New Orleans uses 9,000 Christmas trees to restore coastal marsh

Every year, after the Christmas holiday, thousands of used trees are salvaged from landfills in New Orleans and repurposed to help combat coastal land loss. The initiative, which has been ongoing for nearly three decades, involves collecting the trees, bundling them, and dropping them in coastal marshes via helicopters to bolster the marshes' ability to withstand erosion and flooding.

This program is part of a larger effort to safeguard Louisiana's diminishing coastline, which has shrunk by nearly 2,000 square miles since the 1930s. Factors contributing to this decline include natural erosion, severe storms, rising sea levels, and subsidence - the sinking of land over time.

A major reason for the land loss is the reduced sediment flow from the Mississippi River, which has diminished due to factors like flood control measures and changes in river sediment chemistry. This sediment is crucial as it aids in rebuilding marshes by depositing soil, sand, and mud.

In a notable example, Bayou Sauvage Urban National Wildlife Refuge, situated near New Orleans, has benefited significantly from the Christmas tree restoration project. Nearly 9,000 trees were collected, bundled, and dropped into the marshes last March. These bundles, each containing around 50 to 60 trees, are strategically placed in shallow wetlands where they act as barriers. The trees slow down water flow, allowing sediment to settle instead of being carried away by currents.

Over time, the accumulated sediment raises the ground, creating a more stable environment for marsh grasses to grow. These grasses, in turn, help anchor the soil together with their root systems, reinforcing the marsh structure and providing habitats for various wildlife. Despite being temporary, the trees serve as essential support while sediment and plant roots gradually fortify the marshes, making them more resilient to erosion and storm surges.

The effectiveness of this method has been supported by scientific studies. A field study published in 1997 demonstrated that Christmas tree barriers can reduce wave energy reaching marsh beds by approximately half and facilitate sediment accumulation, sometimes at rates of up to 1.3 inches per year. However, the success of this method is contingent on proper placement, as deeper waters may impede the accumulation of sediment needed for marsh plant growth.

While the Christmas tree restoration program has contributed to the creation of roughly 115 acres of marshland, estimates vary. City officials have compared the restored area to approximately 200 football fields, though updates suggest it may be closer to 330 football fields. The project is expected to continue, with additional deliveries made during the 2025-26 holiday season, further aiding in Louisiana's ongoing coastal restoration efforts.