By Alison Hewitt
Trees intercept solar radiation before it reaches the ground and release water through evapotranspiration, consequently cooling the surrounding microclimate. Surprisingly though, the air and surface cooling benefits of a tree over a paved area are not as great as they are on the nature strip or in a park on extremely hot days (Figure 1).
"Tarmacs and concretes absorb heat from sunlight and slowly release it into the air, while grass surfaces reflect sunlight. In this way the radiant heat from a paved surface diminishes trees' cooling benefits" says Western Sydney University PhD student Mahmuda Sharmin.
"We see that different man-made surfaces yield different temperature effects, as do different tree architectures and traits such as height, canopy width or leaf size".
The research indicates a need to keep our natural surfaces in the nature strips and move away from maximum paving or artificial grass in these contexts. Leading back to our long-held truism: underneath the trees in a park or backyard are indeed among the best places to be on those hot days of summer!