SEA was able to get the GIS department of the City of Redding to work up some tree canopy coverage figures for several areas of the City of which we will give more details next month’s newsletter.
We asked the City to drawn up maps for the core of downtown Redding running basically from between West St. and Continental Street on the west and east respectively and between Trinity Street and Cypress Ave. on the north and south respectively, generally excluding most but not all residential areas. This showed the total canopy in this area to have 12.1% tree cover, however, for trees over 40 feet in height, the canopy was only 1.6%! For trees between 7 and 15 feet tall, the canopy cover was 5.6%. This means the canopy for shade trees over 15 feet tall was only 6.5% and is this is based on 2020 mapping.
For the Garden Tract, basically between Continental Street and Park Marina Drive on the west and east respectively and between Locust and Yuba Streets (excluding Sequoia School and the commercial lands on Park Marina Drive) the tree canopy was 30% with 18.4% tree canopy with trees over 15 feet tall and 11.6% for small trees between 7 and 15 feet tall.
Scientists studying the heat island effect believe that a tree canopy in a city should be at least 40% to counteract the heat island effect. The heat island refers to the amount of solar radiation absorbed by areas such as streets, = parking lots, buildings, sidewalks and rooftops. The difference can be as much as 12 degrees between a tree canopy area such as the natural area of Turtle Bay and a typical city downtown area with few trees according to the NOAA.
Nighttime temperatures can have as high as a 22 degrees difference between an urban area and an adjacent countryside. This is because the asphalt and concrete etc. not to mention air conditioners, continue to radiate heat well into the night whereas the treed countryside continues to cool after sunset. This is why Redding needs a new tree ordinance that preserves and/or mitigates for the loss of trees.