New data suggest county’s tree-canopy level is trending higher
Arlington's tree canopy may be on a slight upswing, according to county officials.
But that doesn't necessarily mean there are more trees in the community.
A newly-released, taxpayer-funded analysis conducted for the county government by Davey Resource Group based on conditions in 2023 determined a tree-canopy rate of 35.2%. That's up from earlier studies in 2014 (32%) and 2018 (33%).
But the growth is not necessarily due to additional trees being planted to offset losses elsewhere.
"Primarily it came from expansion of existing canopy," said Vincent Verweij, the county government's urban-forestry manager.
In other words, "the tree canopy has been expanding because of the growth of trees," said Arlington County Board member Takis Karantonis.
They were speaking Wednesday (Nov. 13) at a work session where the figures were released. County staff next will take the data to the Forestry and Natural Resources Commission, and a community meeting to parse the figures is slated for Dec. 12.
Increases in overall tree canopy were reported both on private land and public lands. The new data details findings down to increments of one acre — and at a little over 26 square miles, Arlington has about 16,700 of them.
The survey also looks at canopy by civic association , with tree-canopy figures ranging from 8% (Foxcroft Heights) to 70% (Arlingwood).
Given the variety of ways figures are presented in the report, "you can so clearly see what's happening," Board Chair Libby Garvey said of trends.
The consultant says its analysis, which used aerial imaging and the laser-based measuring tool LiDAR, has a 99.2% accuracy level. Previous surveys, Verweij said, were at 95%.
The survey did not look at how many trees are contained within Arlington's 26 square miles. But in past years the guesstimate has been about 750,000, or three trees for every resident.
Arlington leaders have set a goal of maintaining a minimum 40% tree canopy, part of a regional effort being led by the Metropolitan Washington Council of Governments (COG) that launched earlier this year.
COG is attempting to reverse a downward trend. In 2023, an estimated 49.6 percent of the region's 2.2 million acres of land was covered by tree canopy, down from 51.3 percent coverage in 2014 owing in part to development throughout the region and the infrastructure that accompanies it.
The regional organization is are working to arrest the decline and maintain a 50% tree canopy going forward. More urban areas like Arlington would not be expected to hit that figure, but any increase in the inner suburbs would help the overall target .
County Board member Matt de Ferranti said the new data could be use to help guide Arlington's "strategic investments" in the upcoming fiscal 2026 budget cycle.
At this point, however, "you're not going to see a specific recommendation from me on what comes next," County Manager Mark Schwartz said.
The new survey takes into account three major federal facilities in Arlington — the Pentagon, Arlington National Cemetery and Reagan National Airport — that impact the countywide percentage.
While the 640-acre cemetery has tree cover estimated at somewhere between 30% and 40%, both the 860-acre airport and the 245-acre Defense Department headquarters have minimal tree canopy.
("They do have a little courtyard," Verweij said of the Pentagon, trying to find a silver lining.)
The survey commissioned by the county government is somewhat at odds with a study paid for by local activists . Released in 2023 and based on imaging from 2021, its consultant reported that trees covered 33% of county land, excluding the Pentagon and National Airport. Had those two facilities been included, the overall figure would have been lower.
That study concluded that tree canopy had dropped eight percentage points in just six years.
Mary Glass, a director of Arlington Tree Connection and an advocate who often has gone toe-to-toe with county officials on tree issues, was not sold on the new report, nor on government behavior.
"While the new county tree-canopy study claims the highest statistical quality, it fails to reflect the reality that our citizens are experiencing," she said.
"For many, development means clearcut lots, large and small, that change the character and value of their neighborhoods," Glass told ARLnow. "Further, it compromises the survival of their adjacent trees, floods their properties, and cancels the many health services provided by an established, mature tree canopy."
Rather than doing a victory lap, "the Board needs to reflect these realities in the strategic decisions they make on policies and budget priorities," Glass said.
There was at least some agreement from the County Board dais.
Board member Maureen Coffey said that while the overall figure is important, local leaders also needed to set "realistic sub-goals" to improve canopy where possible in specific areas of the community.
