Reforestation strategies to expand the urban forest in a legacy city

As global temperatures continue to rise, much of this heat is concentrated in urban areas due to concentrations of impervious surfaces in cities, which absorb and re-radiate heat. Urban forests provide opportunities to beautify cities as well as mitigate the harmful impacts of urban heat islands, excess stormwater runoff, climate change, and atmospheric pollution. Throughout the Midwest and Mid-Atlantic regions of the United States, legacy cities contain hundreds to thousands of vacant land parcels and urban parks which offer opportunities to expand urban forests. Parks may present opportune spaces for tree planting in cities, as residents living near vacant lots may be uncomfortable with dense tree plantings adjacent to their homes due to risks of branches falling onto property. We have implemented tree plantings across 20 municipal parks located in Dayton, OH and administered the following irrigation treatments from May through September 2024: no irrigation after planting (control), five gallons of water per tree every other week with no more than one inch of rainfall between scheduled waterings, five gallons of water per tree once per month with no more than one inch of rainfall between scheduled waterings, and 20 gallons of water per tree administered by filling a 20-gallon gator bag once per month regardless of rainfall. We tracked tree survival, growth, and health in response to these irrigation treatments to determine establishment success of native trees in urban areas. Our results will inform necessary tree aftercare practices for urban trees in the face of rising temperatures and drought.