“These natural systems are the front line — the places that are between the open ocean and New Yorkers,” Mr. Ulfelder said. “The more we can do to invest in these, the better they’re going to be in helping to protect us.”

The conservancy, along with the Jamaica Bay-Rockaway Parks Conservancy, National Park Service and hundreds of volunteers, is wrapping up a three-year project to cover 14 acres of the Jamaica Bay Wildlife Refuge with trees and shrubs. When Sandy flooded the area, the plants there could not tolerate the salty, wet conditions, said Emily Nobel Maxwell, the New York City program director at the conservancy. But the plants that they are placing there — a vibrant “maritime forest” of oaks, pines, juniper, holly, blueberry and elderberry — can better tolerate saltwater inundation.

“The expectation is that they will be under water more often in the future, as the surges happen,” Mr. Ulfelder said. “When the water washes around them, they will be able to survive some of those events, whereas the previous species could not. They’re designed to be compatible with a sea-level-rising world.”

If it’s successful, Mr. Ulfelder and Ms. Maxwell said, the project can serve as an example for other parts of the city susceptible to water damage.

The group’s goal is to plant 28,000 trees there. If you’re interested in volunteering to help, you can sign up to participate this Saturday from 10 a.m. to 3 p.m., or next Saturday and Sunday at the same time.