About 15 miles east of downtown New Orleans, the nation’s second-largest urban wildlife refuge rests on an isthmus between Lake Pontchartrain and Lake Borgne—a region constantly pummeled by storms off the Gulf of Mexico. Bayou Sauvage National Wildlife Refuge has played a major role in the protection of one of the largest metropolitan areas at risk of gulf storms and flooding.
Fifteen years post-Hurricane Katrina, the refuge has been conducting restoration and breakwater projects like the annual Christmas tree drop to rebuild the refuge and protect against shoreline erosion.
“We’re floating,” said Shelley Stiaes, refuge manager for the U.S. Fish and Wildlife Service. “You don’t feel it, but we are.” She described how Louisiana’s loose sediment landscape has been sinking into the Gulf Coast, making the area increasingly vulnerable to coastal erosion. “That’s another problem: subsidence in New Orleans. When you get these storms or heavy rains, everything will flood.”
Natural protection features like barrier islands and beach ridges obscure the interior wetlands—and the city—from the waves, wind and storm surges that beat down upon the coastline. Levees were built in addition to keep the water out but consequently created what Stiaes calls a “bowl,” with New Orleans resting in the basin about six-feet-below sea level.
Bayou Sauvage has less than 5% of natural levees with enough elevation or drainage to support the ecosystem. With the help of The U.S. Army Corps of Engineers, the refuge built a multi-million-dollar levee system around the conservatory. Smaller levees were built inside the refuge, which created miniature bowls, so pumping systems were installed to pipe the water that gets trapped back out.
After Hurricane Katrina, 80% of the refuge’s forest was toppled by wind or oversaturated by saltwater that flooded in with the storm surge.
“This used to be a closed canopy,” said Stiaes gesturing to the absent forest awning over the Ridge Trail boardwalk. In 2008, the refuge began reforestation initiatives to restore vegetative growth by planting trees that support native and migrating wildlife. The refuge began partnering with scientists to monitor vegetation growth and worked with at-risk youth, who got experience in the environment repairing boardwalks, planting native flora and removing invasive growth.
“Some of the largest cities, especially New Orleans, collect Christmas trees,” said Brian Pember, assistant refuge manager at the Mandalay National Wildlife Refuge outside of Houma, Louisiana. “Bayou Sauvage got hammered during Katrina, so they’re still trying to restore it. That’s a really effective way to help protect the shoreline.”
Since much of the refuge’s marshland was broken apart by Katrina, Bayou Sauvage asked New Orleans’s residents to donate their bare post-season Christmas trees to repair flood barriers within the conservatory. The annual project began before Katrina, though it was all done manually by the refuge workers. After Katrina, it developed into a large-scale collaboration between the City of New Orleans and its citizens, the Department of Sanitation and the Louisiana Army National Guard among others.
Upcycled Christmas trees are bundled into groups of 50, strapped into a harness and airlifted three-at-a-time into the marsh via helicopters. The exercise is useful training for the Louisiana Army National Guard with the objective of laying a straight line of trees across the marsh from one poll to another. Then on an airboat, refuge workers and volunteers untie and retrieve the harnesses from the crib.
The crib of recycled Christmas trees reconnects islands and marshland within the refuge and acts as a wave-break by obstructing the shoreline from wave erosion. The dulled water motion allows for new vegetative growth and traps silt, which helps strengthen the shoreline.
In 2019, more than 9,000 trees were estimated to have been lowered into the refuge, creating a wave-break visible from Google Earth.
“By the time the Christmas trees have rotted, sediment has dropped out some of the emerging vegetation, like bulrushes, which grow out and protect the shoreline,” said Pember.
Similar cribs have been built at the Mandalay National Wildlife Refuge, which consists of more than 4,000 acres of freshwater marsh and is intersected by the Gulf Intracoastal Waterway. Being a wetland conservatory, the refuge is made up of swamp and marshland that can only be accessed by boat.
Busted up concrete piled along the shoreline helps prevent the marshland from eroding into the waterway. Repurposed Christmas trees like those at Bayou Sauvage were collected behind a wooden crib, providing a healthy barrier for the flotant marsh and loose mats of vegetation that shift in the wind and water. Often, regrowth can be seen inside the Christmas tree cribs.
“On the calm side, we get more vegetation. Birds pass by and drop seeds—I’ve seen stuff growing out of the tree.” said Stiaes. “It’s a very beneficial project. It involves the citizens of New Orleans—they get to give back.”