Tamarix chinensis Lour. cultivation drives microbial succession and network reconfiguration in saline-alkali soil restoration

Long-term cultivation of the halophyte as an effective phytoremediation strategy for saline-alkali soils. In this study, soil samples were collected from plots planted with Tamarix chinensis Lour for 5 years (CL5Y), 10 years (CL10Y), and 20 years (CL20Y) at the Experimental Base for Efficient Utilization of Saline-Alkali Land Resources, Chinese Academy of Sciences. An unplanted plot was designated as the control (CK). After two decades of continuous planting, soil total salt content and electrical conductivity decreased by 83.7% and 82.9%, respectively, while key nutrient indicators showed marked increases—organic matter increased by 103.7%, available phosphorus by 986.8%, and alkali-hydrolyzable nitrogen by 127.6%. These substantial shifts collectively indicate a significant improvement in soil quality, with salinity strongly suppressed and fertility substantially enhanced. Soil microbial communities exhibited clear temporal succession in response to planting duration. Short-term (5-year) cultivation significantly enriched functional taxa involved in nitrogen cycling, such as Proteobacteria and Rozellomycota . Medium-term (10-year) planting resulted in peak bacterial α-diversity, with the abundance-based coverage estimator (ACE) index increasing by 20.9%. Long-term (20-year) planting fosters the development of a more complex and robust microbial co-occurrence network. β NTI analysis revealed that deterministic processes increasingly dominated microbial community assembly over time. This study underscores the pivotal role of plant-microbe interactions in mediating soil reclamation, thereby providing a scientific foundation for ecological restoration of saline-alkali lands.