NEW ORLEANS (AP) — It’s a Christmas holiday tradition — a few months after Christmas — that benefits the Louisiana environment.

New Orleans officials joined Louisiana Army National Guard members and the U.S. Fish and Wildlife Service on Wednesday to place bundles of used Christmas trees in the waters of a wildlife refuge.

The trees are used to build marsh habitats.

“Not long ago, this marsh had turned into open water,” Pon Dixson, of the Fish and Wildlife Service, said aboard an airboat in the Bayou Sauvage Urban Wildlife Refuge. “We had a lot of subsidence … But since we’ve been doing the Christmas tree project in this portion of the marsh, you see the results. You see a whole lot more emergent marsh, a lot more cattails, a lot less open water.”

National Guard helicopters airlifted the trees to the Bayou Sauvage Urban National Wildlife Refuge, dropping them into shallow waters where Fish and Wildlife personnel removed the lines used to hoist the bundles and moved the trees into place.

New Orleans is among several Louisiana communities that collect the trees shortly after Christmas every year. The trees are bundled and placed in coastal areas, where they can stop wave action and trap sediment.

“We will have sediment that will build within those trees and we’ll start to build the habitat.”

Shelley Stiaes, a refuge manager for the Fish and Wildlife Service

And there is the added environmental bonus of the city having an alternative to putting the trees into landfills.

“The City’s Department of Sanitation contractors collected approximately 4,000 trees this year,” Mayor LaToya Cantrell’s office said in a news release. “Over the 25 years of this program, recycled Christmas trees have restored an area of marsh equal to approximately 200 football fields. The trees also create an important habitat for birds, fish, crabs, crawfish, and shrimp.”