Species zonation in Corroios salt marsh in the Tagus estuary (Portugal) and its dynamics in the past fifty years

The objective of this study was to understand the main factors controlling salt marsh plant species structure and dynamics. So, we determined plant cover and composition across a permanent transect, 450 m long and 1 m wide, defined in 1951 in Corroios salt marsh, in the Tagus estuary (Portugal) and we characterized the physicochemical variables every 50 m along this transect. Based on those results we discuss the dynamic and evolution of salt marsh vegetation during the last 50 years comparing former and recent data. The results showed that differences in salinity and flooding were determinant factors in plant species composition and distribution along the studied transect. In addition, long-term variations of these factors as a consequence of vertical accretion and sea level rise seem to be responsible for the evolution in plant structure and vegetation zonation patterns, during the last 50 years in the Tagus estuary salt marshes.