SAN BRUNO MOUNTAIN DUNES
The Dune Defenders
In May of 2016, San Bruno Mountain Watch began the first large scale community-based ecological restoration initiative on the San Bruno Mountain Dunes—the San Bruno Mountain “Dune Defenders.”
From May 2016 through December 2019, over 2300 hours of restoration work were contributed by volunteers focused on the removal of invasive species like ice plant (Carpobrotus edulis) and crown daisy (Glebionis coronaria) as well as revegetation with locally-sourced native dune flora grown at San Bruno Mountain Watch's Mission Blue Nursery.
Approximately 2,250 square meters, or .56 acres, of ice plant have been removed in priority areas adjoining patches of the endangered San Francisco lessingia.
Planting within the restoration sites of the Dune Defenders, beginning in 2018, has led to the installation of more than 2000 dune plants across six planting areas.
The involvement of local students has been wonderful. The majority of the restoration efforts have happened as part of school field trips with Susan B. Anthony Elementary School, John F. Kennedy Elementary School, Westborough Middle School, Jefferson High School, Skyline College, and other groups, such as Scouts.
To accompany the restoration efforts, San Bruno Mountain Watch developed a curriculum to interpret the natural and cultural history of the San Bruno Mountain Dunes, receiving support from Measure K through District 5 Supervisor David J. Canepa as well as the San Mateo County Parks Foundation.
Recovering an Endangered Wildflower: The San Francisco Lessingia
In 2020, San Bruno Mountain Watch submitted a grant application to the US Fish and Wildlife Service, proposing to:
Expand the San Bruno Mountain Dune Defenders initiative to increase removal of invasive, non-native plants like ice plant (Carpobrotus edulis) in San Francisco lessingia habitat.
Carry out a restoration ecology experiment comparing methods of establishing new San Francisco lessingia populations. This experiment will help inform future expansion efforts on San Bruno Mountain.
Our grant application was awarded and will provide $20,000 of funding over a two-year period.
About the Dunes
The San Bruno Mountain Dunes, on the lower slopes of Reservoir Hill, loom above the houses on Bonnie Street. These are the remaining remnants of truly ancient dunes that were formed from 80,000 to 125,000 years ago as part of the Pleistocene Colma Formation. This deposition occurred during an interglacial period when the sea level was higher than today. This higher water level from melted glaciers made the northern San Francisco Peninsula an island - separated from the southern peninsula by a narrow stretch of water connecting the ocean to the bay.
When ocean waters reached the base of an ancient San Bruno Mountain, the deposit of material from several environments, over thousands of years, created the sands of the Colma Formation. Contributions from shallow tidal lagoons and silt from valley slopes gave this sand more soil-like properties and its characteristic iron-stained brownish coloring, contrasted to the gray sands of the coastal dunes. The unique sand of the Daly City Dunes now hosts a rare inland dune plant community