A comparison of the ameliorating effects of native and exotic street trees on surface heat retention at dusk

• This study compared surface heat amelioration between native and exotic street trees.
• Surfaces under native vegetation exhibited lower temperatures when compared to exotic vegetation.
• Exotic vegetation exhibited a wider range of temperature differences under their canopy.
• This research highlights how species consideration is important in green city plans and schemes.

Urbanisation results in a host of adverse environmental conditions often associated with an increase in temperature. Increasing urban vegetation, particularly street trees, may help alleviate higher temperatures as street trees play an important role in providing shade. We compared the potential for exotic and native street trees to help reduce surface temperatures in urban climates. The surface temperature of asphalt surrounding (or adjacent to) 6 species of street trees (3 exotic and 3 native) at 8 sites each were recorded using a FLIR Infrared camera on hot and normal temperature days. Surfaces under native trees exhibited lower temperatures when compared to exotic trees (lower by 2 °C). This suggests that there are some characteristics of native vegetation such as the density of shade or air flow that influence the surface temperature. Our study suggests that native vegetation is more efficient at ameliorating increased urban temperatures. Further work should identify the mechanisms by which street trees influence surface temperatures.