Urban trees provide numerous ecosystem services (ESs) regardless of whether they grow on public or private lands. However, municipal tree protection policies have historically targeted public, city-owned trees while often neglecting trees on private property, which frequently comprise more than half of the urban forest canopy. Using the City of Edmonton, Canada, as a case study, this study demonstrates the necessity of protecting trees on private property in high-latitude winter cities based on the ESs they provide. We integrated tree characteristics derived from Light Detection and Ranging (LiDAR) data with the i-Tree Eco model to evaluate three primary ESs: gross carbon sequestration, avoided runoff, and air pollution removal. Results showed that private trees account for 60% of the tree canopy and provide significantly higher aggregate ESs and monetary value (p < 0.05) than public trees across mature neighborhoods. While public city-owned trees served as high-quality individual assets–characterized by larger diameters at breast height (DBH) and a higher proportion of deciduous trees–privately owned trees function as large-scale high-capacity collective assets, delivering 1.66 times greater total ESs due to their abundance. Given their substantial ecological contributions, monetary value, inherent growth constraints, and their vulnerability to infill development, urban trees in mature neighborhoods in high-latitude cities require an effective management strategy. Municipal policy frameworks in high-latitude winter cities should integrate top-down tree-protection bylaws with bottom-up community stewardship initiatives to safeguard forest canopy across both public and private lands.