Drivers of rhizosphere bacterial communities in Atriplex canescens across soil depth and growth stage in an extra arid region.

In the restoration of extreme arid desert ecosystems, plant-rhizosphere microorganism-soil synergy determines vegetation colonization and stability. This study focused on Atriplex canescens, divided soil into 0-20, 20-30, 30-40 cm layers, and explored spatiotemporal dynamics of its rhizosphere bacterial community and driving mechanisms. Results showed: ① Dominant phyla were Pseudomonadota, Actinomycetota, Bacillota, Bacteroidota (cumulative relative abundance >70%); Ralstonia was enriched in early growth period (EP), while Halomonas and Arthrobacter dominated middle (MP) and late (LP) periods. ② Significant spatiotemporal variation existed: temporally, α-diversity, network complexity and stability in MP/LP were higher than EP; spatially, bacteria enriched in root-intensive layers (20-30, 30-40 cm), with a "suitable microhabitat" in 20-30 cm layer during EP. ③ Growth period and soil depth synergistically regulated the community by altering spatiotemporal heterogeneity of soil nitrogen, dissolved organic carbon and pH, and nitrogen and dissolved organic carbon were core factors in root-intensive layers, while pH played a greater role in surface and deep layers. ④ The core regulatory chain: growth period and soil depth formed a two-dimensional framework, modifying root-intensive layer microenvironment to induce soil physicochemical heterogeneity, driving bacterial community differentiation and forming patterns adapted to Atriplex canescens at different growth stages. This study clarified the community's spatiotemporal dynamics and driving mechanisms, providing theoretical support for microecological regulation in desert restoration.