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Swamps Can Protect Against Climate Change, If We Only Let Them


One authority on water, William Mitsch, has suggested that if ten per cent of the old Black Swamp soils were allowed to become wetlands again they would cleanse the runoff, yet Ohioans remain powerfully anti-wetland. Even private efforts to restore small wetland areas are met with neighbors’ complaints about noisy frogs and fears of flooding. Still, despite all odds, there exists the Black Swamp Conservancy, a land trust that oversees twenty-one thousand acres of wetlands. Hundreds of active Black Swamp Conservancy members are doing their best to restore and protect remnants of this great swamp. Can they persevere?

My mother’s favorite book when she was a teen-ager, in the nineteen-twenties, was one that she loved for its swamp setting, Gene Stratton Porter’s “A Girl of the Limberlost.” The Limberlost Swamp is in northeast Indiana, forty miles west of the Great Black Swamp. Porter’s home was near the Limberlost, which, though small at thirteen thousand acres, was still a diverse and complex system of streams and ponds eventually draining into the Wabash River. The Limberlost was made up of timber, reeds, sphagnum moss, orchids, sundew, pitcher plants, and grasses that nurtured great crowds of waterbirds and migratory birds, snakes, frogs and other amphibians, deer, muskrat and beaver, mink, and an encyclopedia of insects, including rare moths and butterflies.

There are at least two and probably more stories of how the name Limberlost originated. In one, a man named James Miller, so physically agile he was called Limber Jim, was hunting in the swamp. He became hopelessly lost, walking in deadly circles before he began to blaze trees in a straight line. His friends of him found him and referred to the swamp ever after as the place where Limber was lost. Another story refers to Limber Jim Corbus (what is it with these flexible Indiana men?), who also set out for a day’s hunt in the swamp and became lost, but blazed no trees and was never found.

Despite being considered a “nature” novel, “Girl of the Limberlost” is the usual American story of taking from nature for personal gain. The book champions its heroine, Elnora, who collects the chrysalides of moths, then raises, kills, and mounts them. After her miserable first day in high school, where she is scorned as an out-of-fashion backwoods hick, she sees a placard in the local bank window offering cash for moths, cocoons, and pupa cases. Elnora needs money to buy the kind of nice clothes and cosmetics that will let her join modish high-school cliques and pay for her books de ella. She describes her de ella moths de ella to the placard’s writer, who tells her, “Young woman, that’s the rarest moth in America. If you have a hundred of them they are worth a hundred dollars according to my list.” Elnora is on her way to wealth, a career, a rich husband, and all the rest of it, thanks to the corpses of the Yellow Emperor moth.

Against Porter’s protests, the Limberlost was ruinously drained for farmland by steam-powered dredges between 1888 and 1910. But in the nineteen-nineties Indiana readers who treasured Porter’s book bought some of the original swamp acreage and, with help from several conservation groups, started restoring the swamp by removing drainage tiles. As the water deepened, they planted native sedges, grasses, trees, and water plants. Today, a small piece of the Limberlost exists again, serving as a tourist attraction and a home to muskrats, ducks, herons, turtles, fish, and insects. The Yellow Emperor moths are still around.

It is an important decision to restore even a small piece of wetland that has been severely mauled—once land is apportioned to owners, there can be no easy path to restoration of a natural habitat. Bogs and swamps take thousands of years to build up and develop; humans and their machinery can wipe out those centuries in a few months. But once a few interested people put on their boots and go into the damaged wetland, and once their curiosity is aroused about how the water moves, and what plants, amphibians, and birds formerly thrived in their local remnant swamp, they are hard to stop . There is unequaled joy in restoration.

Mangroves are marine trees. They grow in brackish and saline water along Southern and tropical shores—their splayed-out roots resemble the “cages” that supported Victorian hoop skirts—and they form peat. Their specialized home ground, such as Florida’s Everglades, is smelly and muddy. There are roughly sixty species of mangrove, mostly found in Asia, and the strongest forests are those of mixed species. Mangrove swamps have been called the earth’s most important ecosystem, because they form a bristling wall that stabilizes the land’s edge and protects shorelines from hurricanes and erosion, and because they are breeding grounds and protective nurseries for thousands of species, including barracuda, tarpon, snook , crabs, shrimp, and shellfish. They take the full brunt of most storms and hurricanes, and generally survive—but not always. Hurricane Irma, in 2017, hit the mangroves of Big Pine Key, in Florida. While shrubs came back after a time, the mangroves did not. Some saw the cause of mangrove death as trapped standing salt water, but others thought that the storm surge had plastered a very fine coating of sediment on the vital aerial roots, which dried into a choking hard sealant.

