properties had more trees planted than were required in the site plan (an additional 163 trees were planted).

Photos for this blog post were provided by Steve Geiger and Nora Palmatier

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Tree of Heaven: How to Address this Sadly Misnamed Plant

Despite its serene name, Ailanthus altissima, more commonly known as Tree of Heaven, is less than a gift from above. A non-native invasive originating in China, Tree of Heaven spreads rapidly, outpacing native plants in its growth and often killing them through chemical secretions in the soil. They also serve as a prime host for another harmful invasive species, the spotted lanternfly. 

Unfortunately, mitigating the spread of this plant is not as simple as just cutting down the trees you see. Learn how you can do your part to slow the spread of this pernicious pest.

  1. Identifying Tree of Heaven

Tree of Heaven has several distinctive features. It has bark described as resembling cantaloupe, with long compound leaves that have two distinctive “bumps” or “notches” at the base. The leaves have a distinctive rancid peanut or cat urine-like smell. 

This time of year (late summer to fall) Tree of Heaven is very distinctive, with the female tree sporting peach/salmon/coral colored seeds in clusters.  

If you see any mature female trees on public land, particularly in Arlington and Alexandria, please identify them using the iNaturalist application. This will allow local government officials and researchers to track the spread of these trees. When submitting photos of the trees, please submit photos that show the seed clusters, as well as another photo or two that show the characteristic leaves and bark of the tree to ensure accurate tree ID.

  1. Managing Tree of Heaven

As unintuitive as it may seem, cutting down tree of heaven ends up creating a Hydra-like issue: it triggers resprouting from the roots and the stump of the tree, leading to multiple trees taking the place of the original tree.

Only trained staff or contractors should be removing tree of heaven (or any trees!) from public land. For those aiming to mitigate tree of heaven on their private property, you can follow the below steps:

  • If the tree is still just a seedling/very small sapling that has NOT produced seeds, you can pull the tree out, ensuring all roots are removed. It’s a bit easier to do this after it has rained when the soil is looser.
  • If the tree is producing seeds and/or is relatively well-established, apply a targeted herbicide, being careful to not apply it to surrounding plants. The two recommended options are:
    • Basal bark method: Apply a solution of a 20-25% concentration of oil-soluble triclopyr ester product in an oil-based carrier is highly effective. Using a handheld or backpack sprayer, apply the mixture in a continuous 12-inch wide band around the tree base. The basal bark method requires no cutting and is generally used for trees that are less than six inches in diameter, though larger stems (up to 16 inches) may also be treated effectively
    • Stem injection (hack-and-squirt) method: This technique is very effective when applied during the summer. It requires first making downward-angled cuts into the sapwood around the tree trunk at a comfortable height, using a hand ax. With a spray bottle or wand, squirt the selected product into the cuts within a minute or two, so that the bottom of the cut is covered but the liquid doesn’t run out. This method can be used with trees of any size, though it is most effective with stems over two inches in diameter. A triclopyr product is most often recommended.
  • Once the tree has died, then you can safely remove it. 
  1. Be on the Lookout for the Spotted Lanternfly

Tree of Heaven is a key host for the spotted lanternfly. Eggs are laid in late fall and can be found on any flat surface such as trailers, logging equipment, and on tree bark. They hatch as “nymphs” in mid-April and become adults in July. 

Clockwise from top left: Adult showing hind wings, adult with folded wings, early black and white nymphs, full-grown nymphs showing red, and egg masses.

If you see any spotted lanternflies, please kill nymphs/adults as able, then report the sighting and location with either a photo of the insect or the sample itself to your local Virginia Cooperative Extensive office.

For more information on Tree of Heaven, consult the Virginia Department of Forestry’s article on Ailanthus Control Methods and their Guide for Virginia Landowners on the Control and Utilization of Tree-of-Heaven. For more information on spotted lanternflies, consult the Virginia Cooperative Extension’s resources on Spotted Lanternfly in Virginia.

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Applications Closed – Becoming a Tree Steward!

