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Bad Weed 

Or is it? The case for not yanking out every invasive plant in our dunes

The prevailing wind flows over the ocean, pushing water across its surface. As it sweeps ashore, the wind crosses the wet slope then hits the beige edge of dry sand, lofting millions of grains and urging them southeastward. The papery sound of the sand grains as they tumble plays high counterpoint to the low splashy roar of the surf.


Now, here is the question:

Do we want our whispering sand grains to hit a wall of rigid, tall, pointy dunes anchored by European beach grass, Ammophila arenaria, and be absorbed into the small spaces within that long, golden mane?

Or do we want them to bounce into a broader undulation of shifting dunes, absent Ammophila, where pulsing sand drifts interlace with multicolored mats of low-lying native plants that have diversified because of the very harshness and competitiveness of the environment: sagewort, dune tansy, beach strawberry and seathrift; buckwheat, beach pea, miner's lettuce, yellow sand verbena and the endangered beach layia with its small white flowers?

At first the answer seems obvious: the pretty scenario, the multicolored one. That's what we want. Get rid of the dominating exotic beach grass, introduced to so many beaches by our forebears to protect railroads and roads and town from sand drifts. Bring back diversity! Decades of eager volunteers and dutiful prison crews trooping out to the dunes to rip the offending alien out can't be wrong.

But for some folks -- perhaps a minority, but a vocal and compelling one -- that invasive beach grass has its place.

So who gets to decide the question of how we direct our sand grains, what plants we allow to exist? And is there only one "right" answer?


In this 40-acre patch of dunes in the California State Park system's Little River State Beach -- on the north end of Clam Beach, north of Arcata about 10 miles -- the sand seemed to flow especially easily, sheeting across the vast, almost plant-free landscape.

Uri Driscoll and Bill Weigle, avid horsemen, stood at one corner of these dunes -- and it literally was a corner, defined by an orange-and-black rope "fence" staked out around the perimeter. It was early April. Over the past 30 years, both men had regularly ridden their horses on a well-established trail through here. They're none too happy about changes in recent years: the large-scale bulldozing project, to get rid of Ammophila arenaria, that had denuded the place; the rope fence that recently went up and that spooked their horses; the fact that their old horse trail now disappeared into a sand drift not far down the beach; and recent enforcement of a ban on horses, even though a previous superintendent of the state parks had said they'd be allowed to ride here.

Driscoll and Weigle looked at the machine-altered sandscape beyond the rope fence. The stiff, hummocky dunes that the grass had anchored in place had loosened up and been picked apart by the wind. Nothing but dead-grass stubble and some emerging lines of re-sprouting beach grass, now. The idea was that native plants would come in, eventually. A small sign attached to one of the rope-fence posts with a picture of a bird on it said: "Temporary Closure. Snowy Plover Habitat. Snowy plovers are protected by the federal Endangered Species Act. Your cooperation is appreciated." At the bottom of the sign were the logos of six agencies, mostly state and federal.

"They call this snowy plover habitat?" said Driscoll, scoffing. "It looks like a bomb went off. And now you can't go in an area we used to enjoy."

Driscoll has been scrutinizing the management plans for this and the adjacent county-managed Clam Beach for years now, questioning some of the management activities done in the name of saving Western snowy plovers. He points to reports by certain researchers, including some in the wildlife department at Humboldt State University, that indicate Clam Beach is not a prime plover nesting site, that windblown sand, and predators such as ravens, affect plovers more than people, and that the benefits of restoration haven't yet proven to be beneficial to plover reproduction. Driscoll said there's even one place in Oregon where Ammophila is considered "prime plover habitat."

"Truth is, I don't think anyone knows yet what prime plover habitat is," added Weigle.

"And the whole plover issue is more complicated than just the Ammophila side of it," said Driscoll.

"But it's been the primary reason given for removing it here," said Weigle.

