Invasive Plants at Bolsa Chica
Bolsa Chica Stewards and the Battle of the Weeds
What is an invasive species?
An invasive species is a non-native species that aggressively takes over wild open spaces from native species. The invader gobbles up food, space, water and other resources that native species rely on to survive. In some cases they even directly prey on or eat the native species! Oftentimes, the invasive species is so successful at eliminating the competition from native plants that it creates a monoculture. This is horrible for biodiversity, soil health and stability, fire resistance, and more.
Not all non-native species are invasive, and often times as restorationists, we have to be selective on which species to remove and which species to ignore (for now). We also have to be cognizant of the fact that a lot of the time complete eradication of invasive species is unrealistic. Non-native species are constantly reintroduced into areas through foot traffic on shoes or clothes, ballast water from ships which bring seeds to the shoreline, and even natural ways like birds and wind. The hope is that by replacing the invasive species with native plants the balance will tip in favor of the restored habitat and the invasive species will no longer be the dominate plant.
Stewards vs. Invasive Plants
The Bolsa Chica Stewards have been battling weeds, aka. invasive species, here at Bolsa Chica for 3 decades. It started with wild mustard and a small group of people on the public side of the fence. Black mustard, short-pod mustard and the like, used to dominate the entire Lower Mesa. The mesa would be a blanket of yellow flowers in the spring and a bed of brown fire fueling sticks the rest of the year. Additionally, ripgut grass, oats, barley and other non-native grasses were also rampant. Slowly but surely, the community-based volunteer-driven habitat restoration work has replaced acres of invasive mustard, wild radish, and other invasive species with healthy sustainable Coastal Sage Scrub habitat.
Invasive Plant of the Year
Each year, we unofficially have an Invasive Species Plant, or Plants, of the Year. The 2026 Invasive Plants of the Year are Cheeseweed Mallow and Wild Radish. A species is crowned with this facetious title by being the dominate invasive species, and therefore the target species we have volunteers focus on. Most of the time this species grows to monstrous sizes and is widespread creating a dense mat of vegetation.
We never know which species is going to come out on top. There are many factors that impact the flora composition each year, but the most notable is rain. During rainy seasons, mustards, radishes, mallows, storkbills, even curlydock explode like the Hulk. During dry seasons, Russian thistles and iceplants annihilate the competition. The non-native grasses, most prolific being Ripgut grass, are a constant nuisance regardless of rain amount.
Weed Warriors of Today
The Bolsa Chica Stewards continue to get down and dirty (with our shovels) to tackle invasive species. After the offensive weeds are removed, we replace them with native plants grown in the Growing Space, our native plant nursery. When we remove the invasive plants we try to get them out by the roots before they go to seed. This takes coordinated timing, an army of volunteers, and dedicated leadership.
We want YOU to be a Bolsa Chica Steward Weed Warrior! Heed the call. Join us during our public volunteer days held the first Sunday and third Saturday of every month.
photos: Brenda Lee, E. Chin, Jodi Thorn
