Onward and Upward: The Battle Against Invasive Limonium Continues

By Amanda Swanson, PhD, NBC Restoration Coordinator


The effort to remove Algerian sea lavender (ASL; Limonium ramosissimum) and European sea lavender (ESL; Limonium duriusculum) from the saltmarsh of Upper Newport Bay continues on. For several years, our dedicated volunteers have worked relentlessly removing these invasives to restore vital habitat for our endangered salt marsh bird’s beak and Belding’s savannah sparrow. In 2016, Newport Bay Conservancy (NBC) was granted a U.S. Fish and Wildlife Service (USFWS) grant to help fund restoration efforts, leading to the Wednesday morning ASL events that are held weekly. These events now host an amazing team of passionate volunteers who attend every single week. The dedicated leaders of this project have been Howard Cork, Don Millar, Dick Zembal and Mary Gartung.

Much of the time during the weekly events is spent pulling ASL by hand. But in areas where ASL is extremely dense, the most effective treatment has been solarization using black plastic tarping. Dense patches of ASL create thick mats that prevent native plants from growing and cause unsuitable nesting habitat for birds (see photo). The plastic tarping is secured on top of these ASL mats and is left for several months, generating temperatures high enough to kill the ASL beneath. Within weeks of removing the solarization tarping, growth of native pickleweed, saltwort, and jaumea is visible. As much of the plastic tarping can be seen from Back Bay Drive, many passers-by often mistake it for trash. However, this is an incredibly effective method for removing this invasive plant and is an important tool for restoring the critical saltmarsh habitat of Upper Newport Bay.

To build upon ongoing removal of ASL, NBC was recently granted $50,000 from the Warne Family Fund for 2019 to help support restoration efforts and to provide funds for field supplies, tools, and boots. The grant has also allowed the ASL events to expand to the first Saturday of every month.

An important endeavor under the USFWS grant and recently awarded Warne funding is to create maps of where ASL and ESL occur around Upper Newport Bay and to track the progress in areas that have been treated by hand pulling and solarization tarping. These maps will provide invaluable information regarding treatment success and which locations need prioritization in the future. To help with this considerable task, NBC is collaborating with UC Irvine, Chapman University, Project Grow, Tidal Influence, and the California Department of Fish and Wildlife to survey and develop mapping methods. In particular, Marcus Goncalves, a UCI master’s student in the Conservation and Restoration Science program and Project Grow Habitat Restoration Project Manager, has taken a leadership role in helping NBC generate standardized protocols and guidelines for mapping ASL. By working closely with NBC volunteers and local stakeholders, development of these tools will greatly strengthen NBC’s restoration and targeted invasive control efforts in Upper Newport Bay.








Text Box: A site along the Delhi Channel where ASL has created a dense mat, preventing native plants from growing. In the background is black tarping plastic laid out to treat areas such as this with extremely high density of ASL.







Text Box: A dense patch of ASL in full flower. Pulling ASL before flowering is critical so that it does not add seeds to the seedbank.









Photos by Howard Cork.