Edaphic Gradients And Species Attributes Influencing Plant Distribution In Littoral Salt Marshes Of Qatar

Abstract

Edaphic gradients of moisture and salinity are critical environmental stresses that seriously influence littoral salt marsh flora, and determine the zonation of coastal vegetation. Shoreline communities subjected to severe salt stress consisted of salt avoiding C3 hygrohalophytes exhibiting syndromes such as halosucculence and salt secretion. Marsh communities further inland subjected to severe water stress during the dry season consisted of C3 xeromorphic winter annual species. Plants inhabiting the transition zones between the low and high marsh areas were subjected to a double stress consisting of seasonal water and salt stresses. These transition zones were strictly inhabited by species exhibiting the C4-syndrome. Structural and functional attributes associated with the C4-syndrome appeared to be crucial for the life of species in these transition zones. Electron transport and chlorophyll fluorescence studies showed that the C4 species of the transition zone possessed moderate tolerance to salt stress and a remarkably high degree of tolerance to water stress.