Barking Up the Trees

Bark tells a lot about a tree. It is key to identifying deciduous trees in winter, when most have lost their leaves and buds may be out of reach or sight. Naturalist Michael Wojtech advocates learning bark as a means of learning trees with the goal of becoming a native with the surrounding woods.

Mockernut hickory bark

Michael Wojtech notes the diamond pattern in bark of a mature Mockernut hickory (Carya tomentosa).

He wrote the book on bark, and last Saturday (March 10), he illustrated the dozens of variations in bark in both slides and a walk with about three dozen tree lovers at the National Arboretum in the District. Casey Trees, the D.C. tree-planting non-profit, invited volunteers and others from the area to experience Wojtech’s straighforward method.

Examine the bark at eye-level. Try not to look up for other clues, such as branching habit or remaining seeds or leaves. Consider where the tree is growing: wet, dry, uphill or lower. Think about the tree’s age: young, mature, old. And then match the patterns you see with about a dozen patterns typical of trees in our area and further northeast. Touch the bark. Is it smooth, tight, peeling, rough, furrowed, scaly, or pocked with lenticels?

Bark with furrows and ridges

Touching bark gives an added sense of its nature, in this case furrows and heavy ridges.

All are clues to the species of tree, though when a young or mature tree gets up in years, its bark can change radically. An exercise with photographs of 10 younger trees and photos of them later in life stumped all but three of the groups trying to match them up. As with most worthwhile endeavors, identifying trees by their bark takes lots of practice. So, go to your favorite trees. Get to know them. Give them a gentle pat. You’ll be rewarded with knowledge.

White ash branches and samaras

It’s hard not to look up, especially when the samaras of a White ash (Fraxinus americana) are hanging on.


Michael Wojtech’s book, which contains a handy key to identify bark and dozens of photos of bark at various ages, is Bark: A Field Guide to Trees of the Northeast. His website is





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Forestry Webinars to Watch

It may be sunny outside, but the light shines brightly from your home computer if you tune in to hear or participate in urban forestry webinars that are offered free. Most, if not all, are archived about a week after their live date, so you can watch and listen at your leisure and clock those Continuing Education hours on Track It Forward.

Logo of Southern Regional Extension Forestry's Webinar Series: Understanding Urban and Community Forests
The first of a year-long series by Southern Regional Extension Forestry starts at 1 p.m. today (Wednesday, March 14). The topic is Nature and Health in Communities: A Review of Best Available Science. Later this year, our own Nora Palmatier will participate in discussing Tree Stewards: Case Study of Two Virginia Urban Tree Volunteer Programs. For more about the webinar series, which is designed for extension agents and personnel but valuable for Tree Stewards too, click here.

If you ever wondered if size matters when selecting a tree to plant, check out this most recently archived of Can simple production or propagation decisions impact landscape performance of container-grown trees? What are the returns on your investment in the size of planting stock? Will the “little dogs” catch the “big ones” in the end? In this webinar, Dr. Michael Arnold of Texas A&M University will consider the big impacts of small planting stock selection decisions. Some of the findings might surprise you.

Tree Stewards are not confused about the term “urban forestry,” but just to clear up any misunderstandings, let popular Tree Stewards lecturer Dr. Jim McGlone explain in a webinar produced for Virginia Master Naturalists and available to all at noon Thursday, March 22. Details.



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It’s Invasive Species Week

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Arlington Tree Canopy Study

As much as Arlington values its trees, the county is challenged by its increasing population and the development that this brings. Areas in red on the map have lost tree canopy since 2011, largely as the result of infill development, according to a study conducted for the county by Davey Trees.


Find the Current Urban Tree Canopy Analysis here.

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A New Threat to Fruit and Other Trees

Spotted lanternfly image. Bug has double wings.Local urban foresters and naturalists are concerned about reports that a bug that can damage grapevines as well as fruit and other trees has been found in Winchester, Virginia.

The spotted lanternfly (Lycorma delicatula) was detected in Frederick County on Jan. 10,  according to Virginia Tech and the state and federal agriculture departments. The bug, a native of China, India and Southeast Asia, was found in Pennsylvania in 2010. Last year, it jumped from six counties in Pennsylvania to 13 counties and also has been found in Delaware and New York, officials said.

In Winchester, both numerous adults and egg mass were found, according to the Northern Virginia Daily. In addition, it was found at another site approximately 400 yards away. Virginia Tech Prof. Douglas Pfeiffer, who had been searching for signs of the bug, said owners of the site were cutting down and burning all Tree of Heaven (Ailanthus alsimmia), the bug’s favorite host plant for breeding.

