Jennifer Walker picked her way through the swamp, avoiding the muck while ducking under branches and climbing over felled trees.
To her left loomed one of the large "ghost forests" of the Jersey coastal plain: dead Atlantic white cedar trees, standing pale and bare at the edge of salt marshes.
Scientists such as Walker, a 25-year-old doctoral candidate at Rutgers University, are looking to the ghost forests as a potential indicator of rising sea levels, exacerbated by climate change.
"It's the first time I've been to one of these fringe marshes before," said Walker, who was in the 8,000-acre Dennis Creek Wildlife Management Area in Woodbine, Cape May County. "Getting near them can be difficult. I've seen the groves from the road and kayak."
Dead cedars and ghost forests are not new. Some have been around for decades. Walker's own work uncovered trees that died hundreds of years ago, sunk in muck — yet rot-resistant — along the Mullica River. New Jersey's coast has been "sinking" since ice sheets began their retreat at the end of the ice age.
But scientists are alarmed at the affect that rising sea levels and more frequent big storms could have on still-healthy cedar forests living between the Pinelands and coastal saltwater marshes. Salt water kills the Atlantic white cedar with a vengeance.
"It's accelerating," Walker said. "Now we are looking at sea level rise that's five times faster" than in the recent past.
The Atlantic white cedar, or Chamaecyparis thyoides, is native to New Jersey. Once, the state had about 115,000 acres of the trees. Now, there are likely about 30,000 acres.
Just to the left of Walker stood about 100 acres of dead trees, in jarring contrast to the almost cathedral-like healthy forest of Atlantic white cedar not far away.
The trees can live up to 300 years. A healthy stand grows so dense that it tends to shut out light, casting a dark, primeval feel onto the forest floor.
The trees were prized by colonists because they grow tall and straight, and their wood is light but durable. Because they thrive on lots of fresh water, the trees favor areas near or in swamps — which can be perilously close to saltwater.
The New Jersey Department of Environmental Protection has assessed the coastal impact of sea level rise, and expects more frequent and intense coastal storms, faster sea level rise, and more flooding.
Bill Zipse of the New Jersey Forest Service said the tree is so important to the state that "cedar restoration is part of our mission." In addition to its cultural and aesthetic significance, the Atlantic white cedar provides cover for certain species of animals, and its roots help filter impurities from the freshwater swamps. The state's efforts are directed farther from marshes to avoid the impact of storm surges and sea level rise.
Tom Doyle, deputy director of the U.S. Geological Survey Wetland and Aquatic Research Center in Louisiana, was part of a team that surveyed New Jersey forests after Hurricane Sandy. He said big storm surges can leave salt deposits long after water recedes.
Even after Sandy abated, salt water was still trapped inland, locked in by roads and other man-made features, said Bob Williams, who operates Pine Creek Forestry and manages about 130,000 acres of private land.
Atlantic white cedar saplings are starting to appear in forests that Williams is working to restore, including a property off Route 9 in Bass River Township, Burlington County.
"This is where the water pooled and ponded during Sandy," he said, stooping to reach for a sapling growing next to a felled log. "Route 9 blocked it, so the water could not flow back to the ocean. There was at least 18 inches of water."
Most of the salty Sandy water is gone. Under Williams' guidance, the property owner clear-cut an area of trees to allow sunlight to penetrate. As a result, the cedars are starting to grow naturally. The same is happening at other properties he has worked on in Burlington and Atlantic Counties.
But bringing back trees farther inland is easier, he said.
Closer to the coast, "those dying trees are not the cedar killed off by the Sandy surge," Williams says. "That's direct sea level rise. To me, there's nothing we can do for that. It's climate change."
Exactly how much the species has been diminished in recent years is hard to say. Researchers do not have a comprehensive survey of existing and dead Atlantic white cedar, and there is no coordinated assessment among federal and state governments and universities.
"Most people don't see it, and that's part of the problem," Zimmerman said of the ghost forests. "For those of us studying this tree, or who love it, it is a concern. We need a plan. You're going to need money, but it is tight."
Ken Able, a Rutgers professor based at the university's marine field station, recently stood on the edge of a swamp off the Nacote Creek in Port Republic, Atlantic County. One side was a good stand of cedar, bordered by a dying one. Both can be seen from the road. In fact, motorists rushing to the Shore this weekend can see glimpses of ghost forests from the Garden State Parkway, Routes 9 and 47, and other main roads.
"With sea level rise, the saltwater is moving upstream. I've spent a lot of time in kayaks and you can see [dead trees] all over," Able said.
"The question is: How long have the dead trees been there and how much is it accelerating?"