The trunk of a massive valley oak tree snapped Tuesday night in Doyle Park, sending the majestic tree crashing into a dog park, according to Santa Rosa Recreation and Parks officials.

The tree, which was at least 20 feet in circumference, still lay surrounded by yellow tape Friday morning. Some branches had been trimmed, and part of the dog park fence had been mangled by the downed tree.

Parks supervisor Tom LoCoco said that the city would begin removing the tree next week using a crane.

"Where it is lying right now, it is stable," he said. "It was one of the larger trees in the park."

The parks department's arborist was not available Friday, and LoCoco said he did not know what caused the tree to topple.

Some park users said that they suspected the tree had been rotten. The valley oak species is not susceptible to sudden oak death, a disease that has killed more than a million trees in California.

Cecil Rhodd, who walks his dog in the park daily, said a friend who was in the park Tuesday night, told him that she heard a cracking noise that lasted for about four minutes before the tree toppled.

"That's the biggest fallen tree I've ever seen," he said. "I'm lucky I wasn't under it."

The National Weather Service reported winds of up to 15 mph in the Santa Rosa area Tuesday night. A high-wind advisory was issued Thursday night with average winds of 30 mph and gusts up to 50 mph.

This is not the first incident of a downed tree in Doyle Park since the city acquired the oak-studded, 22-acre site nestled between Matanzas and Spring creeks in the 1950s. In March 1977, an oak tree with rotten roots fell early in the morning before visitors arrived.

A large oak in 1979 crashed onto a station wagon full of teenaged park visitors. In 1988, a 70-foot Doyle Park oak snapped injuring eight picnickers.

The city removed an aging valley oak tree at the entrance to Doyle Park in 1992 because of the danger that its deteriorating branches posed to visitors.

A February 1998 storm that brought high winds to the area and toppled a 125-year-old oak in Doyle Park. In 2007, the city found that a dying Doyle Park coast live oak had sudden oak death.

Doyle Park regular Song Sheridan waxed philosophical as he gazed at the downed oak Friday morning.

"The park is just engaged in the cycle of life," said the Santa Rosa musician and poet. "You're born, you live, you die and you become mulch."

You can reach Staff Writer Matt Brown at 521-5206 or matt.brown@pressdemocrat.com.