Does Soil Pore Water Salinity or Elevation Influence Vegetation Spatial Patterns along Coasts? A Case Study of Restored Coastal Wetlands in Nanhui, Shanghai

Abstract

Soil pore water salinity is widely accepted to be the primary influencing factor determining coastal vegetation succession. This study investigated an ecological wetland restoration process on the Nanhui coast, Shanghai, during which seasonal changes in vegetation density, soil salinity, and coastal elevation were recorded in detail. These variables interacted with each other and showed coincident distributions. The whole restoration process was categorized into four periods according to vegetation community dynamics. Regression analysis revealed that elevation, not soil pore water salinity, was the most critical factor influencing the spatial pattern of vegetation survival, expansion, and extinction on the Nanhui coast. From a long-term perspective, the local vegetation extinction pattern may have an irreparable influence on salt marsh succession, especially in environments with intricate hydrological and sedimentary conditions such as the Nanhui coastline. Without intact vegetation communities, deficiencies in coastal ecosystem resilience may cause vegetation extinction under the influence of a strong hydrological environment. The area between vegetation communities and bare tidal flats, the “vulnerable zone”, was a critical area determining the ultimate success of coastal vegetation restoration.