We’ve completed year two of our Bicycle Tree Monitoring internship program. Our 2014-2015 intern, Irona Lee, has been working to monitor recently planted trees. Most tree mortality in an urban environment occurs within the first 2-10 years after planting. The goal of the tree monitoring program is to collect data about trees (health, growth, maintenance needs) through the city, so that volunteers can respond to help trees survive. Check out Irona’s report below to see how our young trees are doing in Davis!
Larger tree canopies yield greater benefits. Cities can maximize the benefits of trees by selecting the largest canopy tree for the available planting space. The surface area of a tree’s leaves covers between 2 and 8 times the area directly covered by the tree. As a result, larger tree canopies result in improved air quality, cooler summer air, greater reduction of storm water, better water quality, and reduced demand for summertime peak electricity.
100 trees remove 5 tons of CO2 and 1,000 lbs of pollutants per year.
Water Quality and Runoff
100 trees save $550 annually in storm water infrastructure costs.
Shaded pavement can last 50% longer before needing resurfacing with slurry seal. This saves our communities $30,000 per mile in road resurfacing costs.
Cars in shaded parking lots release 18%-21% less hydrocarbon emissions due to heat-induced leakage. Cabin temperatures are up to 60 degrees Fahrenheit lower.
From: E. Gregory McPherson, James R. Simpson, Paula J. Pepper, Qungfu Xiao, Guidelines for San Joaquin Valley Communities, March 1999
Plants in parking lots have been traditionally used for aesthetics and traffic guidance. Regulations generally mandate the quantity and distribution of plants, including trees, based on the size of lots. Increasing emphasis is placed on the ecological services and benefits of urban vegetation, a trend that can be seen in laws regarding parking lot trees. Davis, a small city about 20 miles west of Sacramento, California, was one of the pioneers of parking lot shade regulations. Davis’ ordinance requires that all parking lots be 50% shaded by tree canopy 15 years after development. Although the regulation has been in place for nearly 40 years, there are been no enforcement of shade coverage. The city partnered with Tree Davis to monitor parking lots in 2006 and 2007, but the project was terminated soon after due to budget cuts. In 2013, a Tree Davis intern revisited parking lot shade regulations in Davis as well as other cities in the U.S. The report titled “Parking Lot Shade Regulations: Review and Recommendations” is a summary of that work.