Presidio sticks with its roots for historic trees 

click to enlarge Trees in the Presidio of San Francisco
  • Mike Koozmin/The S.F. Examiner
  • Peter Ehrlich, the Presidio Trust's forester, who has for the past decade been leading revitalization efforts of the trees at the former military base.

Wind was the problem. Trees were the solution.

The strong ocean breeze that batters the Presidio today was an even more malevolent force in the former military outpost's early days. It pushed sand under doorways and through windowsills, which literally piled up in kitchens.

The simple logic of the Army's largest horticultural experiment -- carpet-bombing the sandy dunes of the Presidio with trees from 1886 to 1900 -- was a solution that eventually turned into a problem. In that short span of time, the Army populated the area with Monterey pine and cypress, along with the ubiquitous Tasmanian blue gum, better known as the eucalyptus tree.

After the planting, the Army all but forgot about its arboreal creation for nearly 100 years. When the last soldiers packed up and left in 1994, those windbreaks, by then an unkempt and unhealthy 300-acre forest, were in shambles.

"The forest was in decline," said Peter Ehrlich, the Presidio Trust's forester, who has for the past decade been leading revitalization efforts. The Trust manages the former base.

Those efforts have included pruning and planting a tree that other locales -- nearby Angel Island, for instance -- have worked hard to remove.


It could be said that no tree in California is as common or as controversial as the eucalyptus, which started to fall out of favor in the 1980s. It's reviled by some as an invasive species that must be eradicated, and defended by others as part of the state's polyglot flora. On Mount Sutro, for instance, neighbors are fighting UC San Francisco's plans to thin the forest, while huge stands grow unabated atop parts of the Marin Headlands.

The Presidio is not tearing out its eucalyptus forest for a simple reason: It's not allowed to. Many of the area's trees -- mostly pine, cypress and eucalyptus -- were planted more than a century ago and are under protected status.

"We want eucalyptus here because it's part of the historic designation," Ehrlich said. "We have to do it because it's a cultural forest."

That designation came in 1963 when the U.S. government declared the Presidio a National Historic Landmark District.

Therefore, the park's forest cannot just be formed at will. Part of it must be kept intact because of the Army's planting efforts, while other parts are being restored to original habitat.

That, according to Ehrlich, entails making it a healthy place for trees of all kinds, native and non-native.

"We're trying to understand the unique qualities of this place, to experiment, and not import artificial ideas about how to care for the forest but actually develop indigenous ways of thinking about it," Michael Boland, chief of Presidio planning, said of their approach to managing the forest.

In the past decade, the Presidio Trust, which manages the area, has as part of its reforestation program planted 3,500 trees: redwood, oak, cypress and pine.


Ehrlich was the urban forester for the Recreation and Park Department before coming to the Presidio Trust in 2001. He said that when the Army planted the trees that now cover the former base, it used as a model what was happening in nearby Golden Gate Park. The major difference was what happened after that, Ehrlich said.

The plan to cover the grassy, sand-duned heights with a forest was born in 1883. The idea, the brainchild of Maj. William A. Jones, had a threefold purpose. He wanted to create windbreaks, distinguish the Presidio from The City and make the military outpost monumental.

"The main idea is, to crown the ridges, border the boundary fences, and cover the areas of sand and marsh waste with a forest that will generally seem continuous, and thus appear immensely larger than it really is," noted the Plan for the Cultivation of Trees upon the Presidio Reservation in 1886.

It went on to say, "In order to make the contrast from the city seem as great as possible, and indirectly accentuate the idea of the power of the Government, I have surrounded all the entrances with dense masses of wood," Jones wrote.

Last, and perhaps most fatefully, while Jones indicated that the planting should not be haphazard, he wrote: "I would strongly recommend that all pruning of trees on this Reservation be forbidden. ... Nature can produce stronger and better looking trees than the average gardener."

The Army then went about its business, planting eucalyptus, Monterey cypress and pine.


When Ehrlich came to the Presidio and wrote up a plan of action in 2001, disease was attacking many of the pines, the forest floor was covered with debris and there was little life below the canopy.

Any plan to manage the forest had to juggle the historic designation that mandated maintaining the tree stands planted by the Army with spearheading regeneration of native species, among other things.

Since then, the forest has been nursed back to health through trimming and replanting. It has even attracted a wider array of bird species, said Ehrlich, and the forest has trees of varying ages rather than a lot of 120-year-old trees.

click to enlarge The forest in the Presidio of San Francisco has been nursed back to health over the last decade after many years of neglect. - MIKE KOOZMIN/THE S.F. EXAMINER
  • Mike Koozmin/The S.F. Examiner
  • The forest in the Presidio of San Francisco has been nursed back to health over the last decade after many years of neglect.

"It's a work of art; it's actually an artifact," he said of the man-made forest.

Part of such work has to include dealing with the eucalyptus, which Ehrlich said has unfairly been attacked.

Indeed, Jared Farmer, author of the 2013 book "Trees in Paradise: A California History," wrote in a recent article that the myth of the eucalyptus as dangerous and rapaciously invasive is overblown.

Many of the problems associated with stands of the trees planted more than a century ago are about mismanagement rather than any inherent danger. They were planted and then abandoned and not tended, which is detrimental to any forest's health. Additionally, Farmer said the tree is not nearly as invasive as other species, such as scotch broom.

The best approach to dealing with eucalyptus is a balanced one, wrote Farmer. If it's better to thin them rather than remove them, so be it, he wrote. In other locales, the trees can be replaced with fewer quick-growing species or native trees.


On a blustery day in early February on a Presidio hill overlooking the ocean, Ehrlich dug a small hole in the wet dirt so he could plant a Wallangarra tree sapling. It's one of the numerous eucalyptus species he has been planting in an experimental nursery.

As the blue gum forest ages, the plan is to replace the tree with another species of eucalyptus, one that looks much the same but grows and reproduces less rapidly. With the aid of Matt Ritter, a eucalyptus specialist at Cal Poly-San Luis Obispo, Ehrlich and his team have planted a small patch of eucalyptus species such as spotted gum and mountain gum.

Whichever eucalyptus tree is chosen, there's no doubt someone will have something to say -- unless, that is, they don't notice the difference.

About The Author

Jonah Owen Lamb

Jonah Owen Lamb

Born and raised on a houseboat in Sausalito, Lamb has written for newspapers in New York City, Utah and the San Joaquin Valley. He was most recently an editor at the San Luis Obispo Tribune for nearly three years. He has written for The S.F. Examiner since 2013 and covers criminal justice and planning.
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