By Ariella Simke, Freelance Science Writer
WRA is contracted by the San Mateo County Parks Department to eradicate the highly invasive species Jubata grass (Cortaderia jubata) from the sheer cliffs along the coastal bluffs of the Devil’s Slide Trail in Pacifica, California. Jubata grass is a tall, feathery plant that has quickly spread since first introduced in the mid-19th century, and have proliferated so successfully that many people now consider their tufted plumage an iconic part of the rugged California coastline. In reality, the plant is extremely disruptive to the natural ecosystem. If left untouched, it will completely cover the cliffside, pushing out less robust native species that provide erosion control and important habitat for native wildlife. Closely related to Pampas grass in appearance, Jubata grass is more invasive because of its ability to self-pollinate. Each year the plant flowers, producing more than 100,000 seeds per stalk, making eradication efforts very challenging.
For the next three years, a team of WRA Landscape Restoration specialists, led by Rolland Mathers will work to eliminate the spread of this invasive plant so that this beautiful and ecologically-important ecosystem can return to its naturally balanced state. Nearly half of the bird species in North America visit the Devil’s Slide area, and nearly 20% of the flowering plant species in California can be found along the coastline (1). The exposed cliffs host a unique community of flora including: Gumplant (G. stricta, G. camporum, and G. hirsutula), California Sagebrush (Artemisia californica), California Phacelia (Phacelia californica), Seaside Daisy (Erigeron glaucus), and Lizardtail (Eriophyllum staechadifolium). These species do well with the varied types of soil, extreme slopes and changing moisture conditions of the area. When present, they create a healthy habitat for native insects and wildlife to prosper. In the plant world, groundspace is essential for access to nutrients, sunlight, and water. Because Jubata grass is so voluminous both above- and below ground, they take up so much space that native species can’t compete for the resources necessary for growth.
Jubata grass has spread like wildfire since the 1990s when removal efforts first began. In the absence of animals to eat these non-native plants, approved herbicides are the most effective method of control. Thriving in eroded and exposed landscapes, most of the plants being removed by WRA are located high on the sheer cliffs surrounding the trail. The only way to access these areas is through the use of ropes and harnesses. WRA staff rappel down the cliffs, gingerly stepping to avoid disturbing too many rocks, and spot-target each plant to destroy both the above- and below ground biomass. Spot-spraying avoids unnecessary exposure to non-target species, and a blue coloring is added to the herbicide so that the specialists can carefully control where the spray is administered. Because of the precarious nature of the task, field work is heavily dependent on weather conditions and requires extensive training. High winds and fog can obscure visibility and interfere with the targeted spraying. Luckily during the first field days, the WRA staff were blessed with clear skies and sunny 75-degree temperatures!
WRA Landscape Restoration specialists will return to these cliffs each year in early Fall to continue to suppress the invasive plant and make the area inviting for the recolonization of native species. Repeated application of the herbicide will eliminate the seed bank that exists in the area over time so that park visitors and wildlife can enjoy the restored native habitat once more.
Special thanks to Rolland Mathers and Dan Brubaker of WRA Landscape Restoration and the San Mateo County Parks Department for the opportunity to support this important regional work.