Quantifying natural enemy activity along a heat gradient in a legacy city

As global temperatures continue to rise, warming is exacerbated 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. However, urban trees are frequently stressed due to high heat and long periods of drought, leaving trees vulnerable to pest insect outbreaks. 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. In Dayton, OH, parks are surrounded by varying levels of impervious surfaces, leading some parks to feel hotter than others. In 2024, we implemented tree plantings across 20 municipal parks located in Dayton, OH surrounded by a gradient of imperviousness. Throughout the growing season, we provided the trees with varying levels of irrigation investments and measured tree survival, growth, and health in response to irrigation and surrounding heat. Our findings illustrate the impacts of heat and irrigation on tree health, and ongoing studies will determine how arthropod communities in these tree plantings are impacted by heat.