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Projects

Invasive Species Control

Slender False Brome (Brachypodium sylvaticum)
(Photo by False Broom Working Group)

An invasive species is a plant or animal species that is not native to the local ecosystem, takes over large areas, and reduces biodiversity in ways that often cause economic or environmental harm. The District removes invasive species from its preserves whenever possible.

The District follows a strategic plan when dealing with invasive species. When weedy plant species are located, their potential for becoming invasive at that location is evaluated. Of particular concern are invasive plants that will threaten rare native species or are likely to spread rapidly or cover large areas. A new sighting is added to a priority-based list for work by District staff, volunteers or contractors. District staff researches the best methods to control an invasive species using an integrated pest control approach, and makes certain to return to a site as many times as necessary in subsequent years to first contain the spread of the invasive plant and then eradicate it completely from that site. Regeneration of native plants is encouraged at the control site, or native plants are seeded or planted.

Feral Pigs

Since 2000, the District has been trapping feral pigs in the South Skyline and Sierra Azul regions. Feral pigs root up hillsides with their snouts, disturb plants, cause erosion, dig up wetlands, and eat acorns and other food sources so that less food is available to native wildlife. The trapping program, conducted in coordination with surrounding landowners and park districts, has greatly reduced the population of and damage caused by feral pigs.

Slender False Brome

A new and potentially destructive invasive species, slender false brome (Brachypodium sylvaticum), has been found in the Woodside area, including Thornewood Open Space Preserve. A perennial bunch grass originally from Europe, Asia, and North Africa, it is capable of achieving over 90% ground cover, inhibiting the growth of tree seedlings, and completely replacing native vegetation.

In Oregon, this invasive grass has spread to over 10,000 acres and has become a major resource management problem. Slender false brome was identified in Woodside in January 2004. This area is the only known location of the weed in California. It is important that the problem is taken care of quickly before it spreads and becomes unmanageable.

Currently, the District is conducting a public outreach campaign to educate private property owners and map the extent of the infestation. For more information, please visit the District Slender False Brome page.

Sudden Oak Death

Sudden Oak Death (SOD) is a forest disease caused by the fungus-like pathogen Phytophthora ramorum. The pathogen has caused the widespread dieback of some oak species and other plants commonly found in oak forests in Northern and Central California, including some District preserves. The pathogen causes cankers to grow on the leaves or wood of infected plants. Consequently, other pest organisms like fungi and bark beetles can eventually kill an infected tree. How the pathogen spreads is currently unknown, but it appears to be associated with moist winds, especially around California bay trees. It may also be spread by moving infected vegetation and soil, including material accidentally carried by shoes and tires.

In 2005, the District committed $350,000 over 10 years to find ways to prevent and treat Sudden Oak Death by working to identify resistant trees, prevent infection of heritage trees, and participate in collaborative research.  In 2006, the District began working closely with the California Oak Mortality Task Force to achieve these goals. Most recently (2008), the District partnered with scientists on a new research project aimed at preventing the infection of oak and tanoak trees with the plant disease Sudden Oak Death.

The combined results of all these studies will help the District prevent the spread of Sudden Oak Death for the safety of its visitors, health of the environment, and protection of California’s trees.

In the meantime, District staff continues to monitor the preserves for symptoms of Sudden Oak Death and to work with representatives from the Oak Mortality Task Force to stay abreast of the latest science and news regarding the spread and control of the pathogen. The District follows “clean practices” when working in Sudden Oak Death areas to control its spread into new areas. Closures of certain trails during the rainy season may also assist in controlling its spread.

To prevent the unintentional spread of Sudden Oak Death (remove soil and vegetation), educational materials and signs are posted at open space preserves with high-risk areas for Sudden Oak Death to encourage visitors to stay on trails and to clean their shoes, pet’s paws, and tires before leaving the preserve. Please take note of these signs when visiting District preserves.

For more information, visit the Oak Mortality Task Force.

  Current Projects

Slender False Brome Eradication

Wildland Fire Management

Fighting Invasive Weeds Through Prescribed Burns

Conservation Grazing

Sudden Oak Death Research


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