It has been an exciting month in the Urban Forestry derring-do. We have begun to install data loggers throughout the City of Tumwater that measure the ambient air temperature. We’ve placed these data loggers throughout the city to examine the difference in ambient air temperature in areas with tree canopy coverage versus those without.  For instance, the first data collection on June 30 showed that the 5th and Hayes Pocket Park (on Tumwater Hill) was 5.5°F cooler than the Capitol Little League Ballpark (near the Airport) at 7:30 a.m.   

Research shows that trees can lower temperatures by as much as 15˚ F in the day and as much as 25˚F at night.  Trees “transpire” which means they release tiny molecules of water to lower the temperature around them, as well as provide shade.  The reason for the higher temperature alleviation at night is that asphalt absorbs heat considerably.  If we can prevent that absorption with shade, then we will see increasingly larger benefits at night. These data loggers will help us identify important areas where tree planting should be increased as our climate warms.