Abstract: We analyzed carbon (C), nitrogen (N), and phosphorus (P) contents and their stoichiometric characteristics of sandy soil in four restoration patterns after 5 years restoration in the northwest Sichuan, China, including planting grass alone (PG), planting shrub alone (PS), shrub-grass intercrop (SG), and shrub-herb intercrop (SH). The untreated sand land was set as control (CK). The results showed that soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), C/N, C/P, and N/P were increased under different restoration patterns, especially under shrub-grass intercrop (SG). In 0-10 cm and 10-20 cm soil layers, the contents of SOC and TN under SG were significantly higher than that under other patterns. In 0-40 cm soil layer, the SOC storage under SG was higher than that under PG, PS, SH, and CK by 13.4%, 15.6%, 17.1% and 43.2%, respectively. The available N, available P, available K, and water content were positively correlated to SOC, TN, and TP in 0-10 cm and 10-20 cm soil layers. Soil bulk density was negatively correlated to SOC, TN and TP. The alkaline N, available P, available K, and water content were significantly correlated to C/N and C/P in 10-20 cm soil layer. The contents and stoichiometry of soil C, N and P were affected by both ecological restoration measures and soil depth. The shrub-grass intercrop pattern was most beneficial to improve sandy soil environment quality in the study area.

Key words: alpine desertified grassland, northwestern Sichuan, ecological restoration, ecochemical stoichiometry