**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** OVER EIGHTY PERCENT OF THE US POPULATION NOW LIVES IN CITIES, AND BY 2050 THAT NUMBER IS EXPECTED TO GROW TO ALMOST 90%. THUS, ECOSYSTEM SERVICE PROVISIONING WITHIN URBAN AREAS IS INCREASINGLY IMPORTANT FOR THE HEALTH AND WELLBEING OF US CITIZENS. URBAN DEVELOPMENT HAS OUTPACED KNOWLEDGE OF HOW TO OPTIMIZE URBAN ECOSYSTEM FUNCTION FOR COMMUNITIES, BUT, EVEN IN THE FACE OF THIS KNOWLEDGE GAP, SCIENTISTS AND URBANPRACTITIONERS AGREE THAT URBAN TREES PROVIDE IRREPLICABLE SERVICES TO RESIDENTS; THEY PROMOTE HUMAN HAPPINESS, MITIGATE THE IMPACTS OF HEATWAVES, CLEAN THE AIR, AND REDUCE THE INCIDENCE OF AND MORTALITY FROM HUMAN CARDIOVASCULAR AND LUNG DISEASE. THE CONTINUATION OF THESE SERVICES INTO THE NEXT CENTURY RELIES ON THE ESTABLISHMENT, GROWTH, AND FUNCTIONING OF MATURE AND NEWLY-PLANTED TREES. UNFORTUNATELY, GLOBAL CLIMATE WARMING MAY INDUCE HEAT AND WATER STRESS THAT THREATENS TREE HEALTH AND PERFORMANCE. HOWEVER, SPECIFIC EFFECTS OF CLIMATE CHANGE ON ECOSYSTEM SERVICES PROVIDED BYTREES ARE POORLY MEASURED AND UNDERSTOOD, IN LARGE PART BECAUSE WE LACK EXPERIMENTAL TECHNIQUES FOR MANIPULATING CLIMATIC CONDITIONS EXPERIENCED BY TREES AT THE CITY SCALE. IN THIS PROJECT, WE ADDRESS THIS KNOWLEDGE GAP BY MEASURING TREE RINGS ACROSS URBAN HEAT GRADIENTS (HOTTER AND COOLER MICROREGIONS) IN THREE CITIES WHERE TREES RECEIVE DIFFERENT AMOUNTS OF PRECIPITATION: SACRAMENTO, RALEIGH, AND NEW ORLEANS. THIS STUDY WILL DIRECTLY MEASURE TREE RESPONSES TO URBAN HEAT, CLIMATE CHANGE, AND PRECIPITATION TO IMPROVE TREE SPECIES SELECTION. TO DETERMINE HOW TO BEST INTEGRATE OUR RESULTS INTO TREE SPECIES SELECTION AT THE CITY LEVEL, WE WILL APPLY SOCIAL SCIENCE APPROACHES TO DETERMINE HOW SPECIES SELECTION DECISIONS ARE CURRENTLY MADE.