March 10, 1994
Contact: Alisa Zapp or Robert Irion (408/459-2495)
SCRUBBING OUT POISON HEMLOCK HELPS RESTORE COASTAL SCRUB
FOR IMMEDIATE RELEASE
SANTA CRUZ, CA--Its flowers bloom in dainty white clusters, but smell like rodent urine. Its soft leaves curve like delicate ferns, but contain a poison deadly to animals, birds, insects, and neighboring plants. For decades, the invasive poison hemlock, legendary killer of Socrates, has squeezed out native plants and reduced the habitat of native species on the central California coast.
In the Younger Lagoon Natural Reserve, in the southwest corner of Santa Cruz, poison hemlock covers swatches of land with a blanket of toxic leaves. But near one edge of the reserve, the scene is different. Here, carved out of knee-high hemlock, an eighth of an acre of bare ground is punctuated with clumps of native plants. This bit of land demonstrates the success of an ambitious project in the reserve: to eradicate poison hemlock and restore native plants and natural habitats.
Coordinated by the University of California's Natural Reserve System and aided by the UC Santa Cruz Arboretum, the project gives UCSC students invaluable field experience and establishes, for the first time, the techniques necessary to replace poison hemlock with native plants in this locale.
"The strength of this project is that it is not a single-focus project," says Maggie Fusari, coordinator of the Natural Reserve System for UCSC. "If you're a student, the most important aspect is the educational opportunity. If you own land in the area and need restoration advice, it's the applied research. And if you are interested in the reserve itself, it's in improving the biodiversity of the reserve and the character of the natural communities."
The project's goal is to restore native scrub to the strips of land most thickly covered with poison hemlock, an area totaling about five acres in the twenty-acre reserve.
Sandwiched between UCSC's Long Marine Laboratory and a brussels-sprout farm, Younger Lagoon was set aside in 1987 as part of the UC Natural Reserve System, a collection of 32 ecologically or biologically unique sites in California reserved as teaching and research laboratories. Younger Lagoon contains scattered remnants of native coastal scrub communities: wind-twisted shrubs, low- lying herbs, grasses, and flowering plants. The scrub communities provide homes for dozens of bird species, small mammals, and predators, including bobcats, foxes, and coyotes. However, these habitats steadily disappear as poison hemlock chokes out native plant communities.
Poison hemlock was originally imported as a decorative garden plant from the British Isles in the late 1800s. It gained a foothold at Younger Lagoon when irrigation and fertilization on neighboring farmland and construction of Long Marine Lab further disrupted native plant communities. Found in Mediterranean climates throughout the world, the weed is toxic to most plant species, apparently provides no food for wildlife, no nesting area for birds, and much less protection against soil erosion than native plants. "It's like a green oil spill--tremendously destructive," says Grey (his full name), steward of the reserve and supervisor of the restoration project.
The first step in the restoration process is to hand cut or pull up poison hemlock in the late spring, just before its seeds mature. Each hemlock plant produces a thousand seeds, which are dispersed by the wind or drop to the ground. To prevent seeds lodged in the soil from germinating, students spread a four-inch-thick layer of straw mulch over the weeded ground. The students then set up miniature scrub communities by planting clusters of native plants: coyote brush, buckwheat, tree lupine, purple needle grass, and other hardy species.
Success of the restoration project, which began two years ago, has exceeded expectations. Lupine planted last year has grown four feet tall and equally wide. "The plants we put in have had a great survival rate; there's no way poison hemlock will take over when they're this big," says Grey.
Critical to the project is the support of the Arboretum, which provides space and horticultural expertise to grow the native species from seeds or cuttings until they are planted in the reserve.
Work at the reserve provides students with a senior thesis project or internship credit. Five undergraduate students majoring in biology or environmental studies have been involved in the restoration project. Three of these are finishing up their theses and two new students plan to join the project in the spring or summer.
"The program is uniquely suited to the Santa Cruz educational philosophy of having students do senior thesis work as a transition to their professional lives," says Fusari. "These students are interested in careers in restoration ecology and horticulture."
Restoration ecology is a burgeoning field as more businesses, developers, and private citizens become interested in recovering native vegetation. But currently there are no standard techniques for chemical-free restoration of native plant communities. "There's a very pivotal role for this research," Fusari says. "If we show people what works, then more people will be willing to try it." She and Grey hope to submit the results of the Younger Lagoon project to a scientific journal in about a year. Workers in different locales may have to modify the techniques used at Younger Lagoon to best suit the unique combination of sun, wind, and other environmental conditions in their regions.
Fusari and Grey estimate that they could restore native scrub to the five acres in the reserve in five years with sufficient funding and three or four full-time workers. Other projects at the reserve include analyzing the salinity of the soil, mitigating the effects of the neighboring farm, and cataloging bird and animal species.
Editor's note: You may reach Fusari and Grey at (408) 459-4971.