Establishment, development, and decline of Salix psammophila communities: Changes in soil conditions and floristic composition in dune slacks

Abstract

The Mu Us Sandy Land is a unique and sensitive dune system in northern China. Salix psammophila communities, as a natural large landscape in inland dune slacks, have seldom been investigated, especially the characteristics of their different developmental stages. Thus, in this study, we explored the differences in soil conditions, floristic composition, and vegetation types between developmental stages of Salix psammophila communities to protect natural shrubland in a semiarid ecosystem. We used transects and quadrats methods to investigate the communities. One-way analysis of variance was performed to detect differences in seed germination rates, species diversity, and edaphic variables among different developmental stages. Relationships between communities regarding species composition and edaphic variables were analyzed using the redundancy analysis. The results showed that the soil conditions required for seedling establishment included good soil surface moisture (water table 28–40 cm), lower saline alkalinity (soil saturation pH 8.7–9.0; soil electrical conductivity 29–40 μs/cm), sandy soil (coarse sand 57%–69%; fine sand 30%–42%), low C/N (6.19–8.58), and open spaces. Vegetation cover, soil moisture, saline-alkalinity, soil total carbon, soil total nitrogen, fine sand, and silt content increased, whereas coarse sand content decreased from the seedling to mature stages. Soil texture was a major driving factor in all developmental stages. We concluded that Salix psammophila seedling recruitment was related to dune mobility (where bare damp blowouts are newly created by wind) and aquatic–terrestrial areas. Optimal conditions for colonization by Salix psammophila communities included fresh, open, bare, and moist sandy soil.