Fallen trees: The root of the problem in Pasadena

Mother Nature’s blustery mood swing isn’t entirely to blame for the thousands of trees that crashed to the ground in the windstorm Wednesday night and early Thursday in and around Pasadena.

Improper care and inadequate growing conditions also played a role in felling much of the San Gabriel Valley’s urban forest, according to arborists helping clear debris.

“Almost every tree that I’ve seen toppled had no roots,” said Pasadena arborist Robert Wagoner, who has been supervising cleanup crews at homes on the north side of the city.

At the corner of Hill Avenue and Mountain Street, Wagoner spotted the remains of a 100-foot pine tree with a root structure only 10 feet across.

“It should be 30, 40 feet,” he said.

A 17-year veteran of the tree and landscaping business, Wagoner said he believes the root systems of many fallen trees weren’t given room to grow properly.

“We invade the root zones of trees with curbs, streets and sidewalks, and there’s a general lack of respect for tree roots among people who do construction,” he said.

Trees that grew in sprawling yards or park space, on the other hand, might have been destabilized by over-watering long before the winds finished them off.

That appears to be the case for three 110-year-old oaks and a 50-year-old pine that came down in South Pasadena’s Garfield Park.

“The oaks that were pulled out of the ground were typically in irrigated turf going up to the trunk, and their root systems were compromised because of that,” said Drew Ready, a member of South Pasadena’s Natural Resources and Environment Commission and a coordinator with the Council for Watershed Health. “Oaks were not evolved to survive with constant soil moisture.”

The root systems of trees surrounded by lush lawns rarely penetrate deep into the ground because the turf holds water near the surface. Over-watering can also loosen soil around roots or cause root rot and other diseases.

“In Garfield Park we lost over 10% of our significant trees, maybe closer to 20%,” Ready said. “If that’s the case in most of Pasadena, South Pasadena and San Marino, we’ll certainly have to think long and hard about our practices in parks and parkways.”

Javier Cabral, another arborist and landscaper in Pasadena, said parkway trees — those in the spaces between curbs and sidewalks or buildings — fared poorly.

“The ones that suffered more were the street trees,” Cabral said. “They get lush because the [smaller] feeder roots get water, but the support roots don’t develop well. Trees get big and heavy, and when the wind comes, they go down.”

Cabral identified another contributing culprit: the sluggish economy. Cash-strapped property owners who delayed having trees trimmed may have contributed to the damage.

“Trees don’t wait for the economy to get better to grow,” Cabral said.

Pasadena’s enthusiasm for its urban forest makes trees something of a third rail in city politics. In 2009, hundreds of residents gathered to protest the city’s decision to cut down ficus trees in the Playhouse district and replace them with another variety.

That passion may have served the city well this week. Wagoner said more trees might have come down if not for the city’s strict enforcement of ordinances that govern tree planting and care.

The city plans to replace most of the 700 or more trees that fell in the storm, though City Manager Michael Beck said the replanting would begin after the new year.

Mayor Bill Bogaard said the city is likely to replace fallen trees with others of the same variety.

“Because of the strong views about trees in the city, undertaking to revise or rethink any plan, while it’s always possible, would not be something done lightly,” Bogaard said.