Loss of Coastal Strand Habitat in Southern California: The Role of Beach Grooming

Abstract

We investigated the role of beach grooming in the loss of coastal strand ecosystems. On groomed beaches, unvegetated dry sand zones were four times wider, macrophyte wrack cover was >9 times lower, and native plant abundance and richness were 15 and >3 times lower, respectively, compared to ungroomed beaches. Experimental comparisons of native plant performance were consistent with our survey results: although initial germination was similar, seed bank, survival, and reproduction were significantly lower in groomed compared to ungroomed plots. Rates of aeolian sand transport were significantly higher in groomed plots, while native plants or wrack placed in that zone reduced sand transport. Our results suggest beach grooming has contributed to widespread conversion of coastal strand ecosystems to unvegetated sand. Increased conservation of these threatened coastal ecosystems could help retain sediment, promote the formation of dunes, and maintain biodiversity, wildlife, and human use in the face of rising sea levels.