Driscoll imagined the worst-case scenario: Windblown sand would blast away any native plants trying to get re-established, as well as discourage plovers, and the lowered dunescape would be susceptible to high surf that could wash in and inundate the wetlands behind the dunes with salt water.

Or, said Weigle, a botanist and director of Humboldt State University's greenhouse, perhaps the removal of Ammophila would simply stimulate it to grow back more vigorously; he'd seen it happen elsewhere. And even here, where it was bulldozed and buried deep, there were new shoots coming up. "Ammophila is here to stay," he said. "It's always going to take machines, labor or chemicals to try to maintain it. And I kind of wonder, where is the next 50 years of funding coming from to keep this project going? You really can't go out and do this entire beach. You have to pick some of the more doable habitats and work on those for maintaining refugia."


Earlier that same day, on the Samoa Peninsula, Manila resident Dan Edrich had walked the short distance from his house into the Manila Dunes Recreation Area behind the Manila Community Center. These dunes had been his stomping grounds for many years.

The Manila Community Services District bought the 140-plus-acre dune area in 1991 and eventually began restoration work -- hand removal of invasive beach grass, Yellow bush lupine (which added nitrogen to the fixed dune sand, enriching it more than native plants could tolerate) and ice plant. The work was concentrated mostly in the foredunes, closest to the ocean, where the dunes would naturally have been less stable prior to the introduction of beach grass. The weeding had left open patches of sand interspersed with low clumps of native plants, which the restorationists said would eventually grow into the ideal dune mat.

Edrich wasn't impressed. He said that now that the 30-foot foredunes were destabilized they would shrink in height and make residents of Manila more vulnerable if there was a tsunami -- and that FEMA might have a problem with that alteration. The forested wetlands, he added, that had formed behind the grass-stabilized dunes, where the sand over time had been scoured away to the groundwater table, would be inundated with sand, and with salt water in high surf -- and since the Manila Community Services District had bought the dunes with a wetland habitat conservation grant, that could be a problem, too. Also, he claimed, the water main that comes from the Mad River to the peninsula and then splits off to go under the bay to supply the Eureka area had become exposed in places after a round of grass pulling.

Weed-pulling also occurred in an isolated spot in the dunes closest to town, the "backdunes." Edrich actually ran out one day to stop it. He said that work has resulted in blowouts, with re-mobilized sand now creeping toward town; the little lookout by the community center was already engulfed.

Saddest of all, to Edrich, was what happened to the trees in some middle dunes. "You see this tree?" he said, pointing out a stick that used to be a living, squat, native pine, not far from the floundering lookout. He walked along, pointing out other small dead or dying pines. "This whole pygmy forest is dead."

Removing the grass and its long rhizomes that had anchored the sand and pulled water into it had caused the dunes to dry up, parching the little pine trees.

"The damage is incredible," Edrich said. "Things were going fine until someone came by and said, 'You've got weeds, and we need to pull 'em.'"

Edrich was actually on the MCSD Board when the agency devised the management and restoration plan. The subsequent negative declaration saying there wouldn't be significant environmental impacts avowed there would be no changes in geologic structures. In 2007, Edrich paid Busch Geotechnical Consultants to determine if trails and invasive plant removal were contributing to dune erosion in the backdune area by the community center. They concluded they were, and recommended several fixes: signage keeping people off unofficial spur trails, replanting backdunes, and so forth.

Edrich sued the district in 2008, claiming it had violated the California Coastal Act by not revegetating pulled areas and for pulling plants out of the backdunes, among other things. Both an MCSD spokesperson and Edrich said last week they're close to settling the suit -- perhaps even this week.

Whatever the outcome, Edrich sounds soured on restoration work and questions the motives of groups such as Friends of the Dunes, which gets grants and contracts to organize weed-pulling events at various Humboldt dunes, including at Manila. The general rule is that it costs about $35,000 an acre to pay a jail work crew, or the equivalent in volunteer hours, to pull weeds.

"I think Friends of the Dunes is using the MCSD as a grant mill," he accused.


