Friends of the Urban Forest and Proposition E

The past 6 months have been very important for San Francisco’s urban forest. The passing of Proposition E, which was on the November ballot, transitioned the responsibility of tree maintenance from homeowners to the city.

Leading up to this ballot measure, the city completed a comprehensive inventory of all trees in San Francisco (tree list and tree map available on SF Open Data). Every tree in the city was counted, it’s condition was reported, and the surrounding area was investigated. The Data Science Working Group partnered with the Friends of the Urban Forest  (FuF) to help extract useful insights from the data to encourage voters to support Prop E.

First, we explored the data to determine which metrics would be useful to quantify and visualize. Below, we have the density of trees throughout the city.

Tree density map of San Francisco

We also looked at a distribution of the top species of trees in the survey.

Following this exploration, we determined a set of metrics that might be interesting to voters. These metrics were sidewalk damage, tree density, number of vacant lots, species diversity, and tree health. The code we used to determine these metrics can be found here.

We decided that overlaying these metrics on a neighborhood map of San Francisco would be the most effective method of visualizing the impact of the urban forest. As a first pass, we built basic map with the metrics in a dropdown at the bottom. To make this a little more visually appealing, we moved this map to Tableau and added a brief description of the metrics.

A screenshot from Tableau

We found a number of interesting things in the data. First, tree health was the worst in areas we didn’t expect such as the Twin Peaks area. Additionally we were surprised by the large number of empty tree planting locations in the outer Richmond. While we saw a number of interesting things, we recommend you explore the data yourself. It turns out there is a lot going on with San Francisco’s urban forest!