Shelter From the Storm
Coastal wetlands provide essential protection
by Carol Whitlock
A recent article published in the journal AMBIO suggested that coastal wetlands provide invaluable protection against hurricane damage, both in terms of dollars saved and in improvements to quality of life. One example showed that the estimated 1.2 million acres of Louisiana wetlands that were lost before Hurricane Katrina represented an annual loss in storm protection of $28.3 billion, and that coastal wetlands impacted by Katrina caused another $1.1 billion in lost protection. Although there is little agreement about specific dollar amounts, there is growing consensus that the best way to reduce the effects of hurricanes in the Gulf Coast area is to preserve and restore coastal wetlands.
The most expansive coastal wetlands along the Gulf Coast were formed by the great rivers that drain the midsection of the United States into the Gulf of Mexico. With each flooding of the Mississippi River and its tributaries, sediment-laden water from the North seeped onto the floodplain and filtered through the river delta, rejuvenating the bottomland hardwood forests and coastal swamps and marshes of this great river system.
With European settlement came concern that the flooding which nourished the wetlands would endanger lives, destroy homes, and disrupt agricultural and commercial activity. Hence the levees.
At first, levees were only used to protect major cities, with areas in between still subject to the flooding that’s the lifeblood of these wetlands. But gradually the Mississippi has ceased to resemble a leaky garden hose slowly releasing nutrients into surrounding wetlands. Instead, it’s turned into a canal that rushes sediments enriched with nutrients from agricultural runoff directly into the Gulf of Mexico. Diverted past bottomland forests and coastal swamps and marshes they once nourished, the nutrient-rich sediments now feed vast plumes of algae that, when they die and decompose, deplete oxygen in the water, forming “dead zones” where almost nothing can live. Meanwhile, coastal swamps and marshes, deprived of their lifeblood, have become vulnerable to more degradation and loss from other natural and anthropogenic factors.
In 2004, recognizing the problem of diminishing wetlands, Louisiana Governor Kathleen Blanco appointed Louisiana State University professor Jim Chambers to assemble natural resource experts to develop a set of recommendations for the utilization, conservation, and protection of the State’s coastal forest wetlands. Emile Gardiner, research forester with the SRS Center for Bottomlands Hardwood Research in Stoneville, MS, was among 12 scientists commissioned by Governor Blanco to form the Coastal Wetland Forest Conservation and Use Science Working Group.
The working group found that the harvesting of baldcypress in coastal swamps could exacerbate the loss of forested wetlands already severely degraded by other factors such as canal dredging for oil and gas production, levee construction for urban and agricultural development, invasion by exotic plants and animals, rising sea levels, and land subsidence. These alterations threaten forested wetlands by adding too much water at the wrong times, producing greater depths and durations of flooding and shortening the dry spells needed for seed germination and establishment of seedlings that become the next generation of baldcypress and water tupelo. The concern is that the current hydrologic trend is transforming cypress-tupelo forests into floating marshes and open stretches of water where no forests can grow.
Gardiner and his colleagues completed their work in the spring of 2005. In their final report, they established three wetland forest regeneration condition classes: class I, sites with potential for natural regeneration; class II, sites that can only be reforested by artificial regeneration; and class III, sites with no potential for regeneration. For class I sites, the working group recommended that the State place a priority on maintaining current hydrologic conditions. For both class I and II sites, the working group recommended that the State require management plans for all harvesting operations. And for class III sites on State managed lands, the working group recommended a halt to all harvesting.
It’s an understatement to say that the efforts of Gardiner and his colleagues were overtaken by events on the ground. The double-fisted punch of two major hurricanes a few months after the release of their report both underscored the value of wetlands and compromised the State’s ability to carry on the important wetlands work in the face of urgent infrastructure needs.
Despite enormous recovery challenges in the years following Hurricanes Katrina and Rita, Louisiana has continued to place emphasis on finding solutions to the loss of forested wetlands, including the establishment of Interim Best Management Practices and the identification of research priorities for coastal forest regeneration. Clearly, there will be steep challenges in the effort to safeguard and restore Gulf Coast forested wetlands while maintaining the ability to use forest products, protect communities, and extract mineral energy.
For more information:
Emile Gardiner at 662–686–3184 or