Winchester Tree Canopy Assessment

Winchester, a charming suburban town just outside the Boston metropolitan area, blends historic charm and tree-lined streets to create a peaceful and picturesque New England community. Winchester has been recognized as a Tree City USA member for 13 years, which highlights the community’s dedication to preserving its trees and natural surroundings. In 2024, under the direction of the Winchester Tree Committee aided by a grant from the Town and the Select Board, a tree canopy assessment was conducted to enhance understanding of the Town’s green infrastructure. This assessment evaluated the current state of the urban tree canopy (UTC) and its changes over time. The results provide a comprehensive overview of the current state of the urban forest and its future possibilities, which can be viewed in TreePlotter CANOPY.

Using 2023 aerial imagery from the USDA’s National Agriculture Imagery Program (NAIP), this study provides an near-current view of land cover in Winchester. The imagery, collected during peak growing season, making it possible to accurately identify tree canopy, grass, shrubs, soil, impervious surfaces, and water. The images were analyzed using machine learning techniques to classify land cover and manual verification to refine results. This approach reduces human bias, improves accuracy, and makes it easier to track changes in tree canopy over time.

Overall Change in Canopy

Urban forests may grow constantly as existing trees mature and new ones are planted. However, their expansion is offset by challenges such as natural disasters, pest infestations, diseases, and urban development. While it’s difficult to assess the net effect from the ground, high-resolution 60-cm aerial imagery provides a precise analysis of these canopy changes.

The study showed that Winchester’s tree canopy expanded by 53 acres between 2012 and 2018. However, from 2018 to 2023, there was a decline of 143 acres. Throughout the study period from 2012 to 2023, Winchester experienced a net loss of 90 acres of tree coverage, representing a 2.3% decrease in the urban tree canopy. This net loss is equivalent to roughly 68 football fields.