Communities Restoring Urban Swamp Habitat

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The Project Location

The Communities Restoring Urban Swamp Habitat (CRUSH) project aims to restore the coastal forests within the Maurepas Land Bridge (MLB) in Akers, Louisiana,  and the Central Wetlands Unit (CWU) in Violet. Historically, the MLB and the CWU were covered with freshwater swamp forests dominated by bald cypress trees. These forests not only provided habitat for a variety of swamp species but were a critical line of defense in reducing storm surge for the communities around Lake Maurepas, East Baton Rouge and New Orleans.

Human-caused changes to the historical floodplain of the lower Mississippi River Delta have affected the health and stability of these areas, contributing to the loss of our coastal forests. In the late 1800s and early 1900s, the entire MLB and portions of the CWU were clear cut when regional cypress logging peaked, removing many of the mature trees needed to regrow the forest. Extensive leveeing, largely built for flood protection from 1927 onward, starved the swamps of nutrient-rich freshwater and sediment from the Mississippi River, essential for healthy growth and offsetting subsidence. In the 1930s, nutria, large rodents native to South America, were introduced for the fur trade, but this invasive species bred and spread. These voracious feeders consume vegetation at a considerable rate, essentially “mowing” new plant growth and killing young trees. In 1965, the Mississippi River-Gulf Outlet (aka MR-GO) was completed, provided a direct water route from the Gulf of Mexico to New Orleans. Unfortunately, the canal also allowed saltwater to encroach into freshwater marshes and swamps, increasing the salinity of the Pontchartrain basin and killing large areas of previously healthy wetlands. Smaller channels and canals, dug for oil and gas activities or navigation, further disrupted the movement of water over the landscape. This has left our coastal forests vulnerable , particularly in the face of severe droughts like in 1999-2000, which caused a spike in salinity and the resulting death of many trees.

Human impacts have so greatly disturbed the habitats around the MLB and CWU that natural recruitment, or the growth of seeds into saplings and then adult trees, is insufficient to restore these areas naturally. Cypress seedlings need a period of draw down, or low water, to germinate, but the swamps are now permanently flooded or have converted to marsh. The CRUSH project is designed to give these coastal forests a boost by planting young trees to restore the missing generations.

CRCL's Activities

In 2009, in response to continued and catastrophic impacts of storm surge and saltwater intrusion, the MR-GO was closed. With this closure, the basin has been slowly freshening, making the area suitable for the next generation of coastal forest to grow. To support the broad restoration efforts in the area, CRCL began the CRUSH project in 2018 to help restore these important wetlands by planting 7,500 trees through 2021. Over time, the saplings we plant will grow dense root systems, helping to hold and collect sediment, anchoring the swamp, increasing land growth and combatting subsidence. As the trees age and grow, they will help to reinforce a critical barrier that protects communities in East Baton Rouge, Lake Maurepas, St. Bernard Parish and New Orleans .

 

So far, CRCL has hosted more than 350 volunteers over 18 days of planting events. Together, we’ve planted nearly 6,000 trees to restore almost 40 acres of coastal forest. You can get more details and sign up to help restore our coastal forests HERE!

What We've Learned So Far

The disturbed habitats of the CWU and MLB create many challenges for our new saplings. Because the MLB is hydrologically disconnected from the Mississippi River, the area has become isolated and nutrient starved, which can reduce the availability of vital nutrients for the young trees. We plant our trees with a ring-shaped nutria excluder device, or NED, to reduce damage done by the voracious and prolific herbivores. Deer pea vine also poses problems for our newly planted trees. This native vine grows quickly and sprawls upward in its quest for sunlight, unfortunately smothering and sometimes even dragging over the relatively small saplings. Our plantings also have to face the threats of living along the coast – wind and surge from major weather events can smother or topple young trees that have yet to establish strong root systems, and break off their growing crowns in high winds. Young trees are also less tolerant of extended flooding that can come with storms, reducing their growth and risking their survival.

 

Our Restoration team monitors the survival and growth of the CRUSH project trees to help us understand our impact and learn how we can continue to do better into the future. So far, we’ve seen that our trees survive well in their first year, with a survival rate of more than 85% for saplings planted by our volunteers. Overall, the cypress saplings seem to handle the difficult conditions of these disturbed habitats slightly better than the other species with which we work. Survival isn’t the only important factor for these new trees; we also monitor their growth from year to year. While growth rates are slower for our CRUSH plantings than for some other sites in southeast Louisiana, we are pleased to see gradual growth in both height and diameter of our young saplings. We’ll continue to check on our trees as they grow, but we’re happy to see them adapting well to their new homes. We’re also excited to see plans move forward that will help to support healthy, thriving coastal forests in these areas. The state Coastal Protection and Restoration Authority has plans for both Maurepas and Central Wetlands Diversion projects, which will help to reconnect these systems to the nutrient-rich river and defend against drought. Planned ecosystem restoration projects in the MR-GO region will help to rebuild and sustain a healthy wetland barrier, providing protection against saltwater intrusion and storm impacts. Our efforts, combined with that of other groups across Louisiana’s coastal landscape, will help these young trees support a whole new generation of coastal forest for us to benefit from and enjoy.

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