Mangrove leaves fall into the water and, as they decay, become the basis for a complex food web benefitting algae, invertebrates, and the creatures who feed on them, such as jellyfish, anemones, various worms and sponges, and birds. The peat that mangroves form is especially soft and deep, ideal for clams and snails, crabs and shrimp. The mangrove’s roots filter out harmful nitrate and phosphate pollutants. The tangled branches above the water make a safe habitat for literally thousands of species of insects that attract birds. They offer resting places for migrating birds and nesting places for others, including kingfishers, herons, and egrets. Monitor lizards, macaque monkeys, and fishing cats on the hunt prowl the branches. Below the water, the knots of interlaced roots protect tiny fish from the ravenous jaws of larger fish, and even manatees and dolphins take refuge in these swamps. Mangroves interact with coral by trapping muddy sediment that would smother the reef, while the offshore reef protects the mangroves and seagrass beds from pummeling waves. Structurally, mangroves form an enormous hedge that extends down into the water and high above it. They are a major part of the “blue carbon” group that absorbs COtwowhich also includes the salt marshes, seagrasses, and beds of kelp and other seaweeds.

With all these virtues, it would seem that mangroves must be the most valued trees on earth. Unfortunately, that is not the case. Although climate researchers see mangrove swamps as crucially important frontline defenses against rising seawater and as superior absorbers of COtwo—they are five times more efficient than tropical forests—they are in big trouble, and mangrove removal is a constant threat.

In 2010, a count showed that about fifty-three thousand square miles of mangrove forest protected the earth’s coasts. But six years later thirteen hundred square miles of mangroves had been lost to palm-oil and rice farms and shrimp aquaculture. In some cases, mangrove forests have been removed to make room for shrimp ponds; in other cases, the shrimp ponds are set back from the mangroves, but the released effluents and pollution still damage and degrade the mangrove forest by changing the water’s salinity, altering the mangrove’s ability to take in nutrients. The consequence is slow death for the mangroves.

Many countries have tried to master the complexities of mangrove restoration, with mixed results. Choice of the right site and a mutually beneficial mix of species is critical. Some well-intentioned restorers planted greenhouse-raised single-species saplings in mudflats that mangroves had never grown in, or that were exposed to erosion and strong waves. Yet mudflats have a low oxygen supply because they are constantly wet, and mangroves need to breathe.

A different approach was that of the Florida biologist, ichthyologist, and wetlands ecologist Roy (Robin) Lewis III, who worked out the details of effective mangrove restoration. Repetitive observation can unravel the mysteries of events and processes. Lewis, who was born in 1944, was still a graduate student when he began working in mangrove swamps. “I spent a decade working in the mangroves before I started to have an understanding of what was going on,” he once remarked. I have dedicated years to puzzling out the rhythms of mangrove happiness. I have observed that, in the natural order, when a mangrove tree died, plentiful seeds from nearby healthy mangroves floated in and rooted themselves. The problem with many restoration attempts was location. Just any random part of a shoreline would not work. The flow of water had to be correct. Mangrove roots need to be sometimes wet and sometimes dry. Lewis worked out a wet-dry ratio of thirty to seventy. “They have a short period of wetness, and then they have a long extended period of dryness, and those alternate daily,” he told a reporter for the Smithsonian Institute. “That’s the secret: you’ve got to replicate that hydrology.”

His first trial of this theory came in 1986, with thirteen hundred acres of damaged and dead mangroves half smothered in dirt and weeds on a flat site near Fort Lauderdale. After several years of experiment and study, Lewis brought in earth-moving equipment to create a gentle slope of land that would allow the natural tidewaters to ebb and flow. Then I have waited. The tides brought mangrove seeds that took root, and five years later three local species of mangroves were growing. Fish moved into the sheltering roots, and the birds followed. No mangrove saplings were hand-planted; all the new trees grew from waterborne mangrove seeds. Lewis’s way of working with nature—observation and study, planning and patient waiting—has become the gold standard for restoration.

It is usual to think of the vast wetland losses as a tragedy, with hopeless conviction that the past cannot be retrieved. Tragic, indeed, and part of our climate-change anguish. But as we learn how valuable wetlands are in softening the shocks of the changing climate, and how eagerly the natural world responds to concerned care, perhaps we can shift the weight of wetland destruction from inevitable to “not on my watch.” Can we become Thoreauvian enough to see wetlands as desirable landscapes that protect the earth while refreshing our joy in existence? For conservationists the world over, finding this joy is central to having a life well lived.

It is of course possible to love a swamp. I remember another small and nameless Vermont larch swamp, which could be reached only by passage through a dark and gloomy ravine that I thought of as the Slough of Despond.

At the bottom of the ravine ran Jacobs Chopping Brook. The flurried, emotional water of the brook contrasted with the black glass disk of swamp water that seemed made to reflect passing clouds but under rain showed itself as dimpled pewter. It has been fifty years since I last saw it, but it is still with me. ♦

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