SF Using Data-Mapping Tech to Count Its Trees — and Save Millions

While high-quality roads, appealing architecture and effective public transportation have long been seen as catalysts of economic growth, policymakers have paid little attention to industrial infrastructure’s arboreal counterpart: trees.

The Urban Forest Map — a visualization of every tree in San Francisco — seeks to change that. It turns out that trees too have economic and environmental benefits via their capacity to conserve energy, filter stormwater, capture air pollutants and remove carbon dioxide from the environment. With the help of local nonprofit Friends of the Urban Forest and tree inventory specialists ArborPro and Davey, the city calculated and mapped the economic and environmental value of each tree in the city in order to remind policymakers and residents alike of these often-overlooked benefits.

The city deployed a team of certified arborists in January 2016, and one year later, the team had identified the exact location, species and current condition of 124,795 street trees — more than 20,000 above previous estimates — as well as 40,000 vacant sites for future plantings. The Urban Forest Map relies on crowdsourcing to fill in any gaps in the data collected by the city, allowing users to add new trees as well as document stewardship activities like watering or pruning. And, as a means of appealing to residents on a more personal level, each tree also has its own Web page, and users are encouraged to upload photos to help tell trees’ stories.

The map shows that San Francisco’s trees provide significant value to the city. Drawing on the expertise of ArborPro and Davey, the city was able to estimate the energy conserved, stormwater filtered, air quality improved, carbon dioxide removed, and carbon dioxide stored by each tree, which the city then aggregated in a rating of total annual benefits in terms of dollars saved. Taken together, the city’s arboreal infrastructure saves more than $2.3 million per year, conserves more than 12 million kWh/year of energy, filters more than 100 million gallons of water, improves air quality by 55,000 pounds per year, removes 19 million pounds per year of carbon dioxide, and stores 77 million pounds of carbon dioxide. By comparison, the average American home consumes around 11,000 kWh per year of energy, and the average car emits around 10,000 pounds of carbon dioxide each year.

Thanks to this visualization, San Francisco policymakers and residents are more aware of the value of the city’s trees and can make more informed conservation efforts. The Urban Forest Map comes at a critical time for San Francisco’s arboreal assets following the passage of Proposition E in November 2016, which transferred street tree maintenance responsibility from private property owners to the Department of Public Works (DPW). Using the map, DPW employees can better track the location and condition of the city’s trees, improve their tree and sidewalk maintenance, and promote public stewardship of the city’s urban forest.

Similarly, the Los Angeles County Department of Parks and Recreation, under the leadership of CIO Mohammed Al-Rawi, has turned to tech as a means of preserving and better using that sprawling county's parks and forests. 

“Trees are one of the largest assets we have in county parks," Al Rawi said in a July interview with Techwire. "We have thousands of trees across our 182 sites. And as you know, trees represent big liability/risk, with many trees falling and causing unfortunate damages. We are going to implement soil sensors, wind sensors and video analytics to monitor those trees. Those sensors will provide data to predict a tree falling before it happens. Additionally, it will add a huge level of efficiency, as we currently check tree health at the county by sending arborists to each location.”

— Story by Chris Bousquet of Data-Smart City Solutions, an initiative of the Harvard Kennedy School, with additional reporting by Techwire. A version of this story previously appeared in Government Technology.