How Austin’s Map of Trees Helped City Leaders See and Tackle Social Inequities

June 23, 2021 by admin
Policy/Legislative

In Austin, Texas, like many places, the numbers of trees in neighborhoods mark a divide of race and income.

For Austin, the correlation can be seen in tree canopy maps that city staff have overlaid with demographics and other data using a geographic information system (GIS). In west Austin—the area west of Interstate 35—tree canopy covers 78 percent of the land. In east Austin, tree canopy covers only 22 percent.

“It’s really interesting that Interstate 35 is also a dividing line for ecoregions,” said Alan Halter, a senior GIS analyst with the City of Austin. “If you go west, you get into the Hill Country, with a lot more tree cover, but east Austin hasn’t historically supported as many trees. And when you look at who lives where throughout Austin’s history, communities of color have resided in east Austin.”

Inequity in Numbers of Trees

In 1928, Austin’s Master Plan (a term no longer used due to its racial connotations) relegated the city’s Black communities to a district east of present-day Interstate 35. Redlining made it nearly impossible for residents to move, while it placed fewer restrictions on white residents to purchase homes in Austin’s heavier-canopied parts of town.

The 1950s locked in environmental injustices, when the planning commission zoned all east Austin property as “industrial,” affecting nearby residents with the area’s lower air quality, higher temperatures due to a lack of tree cover, and other health-related issues.

This common pattern is found throughout the world—the prevailing winds, blowing west to east, bring pollution to the eastern parts of town.

When Halter first mapped Austin’s trees, he was focused on the city council’s urban forest plan.

“I created the first Community Tree Priority map back in 2015, and it was really tree-planting oriented—to figure out where to plant trees,” Halter said. “At that time, equity was a consideration but wasn’t really a main focus. We were mostly looking at where tree canopy existed and didn’t exist, with the idea to increase shade across town and get trees where they’re not currently located.”

As Halter added layers of data to the map, he saw the relationship between socially vulnerable neighborhoods and areas with minimal trees. In the wake of Black Lives Matter protests, equity became a strong focus of the Austin Community Climate Plan, so the map needed to change.

“We released an update in 2020 with equity as the driving force,” Halter said. “We’re now looking at tree planting to achieve positive outcomes for people, such as improved public health; reduced heat-island effects; and, of course, addressing climate change, because it’s related to everything.”

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Christopher Thomas