Study Finds “Portfolio Approach” Can Help Protect Restorations From Extreme Climate Events

by Kristen Goodhue, Smithsonian Environmental Research Center
February 15, 2022

Knowing how to protect their communities from climate change has become a staple for local governments. Restoration projects—be they forests, wetlands or coral reefs—are no exception. However, many projects only account for gradual impacts, like sea level rise. They are often woefully unprepared for extreme events, like hurricanes or droughts.

A new study published Feb. 15 offers evidence for a promising solution: Treat restoration projects like stock investments. Creating a “portfolio effect” by diversifying certain aspects, like species or location, could give them a better shot at withstanding unpredictable extremes.

“You need to not put all your eggs in one basket,” said Chela Zabin, lead author and marine biologist at the San Francisco branch of the Smithsonian Environmental Research Center (SERC). “Because we just don’t know, really, how extreme an event’s going to be, what form it’s going to take, where it’s going to hit, how severe the impact might be.”

Zabin and her coauthors witnessed this firsthand during the winter and spring of 2017, when extreme rainfall devastated one of their oyster restorations with the San Francisco Bay Living Shorelines Project. The downpours topped anything seen since California records began in 1895. The water’s saltiness plummeted to five parts per thousand—a level Olympia oysters can withstand for days but not months. Not a single oyster at the site survived.

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