Controlling Euphorbia terracina along Coastal Areas of LA County

Los Angeles County Weed Management Area members coordinated their efforts to treat outlying populations of Euphorbia terracina. Infestations in the United States are currently limited to Los Angeles and Ventura counties as well as infestations in Pennsylvania. This species has numerous ecological impacts including formation of dense monocultures, vigorous resprouting and site dominance following fire, massive seed production and rapid dispersal. In addition, it has toxic sap that causes temporary blindness and a poison oak-like skin rash in susceptible individuals. Limiting the spread of this species will protect oak woodland, grassland, coastal sage scrub, and riparian communities from the ecological damage caused by this species. Preliminary studies of Euphorbia terracina invaded sites show 100% cover of Euphorbia terracina, no sign of insect or animal browsing, and no sign of any bird activity in E. terracina areas. The project hopes to prevent further spread by eradicating populations at the leading edges of the infestation.

Solstice Canyon Project
Principal: Christy Brigham (Santa Monica Mts. Santa Monica Mountains National Recreation Area)

The Solstice Canyon site is owned by the National Park Service. Solstice Canyon is an important and rare ecological resource both within the Santa Monica Mountains National Recreation Area and the Los Angeles Basin as a whole. This canyon contains an intact, well-developed riparian corridor surrounding a perennial stream with uplands of coastal sage scrub. These ecological communities are rare in the Santa Monica Mountains; many areas that were coastal sage scrub or riparian vegetation have been developed or damaged by past or present human activities. Although Solstice Canyon represents only 0.3% of the
Santa Monica Mountains National Recreation Area by area, it contains 23% of native plant species found in the mountains, indicating that it is a local center of plant diversity. Many of the species found in the canyon are rare within the mountains including white alder and Plummer’s baccharis. Solstice creek was also home to the federally endangered southern California steelhead trout and efforts are under way to restore steelhead to the creek. Euphorbia control work is being conducted in Solstice Canyon using funds from Proposition 12.

All Euphorbia terracina populations in Solstice Canyon will be treated with a combination of handpulling and herbicide application between January 2007 and January 2008. Control methods and timing will be based on extensive field experience by NPS treating this species at this and other sites. All treated areas are being replanted with native coastal sage scrub plants between January 2008 and January 2009. This portion of the project is funded by Proposition 12 funds given to NPS and is considered an in-kind contribution.

Palos Verdes Peninsula Project
Principal: Andrea Vona (Palos Verdes Peninsula Land Conservancy)

The Palos Verdes Peninsula is an important coastal ecological resource for the Los Angeles Region. It supports several habitat types such as coastal sage scrub, coastal bluff scrub, coastal cactus scrub, riparian habitat, and grasslands. The Peninsula is home to the El Segundo blue butterfly (Euphilotes battoides allyni) and the Palos Verdes blue butterfly (Glaucopsyche lygdamus palosverdesensis), both of which are endangered species. Over 80 pairs of California gnatcatchers (Polioptila californica californica) reside on the Peninsula, which represents the largest population of this threatened species in Los Angeles County. The flora of the Peninsula is also special, as there are 7 rare or endangered species and 7 species of limited distribution as designated by the California Native Plant Society.

For this project, the PVPLC is working to eradicate and control infestations of Euphorbia terracina occurring throughout the south side of the Palos Verdes Peninsula for the 2007 and 2008 calendar year. This invasive plant occurs to some extent in almost all open space areas on the Peninsula as well as in residential neighborhoods and a large area surrounding Marymount College. Removals are proposed from open space areas under the management of the Palos Verdes Peninsula Land Conservancy such as White Point Nature Preserve, George F Canyon Nature Preserve, and the Portuguese Bend Nature Preserve. LA County Ag will work toward eradication of Euphorbia terracina from Deane Dana County Park. All populations are being treated with a combination of hand pulling and herbicide treatment. The PVPLC is also working to obtain permission to treat invasions on areas not under their management. These areas include individual residential properties, and open spaces on the campus of Marymount College. The Land Conservancy has had discussions with the President of the college and some homeowners, and they have expressed a willingness to cooperate with the effort.
High-Value Site Protection Via Island-Wide Species’ Eradication
Principal: John Knapp (Catalina Island Conservancy)

After habitat loss, invasive species have been identified as the second greatest threat to the preservation of biodiversity worldwide and are likely to be the greatest contributor to species extinctions in island ecosystems. Catalina Island (Catalina) is no exception, invasive plant species now threaten the Island's native flora and fauna (including 39 endemic taxa) and it's unique habitats. The Channel Islands archipelago, which includes Catalina, has been described as the Galapagos of the Northern Hemisphere due to the high rate of endemism and rare taxa. Nearly 100 Natural Heritage species, as well as four Federal Trust habitats are impacted to differing degrees by invasive plants on Catalina. Catalina is home to six flora and fauna species that are listed as either endangered or threatened by the State of California, of which four have been identified in the Federal Register as being threatened with extinction by invasive plants.
Vinca major

This project is focused on completely eradicating all known populations of yellow starthistle (Centaurea solstitialis), Veldt grass (Ehrharta calycina), saltcedar (Tamarix ramosissima), and periwinkle (Vinca major) from Conservancy property (42,000 acres). Catalina's isolation from the mainland will provide an effective natural barrier to future dispersal of new invaders, and the benefits gained through this project will be relatively easy to maintain through inspection and monitoring of seed banks of eradicated populations and defined entry points. Once each species is eradicated from the island, it will be extremely unlikely that they will successfully disperse back to Catalina. Although periwinkle has the potential to reinvade Catalina due to its use in the horticulture trade, it is however banned from landscaping on all Conservancy properties. Species require a different suite of control techniques based on its physiology, location, and abundance. The least disruptive and most cost effective control methods are being utilized to ensure both personnel and environmental safety as well as control success. Physical control methods, such as hand-pulling will be used on smaller populations of some species. Mechanical control methods utilize a wide array of hand and power tools, including "weed wrenches" hoes, and power brush cutters. Herbicides will be used on this project when physical or mechanical techniques alone are not effective.
A large portion of the funding received by our WMA goes toward on-the-ground control and removal projects. A synopsis of those projects currently underway are presented here.

For further information, please contact the project's principal investigator.
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