Delaware County’s Office of Sustainability on Wednesday presented a countywide tree‑canopy assessment that finds about 43% of the county is currently covered by trees and that the county experienced a net canopy decline of roughly 2% between 2010 and 2022.

The assessment, commissioned under the county’s 2023 sustainability plan and paid for with a Commonwealth Financing Authority grant, used high‑resolution LiDAR, aerial imagery and land‑cover analysis performed by consultants (the University of Vermont and Save a Tree Consulting Group) to map existing canopy, vegetation that could become canopy, impervious surfaces that might be converted, and areas unsuitable for new canopy. The consultants provided data at four scales: hexagon grid, municipality, census tract and census block group.

The study reports about 117,000 acres in the county, of which roughly 43% (about 50,000 acres) was classified as existing tree canopy. Consultants estimated about 4,200 acres of canopy gain and about 7,000 acres of canopy loss across the time period, producing an overall net decline of roughly 2% — about 2,000 acres — countywide. The analysis also identified more than 1.6 million individual trees in the canopy layer and found most wooded patches are small (generally less than one acre), which has implications for biodiversity and habitat connectivity.

County staff described the methods used: LiDAR flight data to establish three‑dimensional canopy signatures, aerial imagery for visual verification, and automated tree‑centroid detection to identify individual trees. The presenter said the report supplies both absolute and relative change metrics and that change can reflect both loss or gain of whole trees and growth or shrinkage of canopies over time. Staff noted the consultants supplied multiple data formats so municipalities, environmental advisory councils and tree commissions can conduct their own local analyses.

The presentation included visual examples: a residential property where trees were removed to install a pool and a portion of the Cardinal O’Hara campus where a stand of trees was cleared for building expansion. Staff emphasized that the report does not include tree species inventories or formal tree‑health assessments; those would require localized field surveys.

Speakers at the meeting asked about data availability and next steps. County GIS staff served as project manager for the data delivery and county staff said the full report is posted on the Office of Sustainability website and that additional map layers and shapefiles are available on request. Staff identified potential next steps: municipal profile maps, targeted plantings, partnering with local nonprofits for plantings, and follow‑up work to assess species and health at a local scale.

Why it matters: the report offers a more detailed baseline than prior national datasets (staff said the county‑level LiDAR work is substantially higher resolution than typical 30‑meter national datasets) and is intended to help the county and its municipalities prioritize where plantings or protections could have the greatest ecological and equity benefits.

The Office of Sustainability encouraged environmental advisory councils, tree commissions and municipal staff to request the data relevant to their jurisdiction and to use the study as a starting point for local planting and preservation initiatives.