Applications for the Fall 2023 Training class are now closed. Thank you so much for your interest! If you are interested in participating in future training classes, please email us at We will notify you via email when we plan to host the next class.


Applications were accepted through July 24th for Fall 2023 Training Class.  Forty spaces were available.

This will be a hybrid training of weekly live Zoom presentations on Tuesday evenings and assigned readings. Additionally, there will be five required in-person weekend sessions with experienced Tree Stewards and tree care professionals. 

The list of topics will include: tree physiology, tree identification, soils, urban tree problems, invasive trees and plants, forest ecology, right tree right place, tree selection and sourcing, tree planting, and tree pruning.

A preliminary schedule of classes will be announced in early August.  Classes will begin with an in-person meeting at Lubber Run Amphitheater on Saturday, September 9.  Classes will finish in early-to-mid November, with an in-person graduation gathering in early December.

Questions? Please feel free to email us.

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Tree Planting With Marymount University

On Saturday, March 25, 2023, 15 Marymount University students and staff braved a steady rain to join 10 Tree Stewards and two Arlington County urban foresters in planting 25 native trees in Arlington’s Tyrol Hill Park

This project was the result of a heat mapping study that Marymount University students did a year ago, in which the Tyrol Park area off of Carlin Springs Road/Columbia Pike was identified as one of the hottest parts of the county, with low tree canopy to boot.  The Marymount students then raised the funds and worked with Arlington County Urban Forest Manager Vincent Verweij to design a planting that, over time, will help cool the area.

The photos show some of our muddy and exhilarated crew at the end of the session.  This planting was made harder by the rain, but the trees had no complaint, and now that these high-quality Casey Tree Farm trees are leafed out, it is clear that the effort was well worth it!

Photos provided by Tree Steward volunteers.

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2022 Review: Almost 10,000 Trees Assisted

The Tree Stewards of Arlington and Alexandria were certainly busy in 2022. Our 92 members provided over 4,000 hours of service in the region. In particular, we provided education to around 5,200 people, and provided maintenance to nearly 10,000 trees.

The Tree Stewards participated in a diverse range of activities.

The greatest number of hours volunteered is in our parks, in particular working with our partners in Arlington County and the City of Alexandria to provide hands-on tree care on public property.

Our volunteers also spend a lot of time on public education, in particular ensuring the public understands the importance of our native canopy. We do this through information tables at community events, by hosting tree walks, or hosting virtual presentations.

We also work closely with the Arlington Tree Canopy Fund and consult with homeowners to select the right tree for their yard. This past year we were privileged to work with EcoAction’s Tree Equity Program to successfully reach previously underserved communities.

Tree Stewards of Arlington and Alexandria welcomes all citizens who care about trees to join us. For information on training classes, upcoming activities, requesting a Tree Steward speaker, or to comment on trees in your neighborhood, email:

The data in this post comes from TrackItForward, our volunteer hour reporting platform. It consists of self-reported data, submitted by Tree Stewards. It was turned into data visualizations by Tree Steward Emily Potosky.

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Native Trees Planted Through Partnership With Community and One Tree Planted

On Sunday October 23rd, 2022, community members joined 9 Tree Stewards in Alexandria Virginia’s Ben Brenman Park to plant 28 native trees.

A photo showing volunteers posing with their newly-planted tree.

The tree species planted included White Oak, Sweet Gum, Eastern Red Cedar, Common Hackberry, Black Locust, Sycamore, and Black Gum.

A photo showing volunteers removing a tree from its container

This planting was made possible by a generous grant from One Tree Planted which covered the cost of the trees and supplies, including twenty-eight 5- to 7-gallon container trees, mulch, stakes, watering bags and trunk protectors.

A photo showing volunteers spreading mulch around a tree
Photos showing volunteers planning where to plant the tree

Newly-planted trees need regular watering to thrive, and the importance of follow-on watering was not ignored. The City of Alexandria generously offered to include the newly planted trees on its watering contract for the 2023 growing season.