Nobody actually denies that pulling out invasives, especially Ammophila arenaria, destabilizes a dune. That's the whole idea. But the concept can be confusing. People planted the beach grass long ago to stop sand from moving inland; now they want to reverse that? The Humboldt Dunes Cooperative hosted a forum a couple of Fridays ago at the Manila Community Center to educate attendees on the ecological, geological and restoration factors influencing local dunes, and to examine the relationship between people and dunes and how best to manage dune systems given their particular constraints. Ammophila featured heavily in the discussions.

All over the world people have planted beach grass, said Patrick Hesp, a geography professor at Louisiana State University and internationally renowned dunes and coastal management expert. Now this single species, so good at edging out other plants, dominated dunes everywhere and prematurely stabilized them. Geomorphologist Bill Weaver, an adjunct professor at HSU and president of Friends of the Dunes, and geologist Tom Leroy of Cascadia Geosciences, each explained how the Samoa Peninsula contains several ages of relic, stabilized dunes, the oldest arising perhaps as much as 14,000 years ago and the youngest forming after a huge earthquake about 300 years ago. But they stabilized over a long time period, and forests formed on them that eventually were taken over by new moving dunes.

The current foredunes -- in Manila on the Samoa Peninsula, for instance -- were stabilized by Ammophila, introduced in the last century. They're tall, narrow and steep and easily eroded by the surf. They could be overwashed by a locally generated tsunami. In the case of such a tsunami, said Leroy, the higher backdunes, not these foredunes, would be the best defense.

The overall consensus of the panelists was that removing Ammophila from the foredunes to restore a native process was an overall good aim for our dune systems. Broader foredunes would form. And you'd have more diversity of plants and of native creatures that depend on them, such as solitary bees, said Andrea Pickart, the Humboldt Bay National Wildlife Refuge System's ecologist for the Lanphere Dunes ecological reserve, north of the Manila Dunes.

But, Pickart and Weaver both said that in some places land managers might not want to pull the beach grass from their backdunes.

A few days after the forum, Pickart and Weaver wandered into the dunes behind the Manila Community Center (it isn't Pickart's official domain, but she knows the dunes here well). Pickart explained that, out at Lanphere, their goal is to remove all the weeds to restore the natural processes: let dune mat form everywhere, and let the parabolic backdunes, formed so very long ago, slowly overtake the lovely forest. There was no town to endanger with sand-engulfment.

"Here in Manila, there are more constraints," she said. "The old Manila management plan says to turn everything into native dune mat. But we're now recommending forest restoration for the parabolic dunes, the dunes closest to town. We certainly wouldn't want to restore natural processes in these backdunes."

Pickart said they could plant trees right in the beach grass, on these backdunes, where trees had been before people cut them. The forest would grow and outshade the Ammophila. In the foredunes, Weaver added, the dune mat would come back well on its own. But, he admitted, it would probably make sense for Friends of the Dunes volunteers to start revegetating the foredunes, as well, if only to curb the impression that all they did was yank plants out. "And so people know the objective isn't completely open sand," he said.

Walking past Dan Edrich's sad little dead pine trees, however, between the backdunes and foredunes, Pickart said they'd only grown there because Ammophila had been there, trapping water in the sand for them. So it made sense they'd die when the grass was pulled.

But she said it matter-of-factly, not meanly. She wasn't against plants growing where they weren't expected -- even exotic species, in some cases. Why, out at Lanphere Dunes, Humboldt's proudest example of a dune system and forest thriving under natural processes, 40 percent of the species on the official Lanphere Dunes "species list" are exotics.

"And those are all fine," said Pickart. "We let them be. If it's an exotic and it's fitting in, if it's not disrupting things, we leave it alone. Like sea rocket -- it's an exotic species, but it's not invasive."


The dune system of the Humboldt Bay region, fed sand from the Eel and Mad rivers, extends 34 miles between Moonstone Beach in the north down to Centerville Beach, past Ferndale. Some pieces of it are public, some are privately owned. Some allow more human activities than others. And in each piece, the managers decide what to do with their plants and their sand grains.

