SEATTLE - Someone has intentionally poisoned seven mature trees along the Burke-Gilman trail, city officials said Thursday.

Three silver poplars and four Douglas firs along the trail 77th Avenue Northeast were found dead or dying by Seattle Parks and Recreation staff on a routine maintenance visit. All the trees were about 70 feet tall.

Each tree had quarter-inch holes drilled in it, spaced about one inch apart, all the way around the trunk. Due to the rapid death of the poplars, experts believe herbicide was likely injected in the holes.

"This loss is significant," said Parks and Recreation Superintendent Tim Gallagher, "because there are so few conifers in this area of the trail. No matter how often private citizens damage publicly owned trees, it is always shocking."

The three poplars are already dead, two of the Douglas firs are dead, and the other two are starting to turn brown.

The trees are about 30 years old and have an estimated value of $40,000 to $60,000, officials said.

A police report has been filed, and officers are investigating the tree killings. Anyone with information about how the trees may have been vandalized is asked to call the Seattle Police Department at 206-625-5011.

The city seek full damages if police can identify the person who committed the vandalism. This crime could be prosecuted under the State Malicious Mischief statute or under the Timber Trespass Statute.