Malibu Park Ecologist Battles Invading Weeds
In the centuries-old scuffle over Malibu Creek State Park in the Santa Monica Mountains, stubborn outsiders like milk thistle and black mustard have racked up a long winning streak.
Theoe nonnative plants have nearly conquered the northeast corner of the park, driving out the indigenous grasses that once carpeted valley floors.
But park ecologist Suzanne Goode wants to even the score. Like a coach plotting a fourth-quarter comeback, Goode aims to tire out her opponents and then, in their weakest moment, clobber them into submission.
In their place, she envisions a valley oak savanna filled with kangaroo rats, rattlesnakes, coyotes, foxes and quail, a rich display of biodiversity amid a backdrop of native grasses swaying in the breeze along Las Virgenes Road.
“It’s really the quintessential California landscape,” Goode said. “This is what we are going to try to reproduce here, instead of just a weed field.”
All spring, park workers have been planting shoots of purple needlegrass, a native plant, on a 2-acre plot just south of Lost Hills Road. The slender tufts stand out like a pale green island in a yellow sea of mustard.
Ecologists suspect that foreign plants were introduced to California centuries ago by Europeans. Now, they are trying to turn back the clock, weakening the tenacious thistle, mustard and other imports with fire and herbicide before reintroducing the indigenous plants.
For three years, Goode has prescribed fire as the cure for the invasive weeds, which suck up the water and blot out the sun that native plants need. In the last controlled burn here in 1998, firefighters methodically torched 80 acres.
The fire adds nutrients to the soil that stimulate the thistle seeds to germinate, Goode said. Instead of lurking underground for 10 years, the seeds send up more thistles. But after several years of burning, the seeds are pretty much spent.
Herbicide and plain, old-fashioned yanking take care of any thistle that dares to show its leafy head after such a beating. Goode scours the sunbaked ground near the baby needlegrass, looking for interlopers.
“There’s a milk thistle right there,” she says, pointing at a small, bushy clump. “We need to kill it.”
A few yards away, a trio of park workers is planting needlegrass, one tiny bunch at a time.
They’ve worked out a system: Angel Limon jabs the earth with a spear-like pole, making a hole. Then his son, Ruben, slips the plant’s roots inside and pats down the dirt. Kim Kaufman follows with a watering can, giving each grassy wisp a drink.
“They look pretty good,” Ruben says. “I feel real proud.”
Irrigation pipes snake through the grass, pumping in reclaimed water from the nearby Tapia sewage treatment plant. The facility is prohibited from discharging treated water into Malibu Creek during the dry summer months, but the park reuses the water to lengthen its planting season.
The park workers have also planted a few valley oaks. Someday, Ruben says, when his 6-year-old daughter is grown, he hopes she’ll visit this spot and rest in the shade of a towering oak that he planted here as a seedling.
At the moment, though, the oak trees look more like 2-foot twigs with a few miniature leaves. And at the northern end of the field, mustard is creeping back into the area reserved for the fledgling natives.
After much searching, Ruben finally spots a spray of needlegrass amid the ever-encroaching weeds. “We call it the weed wars,” Ruben says. “Every time we get rid of one, some other weed grows back.”
