Save The Bay's on-the-ground wetland restoration projects, completed with volunteer labor, are creating important buffer areas adjacent to tidal marshes. Our goal is to re-establish native plants in the "transition zone" – narrow areas of vegetation located between Bay water and land.
Unique Transition Zone Habitat
The unique transition zone habitat has been negatively impacted by the conversion of wetlands into agricultural lands and commercial salt ponds, as well as shoreline development. Further, hundreds of miles of levees have been constructed on top of the transition zone. Unlike tidal flats, which can be restored fairly quickly by the re-establishment of tidal influence, transition zone vegetation doesn't thrive without human assistance.
The Bay needs more of this buffer area surrounding our tidal marsh because it:
- Creates safe habitat for Bay animals to retreat when the water level rises during storm events or high tides
- Serves as a natural buffer against storm surges and future sea level rise, helping to protect neighborhoods from flooding
- Stabilizes soil to prevent erosion of important levees
- Filters runoff pollution to improve water quality
- Supports a high biodiversity of plants and animals that can live only in this zone
Photo: Judy Irving
Save The Bay Scientists Pioneers in Transition Zone Restoration
Save The Bay and scientists from the San Francisco Estuary Institute are working together to ensure more successful restoration of transition zone habitat around the Bay. We have developed a method to monitor and gather data from restoration sites. We are sharing our key findings about effective and economical planting and weed removal with land owners, restoration managers and other organizations committed to restoring San Francisco Bay.
It Takes A Village
Our volunteers are an invaluable part of achieving our restoration goals, supporting maintenance, planting and nursery work. Volunteers participate in all aspects of our restoration activities like:
- Collecting native plant seeds onsite
- Tending plants at our on-site nurseries
- Sowing plants along the shoreline
- Removing invasive weeds and trash that degrade the Bay
- Long-term maintenance of restoration sites
More than 5,000 volunteers work with Save The Bay annually to restore our Bay shorelines. When you volunteer, you gain valuable knowledge about wetlands and the Bay while improving habitat for fish, birds, and other wildlife and enhancing our region's quality of life. It's fun, too! Get your hands dirty and be a part of making the Bay healthier for all of us.
What is unique about the tidal marsh transition zone?
By Darcie Goodman Collins, Ph.D. former Save The Bay Habitat Restoration Director
In nature, narrow strips of vegetation (less than 10 meters) between two types of habitat is a transitional zone. The characteristics of these zones are defined by interactions between the two systems they join. In our own San Francisco Bay, the border between the marsh and upland is marked by this narrow transition zone. In this zone there are abrupt changes in plants and other species. This zone concentrates organic material, nutrients and organisms.
While habitat below the mean high tide can re-establish itself voluntarily under the right conditions, transition zones do not rapidly re-establish native vegetation following breaches that restore tidal action. Because of the resources and long-term commitment required, less attention has been paid to the restoration of upland transition zones.
In San Francisco Bay, these transition zones are often appear on levees built with non-native soil in which native plant growth is minimal. These levees are often characterized by steep grading, highly saline soils from former salt production, and visible shifts in vegetation types. Invasive plants such as Mesembryanthemum crystallinum Crystalline (Iceplant) and Foeniculum vulgare (Fennel) have taken over many of these transition zones and outcompete native species.
Yes, undisturbed, functioning transition zones serve as high tide flood refuge for wildlife by providing cover from predators. Therefore, unmanaged, these transition areas usually inhibit the full potential of returning full ecosystem functions to the tidal marsh. Healthy transition zones are also necessary for restored marsh to keep pace with sea level rise and to offer natural buffers to protect communities from flooding and storm surges.