Pines in peril

Photos Megan V. Winslow/Town Crier
Arborists with S.P. McClenahan of Portola Valley cut down a Monterey pine tree behind Los Altos Hills Town Hall, above. The tree, located in a resident’s backyard, was dying due to bark beetle and drought. A pitch tube, right, upon a Monterey pine tree’s bark indicates where bark beetles have bored into the tree.

It seemed like a good idea at the time: offer free Monterey pine seedlings to Los Altos Hills residents who promised to plant them. Heck, Tree-Planting Committee Chairman Bill George would even dig the holes for free.

“If the homeowner would rather buy his own trees, that’s jake with George, too, just as long as they’re not larger than 1-gallon size,” read a Jan. 8, 1969, Town Crier article. “Bigger than that, dig your own hole.”

Nearly half a century later, those seedlings are behemoth trees towering over – and sometimes crashing down on – Los Altos Hills’ winding roads. A combination of stressors, including drought conditions and pests like fungal disease and voracious bark beetles, are accelerating their death. Locally, the Monterey pine has eclipsed the invasive eucalyptus as species most commonly flagged for removal, said Kevin Kielty, an arborist contracted by the Los Altos Hills County Fire District to survey trees.

In June, one Monterey pine fell across a West Loyola Drive driveway and onto a departing pickup truck. The crunched cab trapped the driver, the vehicle’s single occupant, until Santa Clara County Fire Department first responders freed him with the Jaws of Life. The man suffered minor injuries.

Local origins

According to the U.S. Department of Agriculture, the Monterey pine is the most widely planted pine in the world, a distinction the conifer largely owes to its rapid, lush growth. But the species has a limited ecological tolerance and is native to only a handful of regions, including the California’s Central Coast. It relishes moist, maritime weather and is not, in fact, well suited to Los Altos Hills and communities with similar climes.

The Monterey pine’s temperamental nature was not well known to early Bay Area settlers, however, and as recreational areas like Golden Gate Park, the Presidio and McLaren Park sprang up, they were populated with the evergreens. By the mid-1950s, the U.S. Christmas tree industry marked a swing from fir and spruce to pine, and Bay Area tree farms began growing and selling the Monterey variety.

Many of Los Altos Hills’ homes were constructed between the 1950s and 1970s, and it was during that 20-year window that most of the now-troublesome local Monterey pines were planted. They were abundant at nurseries, doled out for Earth Day celebrations and even provided gratis by the state; in 1974, California officials gifted Los Altos Hills with 10,000 trees – Monterey pines, Douglas firs and redwoods – for planting along properties adjacent to Interstate 280. There they would serve as a living screen and noise buffer.

“They were the least-expensive tree at the time that established as quickly and grew as fast as it did, and it provided screening between properties – that’s why most of them are near roads and near property lines,” said Joshua McClenahan, chief operating officer of S.P. McClenahan, the fire district’s contracted arboriculture company.

The threat

Here’s the problem: Drought, the fungal disease pitch pine canker and the dreaded bark beetle all wreak havoc on Monterey pines. Beetle varieties including the Western pine, the engraver and the red turpentine bore under the tree bark and lay eggs, and their larvae devour the living tissue between the bark and the wood surface. The insects can skeletonize a tree within a matter of weeks.

Stressed by years of drought, local Monterey pines are living only half of their traditional 100-year lifespan. And their removal has kept the S.P. McClenahan company busy. Joshua McClenahan June 8 visited a site behind Town Hall where a three-man team worked to fell a beetle-infested tree.

“This tree, a terrible candidate when it comes to drought and bark beetle,” McClenahan said. “And it’s lived through three or four drought periods in its time, since, let’s say, the ’60s. So in its 50 years of life, it’s not gone through just one drought but a series of them, which has all contributed to the stressors – and then the heavy bark beetle infestation.”

The Los Altos Hills County Fire District launched its Dead Tree Removal program in 2011 to cut down on potential fire fuel sources and to help prevent accidents like the one on West Loyola Drive. Between July 1, 2011, and June 30 of this year, the district facilitated the removal or pruning of 8,546 trees, the majority of which were Monterey pines.

Here’s how the program works: The district mails postcard notifications to residents of Los Altos Hills and connected portions of unincorporated Santa Clara County; residents respond with tree removal requests; an arborist like Kielty inspects the trees; and an arboriculture company like S.P. McClenahan removes approved trees.

Tree removals are “free” to residents, though they essentially fund the program through property taxes. In fiscal year 2015-2016, which ended June 30, the district budgeted $2.8 million for hazardous tree removal and spent $2.6 million. For fiscal year 2016-2017, $1.5 million is budgeted.

“Since the first four years of the tree programs have seen the bulk of dead or dying trees pruned or removed, expenditures for FY17 are expected to decrease significantly,” according to the budget narrative.

The program is “tremendously helpful – there’s no question,” said Duffy Price, fire district commissioner. “Everybody just raves about it. We’ve received letters from residents thanking us.”

McClenahan said it’s important for residents to recognize the signs of a stressed Monterey pine and notify the fire district before the tree becomes too compromised for arborists to climb and cut safely.

Look for browning or missing foliage, sawdust-like frass at the base of the tree and, on the bark, leaking sap, beetle emergence holes and rust-colored pitch tubes resembling festering sores. Bark beetles can fly and readily infest multiple trees.

And if not covered by a gratis tree removal program like the fire district’s, be sure to hire a reputable arborist, McClenahan said. Qualified companies are listed on the Tree Care Industry website ( The International Society of Arboriculture website ( features certified individual arborists.

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