Bay Nature’s July-Sept 2010 issue provides wonderful background information on the Oakland Hills Serpentine Prairie site.  Conservation chair Laura Baker is quoted twice in the article.  Here’s the full article.

Last of the Serpentine Prairie

Oakland's Serpentine Prairie

The serpentine prairie off Skyline Boulevard in Oakland has undergone substantial restoration. Photo by Wilde Legard, East Bay Regional Park District.

High in the Oakland hills, at the intersection of Skyline Boulevard and Crestmont Drive, lies a remnant of one of the state’s most botanically important habitats. In spring, the serpentine prairie in this corner of Redwood Regional Park erupts into spectacular native wildflower displays. Goldfields form a yellow carpet, while the rich buttery orange of California poppies stands out against the emerald grasses, themselves a mix of natives and invasive European species.

Serpentine grassland once covered hundreds of acres of the Oakland Hills, stretching west from the ridgeline down toward the flatlands. Today, the 46-acre parcel “might be the last extent of the original ecosystem” in Oakland, says Stuart Weiss.

Poor in nutrients and containing heavy metals, serpentine soils are inhospitable to most plants. However, many native bunchgrasses and wildflowers have evolved to make a living on these impoverished soils. Indeed, one tenth of California’s endemic plants are serpentine soil specialists.

Among the serpentine plant species found here is the federally endangered Presidio clarkia, which lives only here and in San Francisco’s Presidio. In late spring, it produces four-petaled flowers forming a delicate cup of fuchsia pink with a center saturated in deep red.

Presidio Clarkia

The endangered Presidio clarkia survives only at the Presidio in San Francisco and on grassland in the Oakland Hills. Photo by Lech Naumovich.

The Presidio clarkia’s persistence here is a minor miracle. Starting in the 1950s, the land was used as a horse pasture and field course with obstacles and jumps. In the 1960s–before native habitats were valued by most land agencies–the district planted dozens of Monterey pines and acacias. More recently, the prairie became a favorite place for dog owners to let their pooches romp off leash.

So many humans, dogs, and horses came here that some parts of the meadow were compacted into bare earth. Fallen needles from the pines built up a thick layer of humus, and dog waste formed unnatural islands of nitrogen enrichment. The trees themselves captured fog and delivered extra water to the soil. Even car exhaust delivers nitrogen to otherwise nitrogen-poor serpentine prairies.

“I remember working out there in the ’70s and ’80s, but I hadn’t seen the serpentine prairie in a long time,” says the district’s Wildland Vegetation Program Manager David Amme. “One day I went out there, and I was totally blown away. It was only a shell of what it used to be.”

Concerned neighbors circulated a petition and turned to the California Native Plant Society (CNPS) for help. Amme worked with local residents, conservation volunteers from CNPS’s East Bay chapter, and officials from the California Department of Fish and Game to come up with a plan to protect the clarkia and other prairie plants.

District botanist Wilde Legard and a colleague conducted an inventory of the existing clarkia population–not a simple task. They worked for three weeks to create GPS-based maps and estimate the numbers of individual plants. Amme then asked Weiss, who had worked with the clarkia at the Presidio, to develop a management plan. Weiss identified a number of ways to tilt conditions in the clarkia’s favor, ranging from removing trees to fencing certain areas to exclude dogs, horses, and people.

removing trees with crane

The park district used a crane to remove trees, to avoid disturbing wildflower seeds in the soil. District biologists hope the small Presidio clarkia population here will eventually spread over a larger area. Photo by Wilde Legard, East Bay Regional Park District.

The district held a series of public meetings to explain the plan, hear concerns, and adjust accordingly. The final plan should help the entire community of native plants, endangered or not. “It was the first time the district had put together a resource management plan focused directly on a botanical resource,” says Laura Baker, East Bay CNPS conservation chair.

Starting in summer 2009, trees on the eastern edge of the site were cut and lifted away with cranes to avoid disturbing any clarkia seeds. The acacia and pine duff was removed and the ground sowed with native grass seed collected on the site. A broad swath of the prairie was fenced, and signs were posted to explain the restoration. More nonnative trees and duff will be removed in the future. “The hope is that the clarkia population will expand into the area on its own,” Legard says, “but we are willing to reseed if necessary.”

Using experimental plots, Weiss is studying how the clarkia fares inside fences versus outside, in shade versus full sun, and with or without mowing and raking. “You learn what’s working and what’s not as you go.”

Changes to the site have been accepted by dog walkers and plant enthusiasts alike. “We held our breath to see if there would be a public outcry, but there was none,” Baker says. “It went from being something the district was not dealing with to a showcase of what could be done when a resource is managed appropriately.”