Reno, Nev. – With rising temperatures breaking records in Las Vegas and the broader southern Nevada region, a recent study sheds light on the role urban street trees could play in mitigating extreme heat. The study was published on June 17 in Environmental Research: Climate by researchers Juan Henao and John Mejia from the Desert Research Institute (DRI).
The research utilized advanced computer simulations to analyze how street trees affect local temperatures. Findings revealed that trees can create shaded areas nearly 30 degrees Fahrenheit cooler than their surroundings. Additionally, planting drought-tolerant tree species could reduce citywide nighttime air temperatures by about 3 degrees Fahrenheit.
“Trees can really improve our thermal comfort, because when we go under a tree, we can feel the difference,” stated Juan Henao, a Postdoctoral Researcher at DRI. He emphasized that factors beyond temperature, such as solar radiation reduction, also contribute to this comfort.
Given Las Vegas' desert location where native trees are uncommon away from natural waterways, identifying water-efficient tree species is crucial for cooling efforts. The study’s simulations provide insights into how different species might perform under local conditions.
While other cities have seen more significant cooling from tree transpiration — the process by which trees release water vapor — this effect is limited in Las Vegas due to dry air causing many trees to close their stomata to conserve water.
“I think there is some consensus...that in hot, arid climates, shade is the most important benefit of trees,” noted Henao. “Whereas in other regions, the transpiration is a very important factor as well.”
The study highlighted that Cherry trees offer greater cooling benefits compared to Bur Oak but require significantly more water for this effect.
Urban planning strategies should prioritize locations like sidewalks and bus stops for tree planting based on these findings. However, John Mejia cautioned that “urban trees are not a silver bullet” and mentioned ongoing research into other heat mitigation strategies like reflective materials and green roofs.
This comprehensive analysis underscores both the potential benefits and trade-offs of using urban street trees as part of climate adaptation strategies for cities like Las Vegas.