Abstract: To assess the spatial distribution of soil salinity and correlations among different indices of salinity in the Yellow River Delta, an investigation of vegetation quadrats and soil samples was carried out by using the classical statistical and variance analysis in October, 2012. It was shown that soil salinity in the study area belonged to heavy salinity, as salt content was above 4.0 g^.kg^-1. There was a clear gradient in soil salinity in the order of Tamarix chinensis community>Suaeda salsa community>Phragmites australis community>cotton community. Vertically, soil salinity increased with soil depth in Suaeda salsa and Tamarix chinensis communities, while the soil salinity was the highest in the sub-surface soil in Phragmites australis and cotton communities. Variable coefficient of soil salinity in the study area was mostly moderate, yet there was a strong spatial variability of individual ions, such as SO42- in Tamarix chinensis community, and Mg²⁺ and Cl^- in Phragmites australis community in the horizontal direction, CO32- in the Suaeda salsa community in both horizontal and vertical directions, and CO32- in the cotton community in vertical direction. In 0-80 cm soil layer, the concentrations of K⁺,Na⁺,Ca²⁺,Cl^- and HCO3- were significantly (P<0.05) different among plant communities, while Mg²⁺,SO42- and CO32- showed no significant difference. Contents of Cl^- exhibited a significant (P<0.01) correlation with soil salinity. Therefore, controlling or reducing Cl^- input might be an optional approach to alleviate soil salinization in the wetland of Yellow River Delta.

Key words: Yellow River Delta, plant communities, soil salinity