Ghost Forest Researcher: All Along The Atlantic Coast, Seawater Steadily Pushing Salt Inland

[hatrack]

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Like all living organisms, trees die. But what is happening here is not normal. Large patches of trees are dying simultaneously, and saplings aren't growing to take their place. And it's not just a local issue: Seawater is raising salt levels in coastal woodlands along the entire Atlantic Coastal Plain, from Maine to Florida. Huge swaths of contiguous forest are dying. They're now known in the scientific community as “ghost forests."

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In 2016 I began working in a forested North Carolina wetland to study the effect of salt on its plants and soils. Every couple of months, I suit up in heavy rubber waders and a mesh shirt for protection from biting insects, and haul over 100 pounds of salt and other equipment out along the flooded trail to my research site. We are salting an area about the size of a tennis court, seeking to mimic the effects of sea level rise. After two years of effort, the salt didn't seem to be affecting the plants or soil processes that we were monitoring. I realized that instead of waiting around for our experimental salt to slowly kill these trees, the question I needed to answer was how many trees had already died, and how much more wetland area was vulnerable. To find answers, I had to go to sites where the trees were already dead.

Rising seas are inundating North Carolina's coast, and saltwater is seeping into wetland soils. Salts move through groundwater during phases when freshwater is depleted, such as during droughts. Saltwater also moves through canals and ditches, penetrating inland with help from wind and high tides. Dead trees with pale trunks, devoid of leaves and limbs, are a telltale sign of high salt levels in the soil. A 2019 report called them “wooden tombstones."

As the trees die, more salt-tolerant shrubs and grasses move in to take their place. In a newly published study that I coauthored with Emily Bernhardt and Justin Wright at Duke University and Xi Yang at the University of Virginia, we show that in North Carolina this shift has been dramatic. The state's coastal region has suffered a rapid and widespread loss of forest, with cascading impacts on wildlife, including the endangered red wolf and red-cockaded woodpecker. Wetland forests sequester and store large quantities of carbon, so forest die-offs also contribute to further climate change.

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https://bigthink.com/surprising-science/ghost-forests

[bucolic_frolic]

1. It varies species to species, but roots travel far and deep

so they can reach salt groundwater that is not apparent. I also submit that small trees, if they surround a large tree closely enough, together or single, can strangle the root system of larger trees. Must be a survival thing.

[FakeNoose]

2. I've read that groundwater is one of the problems

For example, Florida is flat and the population is dense in many areas. Taking water out of the ground for human use causes seawater to flow inland, due to osmosis. I'm not a scientist, but that makes sense to me. It's probably happening in coastal lowlands wherever groundwater is being pumped out faster than it's being replaced by seasonal rains.

[hatrack]

3. Last I read, the saltwater intrusion line around Ft. Lauderdale was six miles inland . .

Well fields nearest the coast already shut down or in the process of shutdown.

[BobTheSubgenius]

4. As you would expect, NC met these threats head-on with sensible, aggressive policies.

In 2012, the state whose low-lying coast lies in the path of Hurricane Florence reacted to a prediction of catastrophically rising seas by banning policies based on such forecasts.

This was published in The Guardian, and Stephen Colbert mocked the legislation and legislators during his show.