Objective To explore the ecosystem carbon storage under different plant configurations, and provide scientific basis for improving the ecological environment and enhancing carbon sink potential in the arid and semi-arid regions of northwestern China.

Method Based on drought-resistant and carbon sequestering shrubs and herbs screened from preliminary experiments, six different plant configuration modes were designed using the principles of niche complementarity and functional synergy. A plant community construction experiment was conducted in a mining dump site to investigate the carbon storage and carbon sequestration effects of these configurations.

Result (1) The biomass carbon storage of different plant configurations ranged from 2.63 to 3.24 t/ha, which was 1.56 − 1.93 times that of the control plots. The soil carbon density significantly increased (5.98 − 8.67 kg/m², P < 0.05). (2) The three plant configurations with the highest ecosystem soil organic carbon (SOC) storage were Caragana korshinskii + Astragalus laxmannii + Medicago sativa + Agropyron elongatum + Setaria viridis; Amorpha fruticosa + Caragana korshinskii + Lespedeza bicolor + Melilotus officinalis + Agropyron elongatum + Setaria viridis; and Lespedeza bicolor + Caragana korshinskii + Astragalus laxmannii + Medicago sativa + Elymus dahuricus + Setaria viridis, with values of 11.62, 11.32, and 10.68 t/ha, respectively. Compared to the control, these configurations increased SOC storage by 44.87% − 71.08%, with an average increase of 56.95%. (3) All plant configurations functioned as carbon sinks, with sequestration intensities ranging from 1.41 to 2.20 t/ha. On average, carbon sequestration increased by 51.38% across all treatments.

Conclusion During ecological restoration, scientifically designed plant configurations based on niche utilization can effectively enhance SOC density and strengthen the carbon sequestration capacity of ecosystems, achieving the dual goals of ecological restoration and carbon fixation.