The World Beneath Your Feet

There’s just something special about Lincoln Park Zoo. It has that…je ne sais quoi. It’s the fresh air as it hits your lungs. The picnics on South Lawn with loved ones. The perfectly-timed shady spot you sat in while indulging in an ice cream cone. It’s the whole other world happening above your head and below your feet. Whether or not you’ve paid attention, the historic trees across zoo grounds are an integral part of what makes this park an oasis in the middle of the city. It may be easy to observe the active canopies full of migrating birds, nosy squirrels, and beautiful leaves, but it’s what you can’t see beneath the soil that helps these trees grow.

Many of the trees at the zoo predate the founding of Chicago and made this their home long before the zoo came along. But while we are utilizing their shade and the fresh air they provide and enjoy the changing colors, we inadvertently compact the soil surrounding the trees, minimizing the trees roots’ ability to get the water they need to thrive. That’s where the zoo’s dedicated team of horticulturists come in!

Sometimes, after a compaction event, such as years of foot and vehicle traffic, root invigoration may be necessary to help a tree survive. Root invigoration is a process aimed at repairing damaged soil and promoting the growth and repair of fine roots. First, the ground is irrigated in various spots to help get to appropriate moisture into the soil. Then, a special tool is used to blow air into the soil to excavate and till said soil without disrupting the root system.

To date, the zoo has already conducted this process for the zoo’s most at-risk and oldest trees including the oldest bur oak on South Lawn, the large bur oak near West Gate, and the large American elm near Searle Visitor Center. Beginning this spring, the process will expand to many of the trees across South Lawn—so if you see these trees getting a much needed spa day, you know why!

“We’ve seen great success so far,” says Director of Horticulture Katrina Quint. “This process provides improved soil conditions for the trees which allows them to live the longest lives possible in our urban environment.”

The root invigoration process can be beneficial to trees of all ages and sizes to help prevent decline. “Even at your homes the installation of a new sidewalk or driveway can be a significant compaction event,” says Quint. “If you notice signs of decline, check with a certified arborist to diagnose the issue and find the proper treatment.”