Tree of Heaven itself is an invasive plant that flourishes in urban areas, even in sidewalk cracks when it can get a foothold. It has spindly trunks and large compound leaves. It was introduced as a fast-growing shade tree for urban areas and was at home in the novel A Tree Grows in Brooklyn, where it was a metaphor for the tenacity of recent immigrants living near it. Despite that celebrity, it needs to be removed, preferably when  young, because it out-competes native plants that provide nourishment for the local ecosystem. Read more about Tree of Heaven here.

Pfeiffer said that even with the destruction of the host Tree of Heaven, it is likely that the spotted lanternfly already has spread from the Winchester sites. Since it is potentially a very serious pest of grapes, peaches, hops, and a variety of other crops, looking for it and reporting any finds is important. The double-winged bug damages vines and trees it infests by feeding on sap in the host plants.

The spotted lanternfly “may not have a high impact on urban areas, where orchards and large fruit tree groves tend to be less common,” Arlington Urban Forest Manager Vincent Verweij said in an email Monday.  “Nevertheless, if you believe you have found evidence of this pest, please let our state forestry department (and us) know, so we can all be aware of the pest’s extent.”

Several trees found locally could be endangered by the spotted lanternfly, according to the U.S. Department of Agriculture. They include oaks, sycamore, walnut, willow, maple, pine and poplar. The USDA site, featuring several photos of the spotted lanternfly, with its wings folded and looking like a stinkbug with a spotted back, can be found here.

Alonso Abugattas, Arlington’s natural resources manager, said on his Capital Naturalist blog: “As this is an Early Detection Rapid Response invasive, please report any sightings so we can get rid of it before it gets established locally.”

Here are links for reporting sightings to the following:

Arlington Urban Forest Manager Vincent Verweij:

Arlington Natural Resources Manager Alonso Abugattas:

Alexandria Arborist John Noelle:

Alexandria Natural Resources Manager Rod Simmons:

Falls Church Arborist Katherine Reich:

Virginia Department of Forestry’s Urban Forest Conservationist Jim McGlone:

Virginia Cooperative Extension:










Read more here.

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Arlington’s Tree Canopy Fund Survey

These trees planted in 2009 are now taller than the apartment building!

In 2008, the Arlington County Board created the Tree Canopy Fund (TCF) to ensure funds contributed by developers who cannot meet tree planting requirements on their sites will be used to plant trees on other private property.  Since then, 1,686 saplings have been planted throughout Arlington under the oversight of the Urban Forestry Commission (UFC).  The program is managed by Arlingtonians for a Clean Environment (ACE) and trees are planted by a professional tree care contractor. TCF provides larger trees planted by professionals (these root balls weigh 300 – 500 pounds, and trees are 6 feet tall!), sizes more appealing to condos, apartment managers and homeowners seeking immediate impact for the front yard and sidewalks.  Since planting larger trees professionally is more costly than providing tree whips, TreeStewards were asked to conduct a tree survey in the summer of 2017 to determine the program’s effectiveness.

Over 25 Tree Stewards along with some Master Naturalists were instructed on how to score trees on the survey sheets and told not to enter private property without permission. They were assigned neighborhoods and fanned out over the entire county to search for and assess the trees planted during the last 8 years. Volunteers also distributed educational information to homeowners on how to remove ivy from trees, correct mulching and other topics.  In many cases, volunteers rang doorbells or left notes offering to discuss tree care or ask permission to enter a backyard to better rate a tree.  Other volunteers entered the data collected and assisted with the final analysis.

A recent sweetgum planting is inspected by TreeSteward Bill.

Arlington Oaks received an oak.

  • 1,372 trees or 81.3% were found by the survey volunteers. A tree that was “not found” could mean the tree could not be observed and rated because of a fenced yard or the tree location listed was not clear.  What we do know is that less than 19% of trees planted through the TCF program have died.
  • 88% of the trees found were rated in “Good” condition. This shows that most residents who have received planted trees under the program take care of their trees. Trees were planted throughout Arlington at single family homes (49%), multifamily properties (49%), and nonprofits (2%).

The Tree Canopy Fund also funds education efforts. The 2012 community education campaign to remove ivy from trees allowed Tree Stewards and Master Naturalists to hire a professional communications firm that has resulted in more than 22,000 internet visits and 5,000 pieces of printed material distributed.  In 2018, a community campaign encouraging preservation of mature trees will be conducted by Tree Stewards. Materials will be developed by the same professional communications firm and tested on Arlington homeowners focus groups in February with campaign starting in late March.

All of the Tree Canopy Fund programs depend on volunteers for their success. Arlington residents learn about the free tree offers from notices in civic association newsletters and other media, yet it is committed volunteers who go door to door encouraging neighbors and apartment managers to apply for trees that have had the best success.  Education on tree care in the community is promoted by Arlington’s active volunteers.

The  young trees planted so far under the Tree Canopy Fund programs will require decades before they can replace the tree canopy lost by the removal of large trees during development, yet it is a start.

TreeStewards select saplings for the spring 2018 planting to ensure quality trees.

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