Distribution pattern and influencing factors of soil salinity at Tamarix cones in the Taklimakan Desert

Aims The Tamarix cone is a coppice dune, which is a specific bio-geographical phenomenon in the Taklimakan Desert, helpful for stabilizing and maintaining the structure and function of desert ecosystems. This study aims to investigate the soil salinity of Tamarix cones at different sites.Methods Tamarix cones were selected to investigate the spatial variations of soil salinity. Soil samples (0- 500 cm) were collected for soil pH, and electrical conductivity (EC), HCO₃ ^-, Cl ^-, SO₄ ^2-, Ca ²⁺, Mg ²⁺, K ⁺ and Na ⁺ content analysis.Important findings 1) From Qiemo to Aral, Qira and Tazhong, soil pH generally increased, soil litter content decreased first and then increased, soil electrical conductivity (EC), Na ⁺, Ca ²⁺, Mg ²⁺ and SO₄ ^2- content decreased, and K ⁺、Cl ^-、HCO₃ ^-content had no obvious change. 2) For the distribution layer, salt accumulation in the upper soil was significant within the Qiemo and Qira of Tamarix cones, and within the Aral and Tazhong, there was a significant pattern of salt accumulation along the soil profile. However, with increasing soil depth, soil pH generally increased and soil litter content decreased, soil EC at Qiemo and Qira generally decreased, and soil EC content showed the trend of decrease-increase-decrease at Aral, and the trend of increase-decrease-increase at Tazhong. 3) Correlation analysis and principal component analysis showed that soil litter content, SO₄ ^2-, K ⁺ and Na ⁺ content mainly affected soil salt content at Qiemo, where soil salt was mainly composed of sulfate. The major ion was Cl ^-, Na ⁺at Aral, Cl ^-, Na ⁺ and K ⁺at Qira, and Cl ^-, Na ⁺, Ca ⁺ and SO₄ ^2-at Tazhong. Therefore, soil salinity at Tamarix cones had an obvious spatial variability among different habitats. Soil salinity variation at Tamarix cones were closely related to the intensive evaporation, wind erosion, groundwater depth, litter content and the salinity of Tamarix chinensis, which was the key factor affecting the distribution of soil salinity at different sites.