Factors influencing the soil salinity regime along an intertidal gradient

Abstract

The influence of estuarine waters and rainfall deficit on top soil (0–5 cm) salinity was investigated for 23 stations situated along an intertidal gradient sampled at monthly intervals over a 4-year period. Up to a level half-way between MSL (mean sea level) and MHW (mean high water) soil salinity was strongly correlated with fluctuations in inundation water salinity. On average, 80% of the variation could be explained by this single factor. The impact of the estuarine waters on sediment salinity decreased above this level and dropped below significance level at 58 cm above MHW. The correlation between the rainfall deficit over the 5 days prior to soil sampling and soil salinity was significant at site elevations of 4 cm below MHW and higher. These results suggest that functioning of salt marsh ecosystems occurring below MHW will not be affected by precipitation or drought.