At Manila Dunes, they'll likely end up leaving some of the invasive Ammophila arenaria, and yanking some of it. In more protected areas, such as Ma-le'l and Lanphere dunes, north of Manila Dunes, it's been a steady goodbye to all invasive (but not all exotic) species by careful handpulling, and hello to old-time sand movement. And at Little River State Beach, one of the most aggressive methods of beach-grass removal has been underway for several years.

Bill Weigle and Uri Driscoll, walking along the bulldozed and bladed dune area at Little River State Beach, talked some about this. Weigle said what they'd done out at Lanphere was great, and manageable -- they were fighting Ammophila off at the edges by handpulling it. Driscoll said he wished you didn't have to jump through hoops, though, to go there -- if you want to visit Lanphere you first have to go on a guided walk to learn the trails, and then you can get a permit.

Weigle agreed he didn't want the agencies to overly guard all of the beaches and dunes.

"This beach is a great place," Weigle said. "There's a lot of interesting stuff going on here. We ride our horses through here, and there's pools that form and we see the geese and the ducks that come in, and the herons and the night herons and the egrets. So there is a lot of diverse wildlife and habitat."

Now, though, that could disappear, Driscoll added. Already a high surf had washed over the machine-flattened dunes and flooded the wetlands with saltwater -- which couldn't be good, he said.

"I'm totally for restoration," Driscoll said. "But this is a joke."

Michelle Forys, an environmental scientist with California State Parks in charge of the Little River State Beach restoration project, takes exception to this characterization.

On the phone recently, Forys said the restoration at Little River isn't finished, and it could take a very long time to reach the goal of a continuous native dune mat.

"It's not going to be a void of sand forever!" she said.

Even now, though all flat and sandy, plovers had been seen hanging out in it. As for the concern about saltwater polluting the wetlands, she said none of those wetlands are freshwater. "They're on sand -- which has salt in it."

The restoration here began in 2005 with a pilot project to test different beach grass removal methods in the foredunes -- to see how much the grass came back, and to see how well native species established themselves. On two plots they had tested the use of just an excavator to pluck out beach grass, then dumped the sand and grass onto the grassy backdunes. On two more plots they had used a bulldozer, and again piled the sand and pulled grass onto the backdune. On yet two other plots they had used the bulldozer, then buried the pulled grass with clean sand so it wouldn't resprout. Two final plots were left alone, as controls.

The bulldozer/bury combination worked best, so in 2009 they did more of that on about 31 more acres, following up with regular handpulling of the beach grass that does come back. She said they seeded and transplanted native species on some acres, and would do more of that if they had the money. The project so far has mostly been paid for with money from a mitigation fund set up after a dredge vessel spilled oil in Humboldt Bay in 1999, and some grants.

Even without extensive reseeding, said Forys, a native dune mat would grow here. It could take a long time, more than five years, but it would start to come back, especially if they didn't disturb the backdune (they would leave the beach grass there, for now). And she said the Ammophila control would not be a perpetually huge chore, the way Weigle foresees it.

"We'll probably have to do one handpulling treatment a year," she said. "But that could be just one ranger, walking through. It would go quickly. But yeah, we'll have to hold the line."

They plan to do 30 more acres of foredunes, all the way up to the north parking lot at Clam Beach -- where the tall, brushy, golden cornfields of European beach grass will resume, because Humboldt County Parks has no plans to remove it.



The prevailing wind flows off the ocean, sweeps ashore and lofts the dry, beige sand. Some of the grains settle into tall, scruffy peaks yellowed with thick grass. Some tumble onto broad humps, bounce off sturdy little dune plants then melt into rivulets of sand. Is one way right, the other way wrong? Depends on whose beach you're on.

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About The Author

Heidi Walters

Heidi Walters worked as a staff writer at the North Coast Journal from 2005 to 2015.

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