Abstract: The stoichiometric characteristics of carbon (C), nitrogen (N), and phosphorus (P) in plant and soil are important indicators for ecological functions of vegetation under different restoration types. We analyzed C:N:P stoichiometric characteristics and the driving factors in plant components (leaves, litter, roots) and 0-100 cm soil layers across three typical restored vegetation types in the northern forest-grassland ecotone, including artificial arbor forest, artificial shrub forest, and natural grassland. The results showed that the average C contents in plant leaves, litter, and roots ranged from 371.60 to 402.07, 378.59 to 413.66, and 364.05 to 406.83 g·kg^-1; the average N contents ranged from 13.23 to 27.81, 9.52 to 12.06, and 5.20 to 13.31 g·kg^-1; and the average P contents ranged from 0.85 to 1.02, 0.28 to 0.82, and 0.16 to 0.89 g·kg^-1, respectively. Leaves had the highest nutrient concentrations. Artificial arbor forest tended to have high C contents in leaves and roots. Artificial shrub forest was characterized by high N contents in plant components. Natural grassland featured high P contents in litter and roots. There was no difference in C content among components in arbor forest, but C content followed the order of litter > leaves > roots in shrub forest and grassland. N and P contents were higher in leaves than other tissue in artificial vegetation, but they were evenly distributed across tissues in natural grassland. The average contents of soil C, N, and P in the surface layer (0-20 cm) of the three vegetation types ranged from 7.45 to 10.76, 0.38 to 0.54, and 0.31 to 0.46 g·kg^-1; the average C/N, C/P, and N/P ranged from 19.9 to 24.2, 24.1 to 27.1, and 1.2 to 1.5, respectively. Soil N content and N/P were significantly lower than the average level of Chinese soils, indicating N limitation in this area. In all soil layers, soil C content in natural grassland was significantly higher than that in artificial vegetation, soil P content in artificial shrub forest was the lowest, and no significant differences in soil N content, C/N, C/P, and N/P among vegetation types. There were significant positive correlations between N and P in leaves and roots, and among soil C, N, and P contents in natural grassland, showing strong element synergy. Redundancy analysis demonstrated that soil C:N:P stoichiometry were mainly regulated by soil pH, NO₃^--N, and nutrient contents in plants, with specific responses in different vegetation types. In conclusion, the coordinated and open nutrient cycling of natural grassland is conducive to soil nutrient conservation and long-term ecosystem stability.

Key words: vegetation restoration, leaf, litter, root, soil, ecological stoichiometry