This was a learning opportunity for the volunteers, who showed great interest in Tree Stewards coaching how to properly plant trees to get the trees off to a great start and a long life.

A photo showing volunteers taking turns digging a hole for the tree
Photos showing volunteers with volunteer shirts

Photos provided by Tree Stewards of Arlington and Alexandria.

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Tree Stewards Partner with TD Bank and the Arbor Day Foundation to Plant Native Trees

On Monday, October 17 2022, twenty-five TD Bank employees, two community volunteers, and nine Tree Stewards gathered in Alexandria’s James Marx All Veterans Park to plant 32 native trees.

A photo showing the thirty-six participants.

The trees were species like Sweet Gum, Northern Red Oak, Black Locust, Common Hackberry, and White Oak.

A photo showing a volunteer driving a tree-supporting stake into the ground.

This planting was made possible by a generous grant from TD Bank through the Arbor Day Foundation, which covered the cost of trees and materials to ensure they thrive. These specifically included thirty-two 5- and 7-gallon container trees, mulch, stakes, watering bags, trunk protectors, and funding for watering for the growing season (May-September 2023).

A photo showing two volunteers with their newly-planted tree.

The volunteers showed great interest in Tree Steward coaching on proper tree planting, including details of how to carefully detangle circling roots and get the trees off to a great start and a long life.

A Tree Steward demonstrates how to properly plant a tree.
A photo showing a TD Bank volunteer and a Tree Steward posing with their newly planted tree.

Thanks so much to our partners TD Bank and the Arbor Day Foundation for making this tree planting event a success!

The TD Tree Days logo
The Arbor Day Foundation logo

Photos provided by TD Bank.

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Tree Stewards Do i-Tree Canopy Measurement from their Desks

By Nora Palmatier, President

Ever since Tree Stewards’ first tree census project at Ft. Myers Joint Base in 2008, members have completed similar tasks for the Tree Canopy Fund, and in neighborhood parks, schools, churches, and condos. Each project, we kept our feet on the ground, looking up into the trees’ canopy, and recording information with pencil and paper.

This summer, our tree measuring projects were literally turned upside down and we looked down on the tree leaves using Google Earth imagery through i-Tree Canopy. This is a free software tool from the United States Forestry Service that can be used on personal computers to easily and accurately estimate tree and other cover classes (e.g., grass, building, roads, etc.) within a set area. Urban Forest Manager Vincent Verweij used his GIS skills to set up our citizen science project using the boundaries of Arlington County, Virginia (including National Airport and all Department of Defense properties, which affects comparison with past canopy studies). The program is used to estimate results of tree canopy coverage – i.e., how much tree shade is there. Suddenly, we were measuring trees by looking down on the canopy instead of upwards!

Seven Tree Stewards worked on the project, and all together we looked at 6,399 views covering  Arlington County. i-Tree Canopy randomly generates sample point views and places a crosshairs marker in the middle of the view. After looking where the crosshairs fell in each scene presented, we clicked on whether it landed on: a) Tree Canopy, b) Pervious grass and vegetation, c) Impervious building rooftop or pavement of roads, sidewalks, parking lot, e) bare soil, or f) water. Each of us did close to 1,000 views.

Above is an example of what we Citizen Scientists saw, minus the crosshairs indicator.  The program provided a screen shot with the target point shown, and we clicked on whether the area beneath it is impermeable (red dots on roof and parking lots in lower left corner), tree canopy (green dots along Four Mile Run), or water (blue dot in middle of stream – on larger view water is obvious).

Among my 1,000 views where the crosshairs landed were: on top of an airplane on a runway, the roofs of houses, offices, and apartment buildings, trees, golf courses, and cemeteries (which had many gorgeous trees but a lot more herbaceous cover between graves, so where specifically the crosshairs fell determined the cover I listed). All science projects tell us to beware of operator bias, so I tried very hard to distinguish between tops of trees and shade on ground and not let my bias overcome the purpose – but it was so difficult when I identified Lacey Woods Picnic pavilion rooftop under the crosshairs so had to mark it Impermeable even though it was surrounded by a forest!

