Tree Canopy Study Shows Modest Gains

Published on November 13, 2024

A new, high-accuracy study of 2023 tree canopy data, and analysis of 2018 and 2014 data, reveals a steady increase in Arlington’s tree canopy, with work remaining to reestablish and maintain at least 40% tree canopy Countywide. The latest report shows that Arlington’s tree coverage in 2023 was 35.2%, up from 31.7% in 2014 and 33.3% in 2018. Despite some tree losses, this number has been offset by continued growth of Arlington’s mature trees along with contributions from new plantings.

This report was guided by the Forestry and Natural Resources Plan, adopted by the County Board in 2023, which recommends monitoring changes in tree canopy every 3-5 years. The benefits of tree canopy include improved air and water quality, reduced impacts from urban heat, environmental and economic benefits, and positive impacts to public health and well-being.

Improved Methodology, Accuracy, and Data Quality

The Department of Parks and Recreation (DPR) worked with the nationally recognized Davey Resource Group (DRG) to conduct the survey and analysis. DRG used Light Detection and Ranging (LiDAR) technology, which provides high-resolution aerial imagery with height data to provide Arlington with the most accurate and detailed analysis so far. LiDAR technology improves data quality because it analyzes elevation which helps interpret shadows that could overcount tree coverage. 2023 data was collected and analyzed with 99.2% accuracy-- an increase from previous studies, which had an accuracy of 95%.

DRG also analyzed 2014 and 2018 data collected using the same analysis methods as the 2023 analysis to allow for comparison within this and future studies.

2023 Report Findings

Over the study periods, public land has shown a 4% increase, private land has increased by 3.7% and right-of-way areas grew by 3.2%. The largest contributor to tree canopy growth is the shift of grass and other vegetation to tree canopy. Notably, parks across Arlington County saw a 6% rise in tree canopy, growing from 59% to 65%, partly driven by the expansion of existing trees, including recent plantings.

Primary contributors to tree decline in certain areas were due to natural causes, significant storm damage during recent events, pests and diseases, development, and private tree removal decisions. DPR and their partners will use this data to identify neighborhoods most impacted by tree canopy loss, or those with low tree canopy for additional planting and conservation programs.

Explore a new Tree Canopy Statistics Dashboard with data for 2023, 2018, and 2014 by Arlington neighborhoods.

A Collective Effort Towards Tree Canopy Goals

County residents can improve tree canopy by taking steps to conserve and plant trees on their properties or within their communities. Programs such as the Tree Canopy Fund and the bi-annual Tree Giveaway offer free native trees for planting on private property. Community members with space on public right-of-way next to their homes can also request a tree planting through Arlington’s Service Request Portal. Homeowners and organizations can seek advice from private certified arborists and volunteering opportunities are also available throughout the year to help promote conservation efforts.

Virtual Information Session on Dec. 12

Have more questions? Join the Department of Parks and Recreation for a virtual community meeting on Dec. 12, 2024, from 6:30 p.m. – 8 p.m. Staff will provide an overview of the study and findings along with an opportunity to answer questions from participants. RSVP here to submit your questions and receive more information.

Learn more about the 2023 Tree Canopy Study, ways to get involved, and Arlington’s ongoing efforts towards future growth on the Tree Canopy Study webpage.