The ecological restoration techniques that combine grazing, sand barriers with willows, fertilization, artificial planting, and continuous management are increasingly adopted in the management of flowing sandy land in high-altitude and cold regions. However, few studies have focused on the long-term ecological restoration effects of such technologies. This study systematically compared the vegetation and soil characteristics under different ecological restoration durations (0 (CK), 3 (F1), 14 (F2), 26 (F3), and 46 (F4) years) in the alpine sandy land of northwest Sichuan. The results showed that, with the increase of ecological restoration durations, (1) the aboveground and underground biomass of plants, and species number significantly increased, while the shannon-wiener index, margalef index, and simpson index dramatically decreased; (2) in the early stage of ecological restoration (0–3 yr), Cyperaceae accounted for the main groups, while in the late stage of ecological restoration (14–46 yr), Leguminosae and Forb groups predominated; (3) ecological restoration durations significantly influenced the total phosphorus (TP) content at a soil depth of 0–60 cm, but soil organic carbon and C/P ratio were only significantly impacted at 40–60 cm; (4) the plant and soil characteristics of F1, F2, and F3 treatments were more similar, and CK and F4 treatments were clearly distinguished on PC1 of principal component analysis; (5) there was no significant correlation between Leguminosae groups and environmental factors. Instead, a correlation between total nitrogen (TN) and Forb groups, Gramineae groups, and Cyperaceae groups was revealed. TN was very significantly positively correlated with species diversity and TP. Long-term ecological restoration improved plants biomass, plant species diversity, functional plant groups, and increased soil TP content in the alpine sandy land of northwest Sichuan.

This study comprehensively analyzes the physical and chemical properties of soil across different layers under Salix paraplesia shrubs, comparing these properties inside and outside the shrub canopies. It also examines species diversity and community stability in these areas, discussing the impact of soil from resource islands at different formation stages on vegetation restoration. Focusing on Salix paraplesia shrubs over varying restoration periods (45 years, 25 years, and 13 years), with unrepaired mobile sandy land serving as the control, the results are as follows: (1) As vegetation restoration progresses, the content of soil organic matter (SOM) and alkali-hydrolyzable nitrogen (AN) significantly increase. After 45 years of restoration, SOM and AN contents are 250.08 % and 442.43 % higher than in the control. SOM, AN, and total phosphorus (TP) contents are greater under the shrubs than outside the canopies, indicating pronounced fertilizer accumulation. (2) The number of plant species increases during the restoration process, with 18 more species present after 45 years compared to the control. Community diversity is highest after 13 years of restoration, with greater overall diversity outside the canopies than under the shrubs. These differences decrease as restoration progresses. (3) The stability of Salix paraplesia shrub communities is higher outside the canopies compared to under the shrubs. As restoration proceeds, stability differences between these areas diminish. The Euclidean distances for community stability outside and under the canopies are 13.97 and 14.68, respectively, after 45 years, indicating relative stability. (4) In the early stages of restoration, soil carbon (C) and nitrogen (N) significantly impact species diversity, while in the later stages, phosphorus (P) content becomes more limiting. Resource islands enhance plant community stability and vegetation restoration, playing a crucial role in ecological protection and vegetation restoration in the alpine sandy land of the Yellow River's upper reaches.