LINCOLN SQUARE — Eric Rojas doesn't blame the person who reported his sycamore to the city's Bureau of Forestry, even though that action touched off a sequence of events that nearly caused city crews to send an innocent tree to the wood chipper.
"Legitimately, it looked bad," he said of a fissure that opened up in the tree's trunk during the recent arctic blast. "The gap went midway up."
Though outward appearances suggested the tree was about to come crashing down on nearby cars and homes, what the anonymous tipster didn't know was that the tree's outer bark has a history of splitting during cold weather and then closing back up.
The phenomenon is called freeze or frost crack, which happens during low temperatures, according to Doris Taylor, a plant specialist at the Morton Arboretum.
A sudden drop in temperatures can produce a fracture along a previous wound, perhaps one caused by a botched pruning job, she said.
In Chicago, freeze crack is typically confined to sycamores, which make up a small percentage of the city's parkway trees, according to John Lough, senior forester with the Bureau of Forestry.
"We haven't seen it for several years," he said. "It's not something that occurs that commonly."
Rojas had been warned of the tree's quirk when he and his wife purchased their home in the 2200 block of West Winona Street more than three years ago, but he'd never witnessed the peculiarity until the week of Jan. 6.
Last week, a neighbor alerted Rojas about a city employee who was hanging a "do not park" sign on the tree, which sits in the parkway and provides a significant canopy of shade when in bloom.
Rojas approached the worker.
"He said, 'They're going to cut the tree down tomorrow.' He said, 'It's dangerous; it's cracked all the way up,'" Rojas recalled. "I didn't know what to think."
Longtime residents of the block, who'd experienced similar situations with their sycamores, persuaded him to fight for the tree, which they insisted was not a hazard.
His first call was to the office of 47th Ward Ald. Ameya Pawar.
"They gave me a direct phone line to forestry," Rojas said.
After sharing his story with a forestry supervisor, Rojas received an assurance that the order to chop down the tree would be canceled. He later learned the supervisor himself came out that same evening to look at the tree and confirm its health.
"Normally when our inspectors are out, cracks are viewed as a severe structural flaw. Our first priority is safety," Lough said.
Even though a freeze crack eventually closes, he added, insects and pests can enter while the bark is open and cause internal decay.
Rojas said he doesn't fault anyone for believing the tree posed a danger, but the "communication faux pas" that came next is what left him disconcerted.
The day after speaking with the supervisor and being told the removal order had been rescinded, "two huge city tree-cutting-down trucks come pulling up," Rojas said.
Worried they were preparing to remove the tree, he reached back out to the city.
"I called the same number for Forestry and said, 'I've got two trucks here with guys.' Five minutes later, the trucks were gone."
If he hadn't been home, the perfectly healthy tree could have hit the wood chipper.
"My issue was that they could have cut it down without anybody knowing," he said. "There should have been some attempt to knock on doors."
Lough said personally contacting homeowners isn't always practical or efficient, but stated, "Typically, we're not removing trees unless we absolutely have to."
A week later, on a downright balmy afternoon, Rojas posed next to the still-standing sycamore. The split was nowhere to be seen, the crack having already healed.
"If we weren't here, they would have just torn it down, and it didn't need to be," he said.