Dunes Aren’t Just For Sand Worms. Here’s Why They Matter on Earth.

Allyson Chiu in The Washington Post: The famed coastal dunes that inspired the shifting sand landscape of the desert planet Arrakis in Frank Herbert’s science fiction novel “Dune” are also under siege — from climate change and human development.

Like many beaches around the world, the vast sandy ecosystem that stretches along Oregon’s central coastline is threatened by sea level rise and more powerful storms. “There are a lot of places where dunes are eroding that weren’t eroding in the past,” said Sally Hacker, a coastal ecologist and professor at Oregon State University who researches the landforms. As communities build right up to their edge, disrupting the complex system of sand, these dunes can become even more vulnerable to coastal erosion. The rolling mounds lining beaches are more than just big piles of sand. Beyond providing critical habitats for wildlife and having the potential to sequester carbon, these structures help protect coastal communities from damaging storms — one main reason some cities and towns are investing heavily in restoring and constructing them. In Salisbury, Mass., for example, a local group spent more than $500,000 to build a protective dune that washed away in a matter of days after a strong storm pummeled the beachside town.

Here’s what you need to know about dunes.

What is a dune?

Dunes are sandy elevated landforms that typically have plants growing in them. They are often found along low-lying coastlines where strong waves and currents drive sand onshore to the beach. The grains get blown up the beach and landward where they are trapped by plants, gradually accumulating sand and building dunes over time.

Without plants, the stable hills of sand people recognize as dunes would not form. “It would be like the very open, shifting sand environment that you see on Arrakis,” Hacker said.

“It’s all about the root system underneath,” she added. “That network of roots stabilizes the dune and keeps it from eroding.”

Historically, much of the dunes in Oregon and Washington were sparsely vegetated mounds of loose sand. To keep the grains from blowing into and overwhelming nearby settlements, there was an organized effort in the early 1900s to systematically plant European dune-building grasses to stabilize the sand and create tall dunes. In the late 1950s, Herbert, then a journalist, took a trip to the dunes near Florence, Ore., where he would later draw inspiration from while writing “Dune.”

When vegetated dunes form naturally, the grains of sand also become packed tightly, making the mound more stable, said Alison Branco, climate adaptation director at the Nature Conservancy in New York. This slow process is “part of why a natural dune that has formed gradually is not the same as a big pile of sand that you might dump,” she said.

Why do we need dunes?

Aside from being recognizable features of picturesque beach landscapes, the sand structures are often the first line of defense for seaside communities against storms and rising tides. During storms, for example, dunes can block damaging winds and waves from reaching people or wildlife habitats behind them.

If left undisturbed, dunes would probably be able to hold their ground against rising water levels and extreme weather, Branco said. For instance, they can be flattened by storms and still rebuild themselves.

“If there were no people messing around with them, they would be very resilient to the impacts of climate change,” she said.

Dunes could also be a tool in the fight against climate change, said Hacker, who is researching dune systems and carbon sequestration.

More here.