As planners, we know that trees are a valuable resource which contribute to a community’s wellbeing in many ways.  It’s obvious to most people that trees serve an aesthetic purpose, but the more scientific calculations of a tree’s environmental impact, translated into a dollar value, can be more obscure.  That’s where the San Diego County Tree Map (www.sandiegotreemap.org) takes our urban forest to the next level of public awareness.

Launched by the California Center for Sustainable Energy (CCSE) on March 1st, the map has become a reality thanks to the efforts of Robin Rivet, an urban forester with CCSE.  After creating an Urban Forestry Resource Center (located within the CCSE) and an online tree information resource (www.sandiegotrees.org), CCSE obtained a grant to create the online tree map.

“This truly is a community project to understand the impacts of trees, from conserving water and cleaning the air to saving energy and reducing greenhouse gas emissions,” explains Rivet.  “We hope that over time, citizens will enter additional trees from residences, parks, and schools and other public and private areas.”

Containing a population of 300,000 trees with data gathered from 13 cities, the number of trees recorded on the map should grow quickly.  Initial map data was collected from various sources, such as certain municipalities and tree care companies.  One of the best features of this map is that the data collection is “crowdsourced.”  This means anyone is able to register with the site and add trees or edit details about existing trees.  All trees within the County can be mapped, from street trees to trees in a park, to trees in your backyard.

After entering details like the tree species and caliper size, the map calculates an environmental and economic value that the tree contributes.  For example, the landmark Moreton Bay Fig tree, located adjacent to the Natural History Museum in Balboa Park, is listed as having a diameter of 100 inches.  Based on the size and species, the tree provides these “yearly ecosystem services”:

Yearly ecosystem services

Value

Energy conserved 183.30 kWh $29.84
Stormwater intercepted 2045.08 gal $3.74
Air pollutants removed 1.03 lbs $66.43
Carbon dioxide reduced 135.99 lbs $2.72
Total Co2 stored to date 5903.65 lbs $118.07

 

In addition to the values calculated by the map, Rivet notes that studies show trees also improve health, increase property values, lower crime, and attract customers to business locations.  Of course, trees are also an essential component of “Complete Streets” and act to slow traffic and create more pedestrian-friendly environments.

The tree map is based on Google Maps basemap data and incorporates software developed by the U.S. Department of Agriculture Forest Service Pacific Southwest Research Station.  Funding was provided by the California Department of Forestry and Fire Protection, which also provides support for CCSE’s Advice and Technical Assistance Center for Urban Forestry.  This center is open to the public and is located in the Energy Resource Center at 8690 Balboa Avenue.

Garnering community support for ownership of the urban forest and making trees a priority in the municipal budget process can be a challenge.  The tree map acts to both engage the community and enables people to realize the value trees deliver, down to the last penny.