For Immediate Release May 9, 2022

To align itself with current best practices and establish a rigorous baseline from which to measure canopy change, Alexandria Urban Forestry partnered with the Spatial Analysis Laboratory at the University of Vermont to run a canopy assessment using established procedures developed in conjunction with the USDA Forest Service. This approach has been used by Seattle, New York City and Chicago nationally and Fairfax County regionally.

Canopy cover is measured in a canopy cover assessment. Assessments can measure urban tree canopy using various methods each with corresponding degrees of accuracy. Most approaches involve aerial imagery or imagery and LiDAR. The quality and accuracy of canopy assessments varies widely based on the methodology and data employed. It is up to each manager to determine what level of accuracy is required before a canopy assessment in considered defensible and actionable.  

Alexandria’s tree canopy increased to 32.5% in 2018 according to a new tree canopy assessment conducted by the University of Vermont Spatial Analysis Laboratory. The report noted a 22.4% increase from 2014 data, with the caveat that some of that canopy gain was likely spread out over a longer period than the four-year timeframe indicated. The analysis concluded that while Alexandria is losing significant canopy to human driven and natural causes, those losses are being offset by new plantings and incremental growth on existing trees. As we pursue our Citywide goal of 40% tree canopy cover by 2035, the assessment highlights the importance of preserving existing trees while continuing to plant new trees to offset losses.

For additional information and to review the assessment, visit Tree Canopy Assessment.