Objective The soil seed bank serves as a reservoir of propagules essential for vegetation community regeneration and succession. This study investigates the distribution patterns of soil seed banks in subalpine forest ecosystems and their relationship with aboveground vegetation to evaluate the ecosystem's capacity for natural vegetation recovery. The findings provide a foundation for community restoration and ecological rehabilitation practices.

Method The study focused on the subalpine forest region in Bayi District, Linzhi City, Tibet, spanning an altitude range of 2 300 m to 3 300 m. A systematic sampling approach was employed to conduct aboveground vegetation surveys and soil sampling. The germination method was utilized to determine the species composition, life-form composition, and density distribution characteristics of the soil seed bank.

Result (1) A total of 30 species (representing 15 families and 27 genera) germinated from the soil seed bank. These species were predominantly annual or perennial herbaceous plants, with a relatively homogeneous species composition compared to the aboveground vegetation community. (2) The species richness of both the soil seed bank and aboveground vegetation exhibited an "increase followed by a decrease" trend with increasing elevation. Additionally, the proportion of perennial herbs increased, reflecting their strong adaptability to high-elevation environments. (3) The Margalef, Shannon, and Simpson indices initially increased and then decreased with rising elevation. The Sørensen similarity indices between the soil seed bank and aboveground vegetation at different elevations were low (0.240–0.375) and tended to decline with increasing elevation. (4) Aboveground vegetation density was positively correlated with soil seed bank density (r = 0.721, P < 0.01). Soil seed density displayed an “increase followed by a decrease” trend with elevation, ranging from (47.22 ± 2.78) seeds/m² to (141.67 ± 13.89) seeds/m². The vertical distribution of soil seed density showed a decreasing trend, with a clear pattern of enrichment in the surface layer (0–10 cm).

Conclusion Significant differences exist between the soil seed bank and aboveground vegetation communities in terms of species richness and life-form composition in the subalpine forest region. Furthermore, the low density of the soil seed bank suggests that natural recovery of the original vegetation communities using the soil seed bank alone is challenging. Therefore, establishing an artificial seed bank of native species is recommended to enhance ecological restoration efforts. This study elucidates the seed bank's response to altitudinal gradients and its coupling relationship with aboveground vegetation in the subalpine forest area, providing theoretical support for assessing the soil seed bank's potential for vegetation restoration and formulating ecological restoration strategies in this region.