World / Science & Health

Bringing the world's buried wetlands back from the dead


Ghosts ponds lie all around the gently rolling farmlands of eastern England. Over the years, landowners filled them in or let them fade away, erasing entire ecosystems.

England is just part of the decline of wetlands worldwide, which has brought an array of environmental calamities, from rising floods to species hurdling toward extinction.

There are some who are trying to reclaim these lost bodies of water. In eastern England, farmers, university researchers and conservationists are digging into barley and wheat fields to turn back the clock. They seek out patches of muddy earth that hint at lost ponds lurking beneath.

Using chain saws, an excavator and plenty of sweat, the team takes just a few hours to resurrect one dying pond near Hindolveston, a thousand-year-old village not far from the North Sea. They fell trees and shrubs, then start digging until reaching their goal: an ancient pond bottom that once supported plants and insects, and the birds and animals that fed on them.

“As soon as they get water and light, they just spring to life,” said Nick Anema, a farmer in nearby Dereham who has restored seven ponds on his property. “You’ve got frogs and toads and newts, all the insects like mayflies, dragonflies, damselflies.”

But the battle for the wetlands is a struggle. While efforts are underway to stem losses and regain some of what has been lost, wetlands around the world continue to be filled in and plowed over.

Almost 90 percent of the world’s wetlands disappeared over the past three centuries, according to the Ramsar Convention, an organization formed around a 1971 treaty to protect wetlands. The loss rate has accelerated since the 1970s, with wetlands now disappearing three times faster than forests, the group says.

Every type of wetland has suffered — from ponds, swamps and coastal marshes to fens, bogs and other peat lands.

The consequences can be profound:

Roughly 5,000 wetland-dependent species are threatened with extinction, including mammals, birds and amphibians.

Fewer natural storage areas to hold back torrential rains means more severe floods in many parts of the world.

Draining wetlands, such as in Indonesia to make way for palm oil plantations, can release huge amounts of carbon dioxide, a major contributor to climate change.

Climate change also threatens to worsen the problem. Warmer temperatures and changing rainfall patterns can trigger drought, leading to more pumping of water reserves that otherwise would feed wetlands.

Wetlands in northern China, the central U.S., northern Africa, India and the Middle East already have been depleted by the pumping of aquifers for agriculture.

“We now know the value of wetlands, and we know with increasing precision how many wetlands we’re losing. The next step is for the governments to act,” said Royal Gardner, director of the Institute for Biodiversity Law and Policy at Stetson University in Florida.

Prairie ponds

A few hours of heavy rain in North Dakota is all it takes to transform the dry, cracked prairie earth into thousands of pocket wetlands.

Rain pools in shallow depressions known as prairie potholes — carved into the earth by glaciers 10,000 years ago — and flushes out insects from beneath the soil. Each pothole becomes a haven for a pair of ducks.

Spring and fall bring clouds of migrating snow geese that descend en masse, lingering for a few days on the larger ponds as they pass between breeding grounds in Canada and their winter refuges to the south.

But to farmers, these wetlands bog down tractors, rot newly planted seeds and can kill young crops. Some farmers steer around them, planting seeds in swirling patterns to avoid wet patches. Other wetlands are removed, often to make way for corn.

Despite their mind-boggling numbers — several million potholes are spread across five states and three Canadian provinces — these wetlands are steadily being drained or plowed under. Iowa has lost 99 percent of its wetlands and Minnesota has lost 95 percent, according to U.S. officials. The Dakotas and Montana have seen smaller declines.

Hundreds of millions of dollars have been spent trying to reverse or at least halt the losses.

That includes payments to North Dakota ranchers like Cody and Deanna Sands in Ellendale. Aided by the U.S. Fish and Wildlife Service, the Sands have plugged ditches on their pastures. That lets the water pool, helps grow grass for their cows and creates nesting areas for grassland and water birds.

Now they worry less about having enough rain and spend more time marketing their beef.

The region’s future, experts say, comes down to a numbers game — one that so far is tilting against the potholes as wetlands are sacrificed to feed demand for the corn-based fuel ethanol.

“We’re losing more habitat than we’re gaining,” U.S. Fish and Wildlife Service biologist Jon Beyer said. “The small, shallow wetlands attract the birds, and those are the ones at highest risk.”

Natural versus artificial

Only human-made wetlands buck the global trend toward decline. Rice paddies, reservoirs and agricultural stock ponds all increased in area since the 1970s, according to Ramsar.

Schott, a third-generation farmer in the small community of Kulm, North Dakota, recently installed networks of perforated pipes beneath some of his fields to drain off the standing water. The water will get pumped into a nearby pond, making each acre drained “as productive as we can get it.”

Under federal regulations, he must offset the losses, or lose his federally subsidized farm insurance and be ineligible for other government assistance. He is doing it somewhat reluctantly, installing a berm across a low area in one of his fields to create a small pond.

Schott, other farmers and their political allies in Congress want wetlands less than an acre (0.4 hectare) in size — such as the three he recently drained — to be exempted from the offset requirement.

The guiding principle is to have no net loss of U.S. wetlands. A similar tactic has been adopted in China, home to about 10 percent of the globe’s wetlands.

Yet in both nations, scientists are concerned that the approach papers over significant differences between natural wetlands and those created by humans.

While Schott’s pond will meet the law’s requirements, government biologists and wetlands advocates say such projects don’t fully restore what has been lost, because a larger pond with water year-round doesn’t fulfill the same ecological role as the smaller wetlands they are supposed to replace.

A group of researchers at the Chinese Academy of Sciences raised similar concerns in a September study, warning that statistics showing a slight increase in China’s total wetlands area between 2000 and 2015 obscured what really happened. A significant portion of the increase came from the construction of dams that turned areas with many small wetlands into large reservoirs, the researchers found. The combined area covered by natural marshes decreased by almost 3,000 square miles (7,600 square kilometers) during the same period.

“People brag about the fact that there’s been no net loss. But what they’ve done is destroy natural wetlands and created artificial ones,” said Stuart Pimm, a Duke University professor who worked with the Chinese researchers. “It makes it look like you’re doing no harm, when the reality is very different.”

English restoration

Since the start of the 20th century, 75 percent of the United Kingdom’s ponds have been lost.

The initial drive to restore wetlands in East Anglia was guided by a Norfolk farmer, Richard Waddingham, who began protecting his ponds at a time when his neighbors still were filling theirs in, says Carl Sayer, a researcher at University College London who worked closely with Waddingham.

Waddingham drew inspiration from a pair of U.S. bird biologists from Cornell University whose work centered on the importance of wetlands to breeding ducks.

Nick Anema describes how his view of farming differs markedly from his father’s, who regarded the natural world as an obstacle to overcome.

For Anema, farming and preservation are inextricably linked. Farm too intensively and it degrades the soil. Cultivate all the way up to the property line and there is no room for flowers that draw bees and insects to pollinate his crops.

He had been leaving the “shelter belts” that ring his crops untouched for years when in 2013 he saw an advertisement seeking farmers who would be willing to have ghost ponds on their property excavated as part of a research project.

He suspected a low point in one of this fields fit the description of a ghost pond and a check of old maps confirmed it. By the time the excavation wrapped up, water already was pooling at the bottom.

After ghost ponds are dug out, seeds from long-buried water plants come to life, including in one case a pond on Anema’s farm that had been filled in an estimated 150 years ago. And as the plants come back, so do the insects that depend on them, followed by fish and birds that eat the insects.

“We didn’t know what we would find in these holes in the ground until we started digging,” Sayer said. “They’ve done just what we hoped. They’re wonderful, healthy, vibrant ponds.”