California has lost roughly 60% of its coastal dunes since the mid‑1800s, according to a newly published statewide analysis that used historical maps, aerial photography, and LiDAR to track dune change over time titled “Significant Coastal Dune Loss Challenges California’s Climate Resilience and Biodiversity Goals.” Researchers found that more than 440 square kilometers of dunes have disappeared, largely replaced by roads, neighborhoods, and other development. Remaining dunes are increasingly fragmented, reducing habitat quality for species that depend on open sand, including the western snowy plover and least tern.Along the North Coast, those pressures are visible today as steep sand scarps form along Samoa and other beaches, carved by powerful winter waves and long‑term erosion. Danny O’Shea, who recently retired after 10 years as a lecturer in the oceanography department at Cal Poly Humboldt, said the sharp cliffs now lining parts of the shoreline are a direct result of seasonal storm energy.“That’s caused by winter storm wave erosion,” O’Shea said. “It’s got nothing to do with the beach grass or anything else. Everything to do with the storm wave erosion.”Humboldt County’s dunes, including the Lanphere, Samoa, and Ma‑le’l complexes, are among the largest intact systems left in the state. They exist only where three conditions align: a low‑lying coastline, steady onshore winds, and a reliable sediment supply from the Eel and Mad rivers. O’Shea said those factors make the region’s dunes both dynamic and ecologically significant.“These are large, dynamic dune fields,” he said. “They’re constantly responding to wind, waves, and sediment movement.”Suzie Fortner, executive director of Friends of the Dunes, said Humboldt County’s coastline contains roughly 30 miles of dunes. The region has experienced far less dune loss than other parts of the state, she said, making its conservation value especially significant.“We have one of the largest intact dune systems on the California coast,” said Fortner. “And our dunes here in Humboldt County are even more unique because our vegetation type is much different than other dunes in California.”“What recent research has found is that a restored dune system is more resilient to these erosional events. It doesn’t mean that erosion doesn’t happen. Erosion is going to happen no matter the type of vegetation we have,” said Fortner. “But when we have native plants dominating the foredune rather than the invasive beach grass, that foredune can recover more quickly from the erosional events. Sometimes two years faster than a dune dominated by European beach grass, and that allows sand to re-enter the system and replenish the dune system, which is what we want to see. Our restored dunes are filled with diverse vegetation. They’re blooming, full of pollinators; it’s not a bare landscape.”Read Original Article
