Science for a Blue Planet

Featuring cutting-edge work, discoveries, and challenges of our scientists, our partners, and the larger conservation science community.

Healthy Transitions

Point Blue and a group of conservation organizations are joining forces in an effort to set the stage for restoring and improving the health of wildlife and human communities around San Francisco Bay for decades to come.   In a new study funded by the National Wildlife Federation’s San Francisco Bay Conservation Fund, Point Blue will be working with Save the Bay, San Francisco Bay Bird Observatory, San Pablo Bay National Wildlife Refuge, Don Edwards San Francisco Bay National Wildlife Refuge, and the San Francisco Bay Joint Venture to learn what is needed to maximize the benefits from transition zone restoration, identify metrics that best demonstrate restoration benefits, and how best to measure them.

Like the area where two countries meet, transition zones in nature are relatively small, but packed with activity and significance. They are areas where two habitats meet and integrate. Over time, under different conditions, these zones shift and play an important role in defining habitats and providing important functions for wildlife.  They are even more important under rapid changes from global warming.

The tranzition zone plant community can tolerate a gradient of water inundation and salinity, from pickleweed to elderberry.
The transition zone plant community can tolerate a gradient of water inundation and salinity, from pickleweed to elderberry and provides refuge from rising tides.

With sea levels rising at a faster pace than we’ve ever known, coastal wildlife need more areas to take refuge from extreme tides and floods and habitats need more space to move in order to adapt.  Around the San Francisco Bay a transition zone of particular importance is between salty, low elevation tidal marsh and drier, higher elevation upland habitat: the tidal marsh/upland transition zone.  This buffer area is where Ridgway’s rails and salt marsh harvest mice can take shelter during extreme high tides, and where special sub-species of Song Sparrows and Common Yellowthroats can forage and hide from predators. It’s an area that is highly dynamic and in short supply.

Ridgway's Rail
Ridgway’s Rail

“As the sea rises, these transition zones will become the marshes of tomorrow but only if we protect and restore them now,” says Julian Wood, Point Blue’s San Francisco Bay Program Leader.

Though a good deal of tidal marsh restoration has occurred over the past couple of decades, restoration efforts of this unique transition zone have occurred only more recently.  For example, Point Blue’s community-based restoration program, STRAW, has involved thousands of students and teachers in restoring over 6 acres of tidal marsh/upland transition zone around the San Francisco Bay.  These restorations included ample education for participants about the value and function of this zone.  This is a great start, but more is required.  Conservation practitioners need to know what makes a transition zone healthy, useful, and robust in the face of climate change.

Students and teachers restore a transition zone at Sear's Point with Point Blue's STRAW Program.  Photo: Leia Giambastiani/Point Blue
Students and teachers restore a transition zone at Sear’s Point with Point Blue’s STRAW Program. Photo: Leia Giambastiani/Point Blue

Luckily Northern California voters helped pass measure AA which will designate parcel tax funds for doing more and improving habitat restoration around the SF Bay. A large portion of this funding will be used to restore both tidal marsh/upland transition zone habitat and potentially, hybrid nature-based solutions that combine tidal marsh restoration with engineered flood protection. In both cases, we need to understand the best approaches for creating tidal marsh/upland transition zone habitat.

“Restoration of tidal marsh habitat has been a high priority for Point Blue and its partners, due to the extensive loss and degradation of tidal wetlands in the 19th and 20th centuries, to the detriment of wildlife and human communities. However, healthy tidal marsh requires a healthy, effective transition zone, and this, too, must be restored,” says Point Blue Quantitative Ecologist, Dr. Nadav Nur who is leading this latest transition zone wildlife benefit assessment.  “Very little natural transition zone is currently in place, and determining how to most effectively recreate the transition zone is a critical next step.”