Coastal Dune Habitat Restoration Projects: Why is Dune Restoration Important?
Dunes are dynamic interfaces between the land and the sea. From afar, they appear somewhat barren landscapes of seemingly endless undulating mounds of sand, but, in reality, they teem with life. The ecologically precarious species, western snowy plovers(Charadrius nivosus nivosus), listed as federally threatened, nest at the oceanward edge of dunes, moving further inland at times for foraging. Federally endangered plants such as Tidestrom's lupine (Lupinus tidestromii) and beach layia (Layia carnosa) flourish in some of the interdunal basins within this otherwise seemingly arid landscape. Rare butterflies such as Myrtle's silverspot (Speyeria zerene myrtleae) forage on delicate violets and other vegetation within their midst. All in all, this unique habitat supports 11 federally listed plant and animal species.
Unfortunately, as with many other unique habitats in California and the coast of the U.S., dunes have been tremendously impacted. Homes and businesses have been built to the edge of the sea. Where dunes remain, they have often been artificially stabilized by vegetation and fencing to prevent migration and impact to adjacent homes, businesses, farms, and ranches. Many of the plants brought in to stabilize dunes come from elsewhere and, once introduced, these non-native species spread rapidly, slowly encroaching into and eventually ousting the native plant species adapted to this environment—many of which have subsequently become threatened and endangered and are even on the brink of extinction. Some of the most common species planted to stabilize dunes are European beach grass (Ammophila arenaria), and iceplant (Carpobrotus spp).
Not only do these non-native species displace rare and common native plant species, but, because most of these species form dense colonies, they actually retard the natural process of dune movement or migration. In natural communities, dunes continually move in response to wind pressure and wave action, typically forming morphologically and floristically distinct smaller foredune and slightly larger backdune communities. These dune systems are often characterized by relatively flat corridors between dunes that allow for movement of many animal species, including snowy plovers, and "slacks" or depressional basins where groundwater and precipitation form an aquatic oasis. Non-native species and their deep root and rhizome systems act to armor dune systems and prevent natural migration, which leads to overly large foredunes and backdunes, an impoverished native vegetation community, and a substantial decrease in value of this system to wildlife.
coastal dune habitat restoration projects include: