Because Trees Help Keep Pollution Out Of The St. Johns River, Jacksonville Is Mapping Them

Feb 28, 2019

With a grant from the U.S. Forest Service, Jacksonville has hired a Virginia-based nonprofit to study the city’s trees and how they can be better utilized to address the problems of urban stormwater runoff, among other things.

The city is hosting a public meeting on Thursday, February 28, where officials will discuss the study and seek input from residents. The event is scheduled to run from 6 to 8 p.m. at San Marco Preservation Hall, 1652 Atlantic Blvd.

The U.S. Forest Service funded studies in three Florida communities: Orange County, the City of Miami Beach and Jacksonville. Green Infrastructure Center Executive Director Karen Firehock said Jacksonville’s is the final project in the state, and her team is working to wrap up the study soon.

“Many cities in Florida are suffering from too much standing water and polluted runoff, as rainwater picks up pollutants on the streets and carries them into surface waters,” Firehock said. “This project is demonstrating how we can better utilize the city’s existing trees to capture stormwater and where we can plant new trees to also soak up additional water.”

Trees help because they capture and retain rainwater before allowing it to evaporate back into the atmosphere.  

“What that does is it sort of intercepts some water. That’s less water that’s falling onto streets and running off and causing standing water, flooding and other problems,” explained Firehock.

She says the problem in older cities like Jacksonville is that much of the area is paved, meaning there’s not as much space for trees to grow. Additionally, the city’s tree canopy is getting old.

“So if you have a beautiful live oak tree but it’s been there for a long time, it might be getting toward the end of its life cycle,” she said. “So if we don’t plant new trees, we’re not going to have that canopy in the future.”

The urban tree canopy is the layer of tree leaves, branches and stems that provide tree coverage of the ground when viewed from above.

Researchers are using detailed satellite imagery to map Jacksonville’s canopy and to show where trees should be retained because they’re already effectively soaking up water, as well as places where additional trees should be planted to help with the stormwater problem.

According to Firehock, Jacksonville’s canopy average is currently at about 42 percent, meaning “if you were a bird flying over the city looking down, 42 percent of it would be covered by trees.”

But downtown the tree canopy drops dramatically to about 10 percent.

“It’s not evenly distributed, so we want to find those places in the city where trees are lacking and try to add them so they can soak up water,” said Firehock.

While trees play a significant role in reducing urban stormwater runoff and improving water quality, they provide other benefits as well.

The power of trees in Jacksonville.
Credit Climate Central

Research from social scientist Kathleen Wolf suggests trees have socio-economic impacts like lowering crime rates, improving health, raising property values and they can even lead to people spending more time in shopping centers.

Plants also improve air quality and even help curb climate change and its impacts.

Trees absorb carbon dioxide, reducing greenhouse gas emissions and global warming.

Firehock said trees also help cool cities.

“You can find a difference of 12 degrees cooler under a tree versus out in the street,” she said. That also helps reduce energy costs. “It varies by area. It can be as much as 20 percent.”

Average annual financial benefits of trees.
Credit U.S. Forest Service

As Jacksonville’s Urban Forest Manager Richard Leon puts it, trees are the answer to many of the city’s issues.

“That’s why I’m in this position,” he said. “I honestly believe that trees play a role in mitigating all these things.”

Leon said the study will help the city figure out if there are any codes or ordinances that could be changed to improve the condition of urban tree canopies.

The city will host its final meeting on the study in Springfield on March 28.

Firehock said it’s great that the city is sponsoring these workshops, but most of the land in Jacksonville is privately owned.

“The way we are going to be able to be most successful is if community members and businesses plant trees on their own properties,” she said. “That will be critical, because a tree survives best when it’s got enough room and space to grow, and the best place for a tree is really in somebody’s yard. We can get them to survive on streets, but really, if we can get participation by community members that will really help.”

Photo used under Creative Commons license.

Brendan Rivers can be reached at brivers@wjct.org, 904-358-6396 or on Twitter at @BrendanRivers.