Assessing the ecobenefits of a single tree at Urban HeatIsland (UHI) hotspots in major U.S. cities

Urban Heat-Island (UHI) hotspots concentrate heat risk and may offer outsized returns from strategic greening. This study evaluates the eco-benefits of planting a single street tree at the maximum UHI hotspot in 20 U.S. cities. Hotspots are identified using a composite UHI index and per-tree services are estimated for their eco-benefits. Results show relatively uniform UHI levels across cities (mean 12 F) but large variability in co-benefits. Hydrological services vary most (stormwater interception spanning an order of magnitude), and energy savings separate along climate lines: hot-summer cities are cooling-dominated (higher electricity savings), whereas colder cities are heating-dominated (greater therm savings, sometimes offsetting cooling gains in warm regions). CO reduction and pollutant removal track interception, and total monetary benefits range widely from a few hundred to several thousand dollars per tree. Multivariate analyses group cities into high-benefit coastal hubs, temperate cooling-dominant sites, and warm-climate locations with winter penalties. Overall, targeted tree planting at UHI hotspots consistently mitigates heat, but realized hydrologic, energy, and carbon returns are strongly place dependent.