The Planting Fields Arboretum State Historic Park in Oyster Bay lost a few of its dozens of trees while many others were damaged by Tuesday's powerful though brief hailstorm, according to the state parks department.

Dangling tree limbs and debris blown onto the walkways forced park officials to close the former Gold Coast estate to the public Wednesday, though it will reopen Thursday.

"It was a surprising storm, it only lasted about 15 minutes," said Randy Simons, a spokesman for New York State Parks, Recreation ... Historic Preservation.

Though not nearly as destructive as superstorm Sandy in 2012, this storm's hail, about the size of quarters, broke about 20 window panes in the Camellia Greenhouse. Oaks and pines had the most damage; two of the toppled trees had stood for more than a century.

"This is the time of year when trees are at their most vulnerable," Simons said. Not only are their branches bearing all their leaves but the trees are full of water, he said.

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Both factors increase their weight. Yet the ground also can be waterlogged, weakening the roots' ability to anchor thousands of pounds, Simons said.

Concern that broken branches might fall on visitors, a problem seen in Central Park a few years ago, is the main reason officials closed the arboretum's 65-room Tudor Revival mansion, greenhouses, lawns, formal gardens and woodland paths to visitors.

"We just wanted to clear all those out, and remove debris," Simons said. Hauling away downed trees and trimming damaged ones could take a few weeks. "We'll have to prune them back to make them whole again," he said.