Mechanisms of Microbial Community Succession and Functional Network Reconfiguration Induced by Long Term Tamarix chinensis Lour. Cultivation in the Ecological Restoration of Saline-Alkali Soils

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 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 20 years of planting, soil total salt content and electrical conductivity decreased by 83.7% and 82.9%, respectively, while key nutrient indicators including organic matter, available phosphorus, and alkali-hydrolyzable nitrogen increased markedly. 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 alpha-diversity, with the ACE index increasing by 20.9%. Long-term (20-year) restoration promoted the development of a highly complex and modular co-occurrence network, featuring enhanced positive interactions and greater network robustness. beta-NTI analysis further revealed the increasing dominance of deterministic processes in microbial community assembly over time. These findings underscore the critical role of plant-microbe interactions in mediating soil reclamation, providing a scientific basis for microbiome-assisted management and ecological restoration of degraded saline-alkali ecosystems.