Authorities are again looking for a tree-killing bandit after a second incident of vandalism in three months was discovered in a Dakota County public park.

Four mature black cherry trees were found girdled, or stripped of their bark, last week in Terrace Oaks, a city park in Burnsville. The damage likely will kill the trees.

"It does seem specific, like a certain type of tree was targeted and a certain size of tree," said Caleb Ashling, Burnsville's natural resources specialist. "We really hate to see really old trees with a lot of wildlife value at the park damaged."

The trees were large, ranging from 19 to 37 inches in diameter. There could be additional damaged trees that haven't been found yet, said Ashling, who came upon them while planning a habitat restoration project. He said the damage appears to have been done in the past several months.

Girdling damages and usually kills trees because it deprives the roots of nutrients that flow through the bark, causing them to starve.

In late March, about 30 black cherry trees were harmed in a similar fashion in Lebanon Hills Regional Park, which spans the cities of Rosemount, Eagan and Apple Valley.

A $5,000 reward was offered for information about the Lebanon Hills incident, the first offered in the county for property damage. So far, no one has been caught, said Chief Deputy Joe Leko of the Dakota County Sheriff's Office.

Those trees likely will die but haven't yet, Leko said.

The Sheriff's Office is looking into getting DNA off the bark, but it's a long shot, Leko said. "It's worth a try," he added.

The county may also place trail cameras near the site of the girdled trees, Leko said.

It's not clear that the two incidents are related; authorities don't know the motive behind the vandalism.

Leko said he has heard speculation that the trees were killed to increase the amount of sunlight in the area, allowing more morel mushrooms to grow.

It's also possible that someone hoped to harvest the trees after they die and dry out, Ashling said, adding that it would be "pretty difficult and pretty brazen" to do so.

"It's perplexing and sad to see large trees intentionally damaged like this," Ashling said.

Erin Adler • 612-673-1781