Mountains Restoration Trust (MRT), working with Los Angeles County Parks and Recreation, National Park Service, and California State Parks, undertakes restoration projects throughout the Santa Monica Mountains. One of these projects involves the preservation of biodiversity in the Cold Creek Watershed by bringing back the native fish – steelhead - and by eliminating non-native species such as the Arundo donax (giant cane).
Since 1984, MRT has focused on the preservation of the biodiversity of the Cold Creek Watershed. Cold Creek is a tributary of Malibu Creek and, like Malibu Creek, was a steelhead stream before the Rindge Dam blocked access to the upper reaches of Malibu Creek and its tributaries. Recognizing the reduced function of Malibu Creek as a steelhead stream and life support system for wildlife, MRT decided on a 10-year course of action.
“A number of federally or state-listed species depend on riparian zones in the Malibu Creek Watershed for all or portions of their life cycles; ten invertebrates, two fish, two amphibians, eight reptiles, twenty-three birds, six mammals, and five plants that are federally and/or state-listed as threatened, endangered, or candidate species may occur there.”
One of the most destructive forces to wildlands, natural resources, biodiversity and habitat is the invasion and dominance of non-native plant species. Non-natives alter the indigenous landscape by forming monocultures that suffocate all other plant species. We are all familiar with the bright colors of spring: the yellow of mustard and the bright green of grass. Unfortunately, these are some of the non-native plants that came from Europe with the early settlers. Coming from a mediterranean-type climate regime (wet winters and long hot summers), southern California was ideally suited to their survival. Many of these European plants had found ways through the millennium to survive, not only the summer drought, but the grazing of domestic sheep, goats and cattle. Our native plants had no defense against such massive land disturbance and domestic grazers. So, resource agencies throughout the state, nation and world are stepping in to give native plants a fighting chance.
MRT recognized that the wetland resources of lower Malibu Creek are faced with an extremely serious threat, the invasion of Arundo donax. This exotic plant is an aggressive, bamboo-like perennial grass that clogs streams and rivers and crowds out native plants. Arundo donax alters riparian canopy structure, food availability, fire regimes, sedimentation, and water purification capacity, greatly impacting wildlife. This project will continue to restore these wetlands by eradicating Arundo and allowing the infill of native plant species such as willows and sycamores.
The eradication program began in 2000 with funds from the National Park Service and a grant from Los Angeles County through the Habitat Conservation Fund to remove the giant cane from the lower 2.5-mile reach up to the Rindge Dame, the only reach of Malibu Creek accessible for steelhead trout spawning.
The project expanded to include the stream between the dam and the bridge on Las Virgenes/Malibu Canyon Road with a Proposition 12 grant from the Santa Monica Bay Restoration Commission funded by the California Coastal Conservancy. The project now totals 4.2 miles of stream and creek-side (riparian) vegetation.
A survey conducted by Sapphos Environmental after the completion of the 5-year project begun in 2000 determined the overall success of the program. “As a result of the 2006 surveys, it was determined that a 62-percent complete mortality rate was achieved with 99.4 percent of the patches displaying greater than 80 percent mortality. These results are outstanding for treatment of species as persistent as giant reed over a large area.2” However, some of the 219 clumps of giant cane were still growing. Arundo donax is a species where the term “almost dead” means that it will, in time, fully recover to create large clumps that push out native vegetation.
Therefore, MRT applied for and received another grant from the Santa Monica Bay Restoration Commission to continue the removal from the original 4.2 miles in addition to the 4.9 miles between the bridge on Las Virgenes/Malibu Canyon Road and the Malibou Lake dam.
The removal of giant cane (Arundo donax), from the riparian areas of Malibu Creek will immediately benefit the survival of the southern steelhead trout and the tidewater goby, state/federal listed species, by reducing the absorption of creek water by the giant cane. The results of scientific studies agree that Arundo donax reduces already scarce water resources in mediterranean-type climate regions such as southern California. The rate of evapotranspiration can vary radically depending on the size of the plant, the mass of its roots, water availability, and location in the riparian corridor. All studies conclude that giant cane uses a great deal more water (without providing beneficial habitat) than native vegetation like willows and poplars, but the estimate ranges from a 3% to 110%.
Other factors that keep giant cane from being on the “A” list of desirable riparian plants include little value as wildlife habitat, noxious chemicals in its leaves and stems repel insects and animals, clonal growth prevents native animals from moving through the canes, and natural river processes are negatively impacted by lowering groundwater table, decreasing surface water in streams, reducing and/or eliminating plant and animal biodiversity, and creating the potential for extremely hot fires.
The removal and/or control of non-native plant species benefits an area larger than the project site.
The Santa Monica Bay Restoration Commission approved the removal of Arundo donax finding that the removal of non-native species from the Santa Monica Bay watershed (including Malibu Creek sub-watershed) is integral to restoring the watershed to the maximum extent possible, and restoration of the watershed and its composite streams, tributaries, and native habitats is a primary component of the Bay Restoration Plan.
The work will resume when state bonds that fund grants are no longer frozen.