January 14, 2005

Presidio Maintains Its Role as Battle Site, This Time Over Nature

By Erica Gies
Special to the Neighborhood Newswire

Managers are striking a dynamic balance in the Presidio, not just between its development and its natural setting, but between how much of it’s natural setting will be historic, such as the Monterey Cyprus planted by the army, and how much will be, like the coastal live oak, truly indigenous. These are competing mandates -- preserving a centuries-old military past while simultaneously protecting and restoring an even older indigenous ecosystem – that have managers juggling historic and native flora.

"In many ways, natural parks are museums preserving natural resources and keeping them for future generations," says Betty Young, Golden Gate National Recreation Area (GGNRA) director of nurseries, which grows native plants for Presidio restoration projects. "The mission of the Park Service is to preserve natural and cultural resources. The historic forest on the Presidio is a cultural resource. Those two goals, preserving the natural and the cultural, have to somehow work together."

Perhaps no one understands this balancing act better than Terri Thomas, director of park resources for the Presidio Trust, a group that manages the park along with GGNRA and the National Park Service. She's working to restore both the Presidio's native plant communities, including many endangered species, as well as protect the aging nonnative trees planted by the U.S. Army.

"The Presidio had diverse native vegetation and still does," Thomas says. "It's very valuable to restore remnants of this ancient landscape, very fragile remnants that include endangered species, rare species, rare habitats."

But the nonnative trees also provide a habitat for a number of different bird species, including red-shouldered, red-tailed, and Cooper’s hawks; woodpeckers; and even great horned owls.
Paul Ehrlich, the Presidio Trust’s forestry manager, is initiating the replacement of the aging historic forest, a program that will take place over the next 65 years. "This slow and selective approach will create an uneven-aged forest that will have multiple canopy levels unlike the present forest with its one canopy level," says Ehrlich. "The initial forest was planted very quickly by the army in the late nineteenth and early twentieth centuries. The uneven-aged forest that is being created now will provide even more wildlife habitat than the present declining forest because it will have more structural diversity."

The Army planted the nonnative eucalyptus, Monterey pine, and Monterey cypress forests to create windbreaks, establish boundaries between different areas of the fort and to make the land more appealing to the soldiers stationed there. Many San Franciscans still find the trees attractive - and emblematic of the Presidio.

However, these nonnative trees also inhibit the growth of endangered plants protected by the Endangered Species Act. In some park areas, managers are considering substituting the historic species with older, indigenous vegetation.

Prior to being settled by European explorers, most of the Presidio - and in fact, most of San Francisco - was sand dunes, populated with low-growing plants. These species adapted to thrive in full sunlight and do not do well under the shady canopies of the nonnative trees.
In consultation with other stakeholders, including the U.S. Fish & Wildlife Service, California Native Plant Society (CNPS) and the Audubon Society, Thomas and her team drew up a map of zones to be managed differently.

For example, there are several stands of trees in rows along streets that are considered to be historically significant. Because these trees are near buildings and were planted in a linear, unnatural fashion, they have a very specific look. When these trees die, they will be replaced with the same species in the same rows.

In other areas, where the Army planted trees more haphazardly, "the value of the forest is probably as a dark green backdrop to other things," Thomas said. "In those cases, there's more flexibility. You can have multiple strata of trees that's better wildlife habitat."
One possibility is a different type of eucalyptus that doesn't have as dense a shade canopy and leaf litter, like the current blue gums.

Another species under consideration is the coastal live oak, which is native to the Presidio. It was originally found only along the riparian corridors bordering Lobos Creek and Mountain Lake. Thomas and her crew have planted test patches of the oak to determine how it will do in other areas and how other native plants will fare under its canopy.

Other native-to-the-Presidio trees that might be more widely planted if test patches go well include California buckeye, coffee berry and toyon, which are small, grow well under other trees and have berries wildlife finds tasty.

Another zone that provides a great deal of potential "new" area for natives has not been designated historic because the Army did not value it: dumps.

"The Army thought that every canyon over a bluff was a place to throw garbage," Young says. "They thought they'd just cap them and plant grass. The Trust is actually removing the landfills and restoring those areas back to the habitat that was there before. And that's a significant restoration because those sites were large."

According to Thomas, "We're doing a dramatic one right now on the coastal bluff. We took out the landfill and now it looks like the Grand Canyon. These places were just nothing and we're turning them into pretty cool stuff. The first one we did was a parking lot and now it's got three different kinds of habitat on it."

Pinky Kushner, who's head of the Sierra Club's open space committee, was pleased with the results.

"When one walks along the walkway, the place hums with life: insects and birds and butterflies of all sorts," she says.

Landfill cleanup in the Presidio is overseen by the California Department of Toxic Substances Control for compliance with the state’s hazardous substances cleanup law, which is similar to the federal Superfund law. Although capping material where it lies is being considered in a few instances, most Presidio landfills are excavated, tested, and taken to appropriate environmental remediation sites. By the time plant ecologists and volunteers kneel down in the dirt to plant, the soil is clean.

In spite of the Trust's success in increasing native habitat, some stakeholders are frustrated by the restrictions imposed by the need for historic forest preservation.

Peter Brastow, rare plants co-chair for CNPS's Yerba Buena Chapter, says that his group applauds the Trust's work on ecological restoration. However, he's concerned about how the historical mandate will impact the ongoing success of native plants and animals.

"The historic forest is a planted forest 120 years old. The indigenous animals and plants are thousands, maybe millions of years old," Brastow says. "The Presidio is not just something that happened. It's something that's going to happen in the future. What's truly logical in terms of managing land for the future? Keeping part of this forest frozen in time or adapting to the idea that this thing has to evolve into the future? The most sustainable effort is to bring back the processes that sustain biological life so they'll ultimately work for themselves."

Some of the Presidio's native critters would benefit from more native habitat, including the monarch butterfly, California slender salamander and gray fox.

California quail used to flourish among the silver dune lupine, mock heather and coyote bush. Due partially to the increase in nonnative plants, the population declined significantly in the '80s, and today there are only 20 left in the Presidio.

According to Alan Hopkins, director of the Save the Quail campaign for the Golden Gate Audubon Society, a lot of nonnative plant species have taken over, including ice plant, various ivy species and all of the ground cover.

"There are a lot more predators than before: cats, raccoons, ravens, crows, jays. They are getting squeezed at both ends," he says.

Hopkins and others at the Audubon Society took their concerns to the Presidio Trust, and managers there prioritized quail habitat for native plant restoration.

"Native plant restoration is keeping them going and keeping them alive," Hopkins says.
In 100 years, Thomas would hope to see "native diversity maximized, wildlife enjoying the mosaic of habitats, creeks restored, and the public enjoying and being educated by that diversity and abundance."

Erica Gies is a writer with the Neighborhood Environmental Newswire.