Louisiana's Cheniers and Natural Levees
High Ground Provides Vital Habitat, Defends Against Storms

At ground level, the elevation scarcely looks intimidating. Even in a Louisiana summer a person may stroll to its summit without breaking into a sweat. Only the most detailed topographic map depicts it with a contour line. But in the flat coastal landscape, a 10-foot ridge of sandy soil is a crucial geological feature, providing dry habitat and serving as a bulwark against invasive waves and storm waters.

In Louisiana, ridges form a critical line of defense against storms. Even cheniers and natural levees rising no more than three or four feet contribute consequential protection to the region’s communities and coastal ecosystems. “Cheniers act as a breakwater to hurricanes and slow down the storm surge,” says Tina Horn, Cameron Parish administrator. “They restrain waters pushing in from the Gulf of Mexico. Without them, we would see the reach of floods extend much farther inland — north of Johnson Bayou to the town of Sulphur, and north of Cameron to Lake Charles.”

Protective partnerships between landscape features

Providing elevation above sea level for residential and commercial development, cheniers are remnant beaches stranded among stretches of marsh. “Island” in the name of some cheniers, like Pecan Island, indicates the isolation of these ridges in an expanse of wetlands.

Marshes and ridges provide complementary protection. During normal weather, even a three-foot-high chenier blocks salt water from reaching marshes behind it. During storms, the mile or two of marsh surrounding most cheniers helps to reduce tidal surge and calm wave energy. “If a marsh in front of a chenier reduces a 15-foot storm surge by five feet,” says Darryl Clark, senior biologist with the U.S. Fish and Wildlife Service, “that’s obviously significant to people and animals taking refuge on a 10-foot-high chenier.”

The vegetation supported by ridge elevations adds to their protective capacity. “It’s not just the ridges but also the trees that grow on ridges that are important in quelling storms,” says Richard Martin, director of conservation programs for The Nature Conservancy’s Louisiana field office. “In 2005, homes built in wooded areas withstood Hurricane Rita better than structures that were exposed.” And native species like live oak and hackberry weather storms better than shorter-lived, invasive species such as the Chinese tallow tree.

Erosion and wetland degradation pose the greatest dangers to Louisiana’s centuries-old cheniers and natural levees. Recognizing the importance of these landscape features in the coastal environment, current plans for safeguarding them take a dual approach:

• restore shorelines along the gulf and inland water bodies to reduce the erosive threat that waves pose
• improve the health and protective capacity of marshes flanking ridges by controlling saltwater intrusion and by using diversions and dredged materials to nourish and rebuild them

Private efforts preserve high-ground habitat

While recent government activities focus on building levees for flood protection, other ongoing efforts, both public and private, concentrate on conserving forested ridges.

Conservation tools range from programs supporting conversion of farmlands back into native wetlands to conservation servitudes, or easements, to outright purchases of property for natural preserves. “Hundreds of nonprofit and public agencies are working on habitat and species’ protection,” says Martin. “But we’ll achieve our long-term goals only if our country increases its level of awareness about endangered species, habitat loss and other conservation issues.”

The Nature Conservancy’s project on Grand Isle brought attention to the hemispheric phenomenon of migratory songbirds making landfall on the Louisiana coast. The vegetation growing on barrier islands, ridges and cheniers provides food and shelter that sustain the life of millions of birds. “The Nature Conservancy bought land,” says Martin. “We gave away trees. We encouraged residents of Grand Isle to plant native trees — even just one. Local businesses made donations and the town council lent their support to our project. The area’s major industrial landowner allowed tree plantings on its property. We worked with school kids to collect seed and grow native plants for their yards. The intent was to expand the amount of habitat available to migratory birds, but the project instigated an awareness of conservation that reached far beyond the tree canopy of Grand Isle.”