Notes from the Field: A Weed by Any Other Name

Invasive species like mustard threaten the health of the Bay.

It was a hot Saturday morning and my fellow field staff Jon and I were busy preparing for a full public program on Cinco de Mayo.  As we drove out onto the levee at Eden Landing Ecological Preserve we notice how well all of the California native plants were doing.  “Wow! Look at that Marsh Gumplant!”, I exclaimed with proud amazement.  With a little tender love and care from the many volunteers who helped sow and grow these wonderfully important plants, we were able to plant over 36,000 plants all around the Bay this year.

Spring has sprung here in the San Francisco Bay Area, reminding us at Save The Bay that with the hot weather and sun comes a new season for restoration. It’s Weeding Season!  Not only are our native plants blooming but so are a few plants that are non-native and in many cases invasive the tidal salt marsh.

As I begin to explain the restoration project to the group of eager volunteers, questions begin to pop up about why we are killing these plants.  Often I hear things like “These plants look nice”, “Where and how did these plants get here?”, and “Don’t animals use these invasive plants as habitat?”

Non-native invasive plants come from somewhere else because of human activity:

“When plants that evolved in one region of the globe are moved by humans to another region, a few of them flourish, crowding out native vegetation and the wildlife that feeds on it… These invasive plants have a competitive advantage because they are no longer controlled by their natural predators, and can quickly spread out of control.”  (California Invasive Plant Council)

The tidal salt marshes that ring the Bay are a prime candidate for non-native species.  All of the sites have changed significantly over the past 200 years.  As soon as humans began migrating here in large numbers, we began to drastically alter the salt marsh landscape.  Levees and dikes were created to drain the marshes for agriculture.  Cities were built and harbors were dredged in our marshes.  These interactions greatly affected the way the salt marshes functioned and brought loads of non-native invasive plants to the area.

Volunteers bask in their accomplishment of ridding Eden Landing Ecological Preserve of a mountain of invasive mustard plants.

Many of these plants are a common sight in the supermarket, such as fennel, mustard, radish, and oats.  They were first brought here by farmers looking to sow their crops on the land created when the salt marshes were drained.  Many other plants came by ships coming to port and inadvertently brought exotic seeds with them.  Invasive plants can significantly degrade wildlife habitat and are the second-greatest threat to endangered species, after habitat destruction.

As I explain these facts to the volunteers, they begin to get the big picture of our restoration process.

That Saturday morning the levees were covered in a thick wall of mustard.  But, by the end of the program everyone one of us felt a sense of accomplishment.  The wall of mustard threatening to spread its seed across our newly installed native plants was no more. Now the volunteers stood on what they affectionately dubbed “Mustard Mountain” all ready to be composted!

Come learn more about invasive plants. Volunteer during weeding season!