Above is the image of all 6,399 points throughout the county. Even when enlarged, it won’t clearly show the lowest canopy areas along major transportation lines as the 2016 aerial study does. 

The program report gives us much to consider. Our study estimated that the dollar value of carbon sequestered in county trees is $1,292,714, and that reduced air pollution benefit is $1,798,460 – all this besides providing beauty and shade on hot days. Statistically, having 6,399 points analyzed for a county land mass of 27 square miles is very solid, but it was sampling rather than review of the entire county land.

Comparing the results from our i-Tree Canopy points with previous studies is the proverbial apples and oranges, while comparing studies that exclude DOD and airport is like comparing apples, oranges and puppy dogs. They are all wonderful but not interchangeable. The 2022 i-Tree Canopy reported Tree Canopy at 35% compared to the 2016 aerial study of 38%. Impervious surface in 2022 was 40% and in 2016 was 38%. There was no difference between the two reports in grass and vegetation at 23% and bare soil at 1%. (Numbers for both reports are rounded and do not include sampling error estimates.)  The 2016 aerial estimate of 41% canopy coverage did not include the Pentagon parking lot or airport runways while 2022 does, so they shouldn’t be compared.

The 2022 study is county wide and doesn’t provide guidance on where tree canopy has been lost since 2016. It doesn’t provide data to determine: How much tree canopy decrease occurred on DOD land such as the National Cemetery when 700 trees were replaced with columbariums for cremated remains? How much decrease of tree canopy is due to lot clearance on private property when small houses are replaced with large ones? Was percent of increase in impervious surfaces due to new pavement or landing strips as compared to housing? Is there room in parks to plant more trees? We await the next aerial canopy study to be able to see where loss is happening and how best to manage our urban forest. Arlington County is funded to perform another study after the adoption of the Forestry and Natural Resources Plan.

Land Cover classification2022 iTree points by Tree Steward volunteers2016 study including DOD and Airport
Tree Canopy35%38%
Impervious surface (building & pavement)40%38%
Pervious grass & vegetation23%23%
Bare soil1%1%

What our i-Tree Canopy study seems to say is that Arlington County tree canopy is definitely not increasing, and it’s most likely decreasing. Our Tree Steward mission to educate the public on the importance and care of trees is even more vital as we know it is on private property that trees can be preserved and more plantings occur. We are already working to decrease canopy loss through planting efforts with the Tree Canopy Fund, tree distributions, and plantings on park land. And we provide public encouragement to plant more trees on private property as well as how to maintain mature trees. We Tree Stewards do a lot, yet this study is a call to increase our efforts; fortunately, we know that is a labor of love.

Additional information you might wish to review

TS work at Ft Myers:

TS census of Tree Canopy Fund:

About Arlington’s tree canopy

Tree removal National Cemetery

Tree Canopy Fund will plant trees for homeowners:

Free Tree Distribution:

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2022 Trainee Graduation and Membership Meeting

On April 2, TSAA celebrated the graduation of our 2022 class of Trainees! These new “Interns” have to report 30 volunteer hours in their first year to become full Tree Stewards and earn our signature green polo shirts and nametags.

Over 55 Tree Stewards and Trainees were present at this event in Lacey Woods Park.

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Tree Stewards Prune Trees in Mosaic Park, Arlington

On Monday, February 21, 2022, Tree Stewards of Arlington and Alexandria spent time pruning trees in Arlington’s Mosaic Park. By correcting structural defects in young trees, Tree Stewards expect the trees to grow up strong and healthy to shade Mosaic Park in Ballston.

Along Quincy Street in Ballston
Tree Stewards Marilyn Stone, Hugh Robinson and Dean Amel work on a willow oak.
Tree Stewards use a pole pruner on a tree near Mosaic Park’s climbing wall.

Photos by Tree Steward Jo Allen.

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