As conservation efforts continue to take effect during the California drought, many trees in parks and city streets are succumbing to the dry conditions, raising concerns among area residents.
On Tuesday, a massive tree came crashing down outside a children's museum in Pasadena, injuring at least nine children.
Witnesses said there was "no warning" when the 75-foot pine tree snapped and fell to the ground in Brookside Park outside Kidspace Children's Museum.
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While experts cite several reasons for the downfall, weather conditions may be to blame.
Botanic consultant Frank Mc Donough of the L.A County Arboretum says fungus, which spring to life during a rainfall and after a dry spell, is one of the reasons why trees fall to their death.
"It will encapsulate itself in buried wood, hunker down for years at a time until conditions are right," McDonough said. "It goes into the crowd, eats up the crown, and the tree falls over."
McDonough also attributed the collapsing of trees to a "summer limb drop," which he described as a tree that already has a high center of gravity or compromised rootbase.
He says, it normally happens to trees that are irrigated in high humidity during the summer.
"Water goes rushing up into the tree towards the leaves and instead of being evaporated out because of the high humidity, the limbs get very heavy and eventually they break or snap off," said McDonough.
Trees can also get tied up in their roots, McDonough said, making them more of a risk to toppling over.
On Wednesday, an arborist examined the tree that came crashing down outside the Pasadena museum, but there was no word on what may have caused the tree to topple
Kidspace Museum CEO Michael Shanklin says the city regularly maintains the trees on the grounds and sends an arborist to examine them at least four times a year.
The incident remains under investigation.
Jessica Perez contributed to this report.