You do not have to be a nature enthusiast to appreciate the planting of spaced-out trees alongside city sidewalks, giving a splash of color and life to the urban surroundings. However, because of the way they are grown, these trees often struggle or die, ending up just as gray and lifeless as the buildings around them. But acclaimed environmental designer Vanessa Harden, who specializes in incorporating natural systems into urban settings, has found a potential solution.
On Friday, Nov. 14, Harden held a talk for the University of Connecticut’s Plant Science and Landscape Architecture department in the Wilfred B. Young Building. She dived into her research behind her recent design, called “soil conduits,” which aims to address tree health in urban settings.
Harden explained that trees in the wild can connect and communicate with one another through mycorrhizal networks. These systems form from fungi in the soil, which branch out with root-like structures called mycelium. Trees can pass along nutrients through these connections, allowing older or flourishing trees to support ones that are younger or struggling. When Harden learned about these interactions, she started considering whether they work in urban environments.
“I was originally from Montreal, and I thought, ‘How is it possible for these trees to communicate?’” Harden said. “Well it’s probably impossible, right, because they’re individual cells. So there’s no way for them to actually communicate in the same way that they do in forests.”
After some thinking, Harden brought the problem to the Harvard University Graduate School of Design, where she began researching the issue. She started her research by immersing herself in existing studies about the benefits of fungi networks for trees and environmentally friendly urban infrastructure projects.
Through her background research, Harden found that certain tree species could connect with over 45 other trees from up to 30 meters away. She also took interest in design work from James Urban, who focused on root expansion systems for trees in cities.
Harden then worked on the design itself, which took the form of what she called “soil conduits.” She planned for them to be small tunnels filled with soil that run between isolated trees in cities, with some trees connecting to parks or wooded areas when possible.
Because the soil requires air circulation for the fungi, the conduits would require grates and a workable drainage system. Balancing all these needs led to an involved design that could be difficult to implement, so Harden foresees using it where urban infrastructure is already changing, and new trees will be planted.
“This is something that I see for cities that are expanding, or…if there’s a gas leak and we need to pull up the sidewalk, and we can implement this technology at that particular time,” Harden said. “It’s the newer trees right now that are dying…with a high mortality, so it’s important to give nutrients to the newer trees, especially in the beginning of their life.”
To test her research, Harden conducted a year-long greenhouse experiment. She compared a sample size of trees with a model of her soil conduits, another group with Urban’s root expansion systems and a control group with neither. She measured the plant growth along the way and was able to measure the length and density of mycorrhizal connections between the trees at the end.
“Some of the trenches went halfway, some of the trenches went both ways and only one trench went completely, and there was full connectivity,” Harden said. “Which we were able to say was the success of the project, essentially, that there was full connectivity.”
Even though one of her tested soil conduit systems was a complete success, showing it could mimic the fungi connections found in the wild and that it benefited the tree’s growth, Harden hopes to expand her research to take more factors into account. She said there could be more to test by taking different tree species and fungi types into consideration.
Harden has already started to implement her soil conduit design in urban areas. She has worked with a real estate developer to incorporate the system into a parking lot, where it connects trees to central islands.
“We designed a slightly different but conceptually similar soil conduit for the parking lot,” Harden said. “We’re only going to find out in probably three years if it’s working or not.”
Keston Sun, a third-semester molecular and cell biology major, was not aware of the fungi networks that helped trees communicate before the event. But after learning about Harden’s soil conduit system, Sun was sold on the idea and its potential benefits.
“I am hopeful that, with this innovation, trees can make a comeback in urban environments, which could help improve the local quality of life,” Sun said.
Harden ended the talk by saying it can be difficult to get the public invested in environmentally friendly infrastructure, especially when it addresses unseen problems, like fungi connectivity. But she said that finding ways for people to engage with these natural processes and see how they work can foster more awareness about environmentalism.
“As cheesy as this sounds, I think most people need to get out of the city,” Harden said. “It’s about understanding and having empathy for non-humans…. People have to be interested, they have to see, and in order to see, you can bring people where they can see it.”