What Urban Tree Heat Stress Means for Greener Winnipeg Spaces

Urban trees do more than make outdoor spaces look better. They help cool neighbourhoods, support biodiversity, improve comfort, and make public spaces more inviting during warmer months. But a new University of Manitoba-based research paper highlights an important point: trees also experience heat stress, especially when they are surrounded by hard urban materials.

The study, titled “Do Trees Need Umbrellas?” Using Raytracing to Assess the Heat Stress of Trees in Cities, used digital modeling to examine how surface materials, building façades, and vegetation coverage can affect tree health. Researchers modeled 147 trees across 25 scenarios to examine how leaf temperature changed under different urban design conditions.

One of the clearest findings was that ground-level growing vegetation, including shrubs and prairie grass, had a stronger positive impact than façade vegetation. In the best-performing scenario, higher levels of growing vegetation reduced the risk of tree heat stress by 5.2 percent. By contrast, certain façade vegetation scenarios increased tree risk by up to 12.8 percent, underscoring the need to carefully evaluate urban cooling strategies rather than assume they work.

For Southwood Circle readers, the takeaway is simple: creating healthier outdoor spaces requires thoughtful design at ground level. Trees, grass, permeable surfaces, shade, and material choices all play a role in how comfortable and resilient a site can be during hot weather.

As Winnipeg continues to experience warmer summers, research like this helps communities, planners, and property owners better understand how outdoor spaces can support both people and natural systems.

For anyone interested in comprehensive technical research, the complete paper is available to download here.