Coastal squeeze of vegetation zones in the Los Cerritos Wetlands: The effect of sea level rise

Abstract

This project assesses the elevation of several vegetation zones of the Los Cerritos Wetlands in Southern California to determine the possible effects of sea level rise on the salt marsh vegetation, the foundation of coastal salt marsh ecology. Steamshovel Sough in the Los Cerritos Wetland contains ideal habitat for the project. This coastal salt marsh is unique in that it abuts artificial elevation gradients of urban development on all sides. The confined nature of the wetland restricts its ability to adjust to future sea levels, a process known as coastal squeeze, which calls the sustainability of this scarce ecosystem into question. In-situ surveying of indicator species Parrish's Glasswort and Pacific Cordgrass (Arthrocnemum subterminale and Spartina foliosa) revealed the habitat elevations above sea level. Modelling various sea level rise scenarios using the habitat ranges determined through in-site surveying reveal expected future habitat zones. Los Cerritos Wetland has a notable susceptibility to sea level rise because of topographic convolutions created by local urban development. One and two foot sea level rise scenarios project substantial zone shifts resulting in pronounced winners and losers. The results here highlight the delicacy of the marsh and its intimate relationship to sea level, and hold a powerful utility to restoration project managers seeking to create a salt marsh that reflects the natural distribution of various habitats and which possesses longevity in the face of the changing environment.