Abstract:
By analyzing the characteristics of plant reproductive banks in alpine meadows at the top of mountains, a basis was provided for evaluating the ecological functions and ecological security of mountain forest systems in the mountains on the northern edge of the Sichuan Basin. 6 altitude gradients (
2750±50 m,
2850±50 m,
2950±50 m,
3050±50 m,
3150±50 m, >
3200 m) were set up on 3 main mountain peaks in Tangjiahe Nature Reserve. By measuring plant indicators such as plant species and quantity, community composition and characteristics in the seed bank and bud bank, to determined the species and density contribution rates of 4 functional groups such as grasses, sedges, legumes, and forbs. Variations in species composition, density, and contribution rates of functional groups across altitudes were analyzed to examine the influence of altitude on the characteristics of the plant reproductive banks and on the contribution rates of functional groups. The results showed that: 1) The reproductive bank characteristics were affected by altitude as following order: bud bank density> seed bank species number > bud bank species number > seed bank density. With increasing altitude, the species richness of both the seed and bud banks, the number of shared species, and the similarity coefficient decreased significantly. In contrast, the overall density of the reproductive bank increased significantly (
P<0.05). 2) Altitude had a significant effect on species richness, density, and contribution rates of functional groups in both the seed bank and bud bank (
P<0.05). The order of influence across functional groups was consistent: forbs > grasses > sedges > legumes. Forbs were identified as the primary functional group determining the characteristics of the reproductive bank. 3) As altitude increased, the species richness, density, and contribution rate of forbs in both the seed bank and bud bank showed significant declines. In contrast, grasses exhibited higher species richness, density, and contribution rates in reproductive bank at
2950 m compared to other altitudes. Sedges demonstrated significantly greater species richness, density, and contribution rates in the seed and bud banks at altitude above
3050 m relative to other functional groups. Legumes contributed notably to the reproductive pool only at altitude exceeding
3050 m. 4) At altitudes above
2950 m, the contribution of the seed bank to the reproductive bank declined, and the contribution of forbs to the reproductive bank also decreased. In contrast, the bud bank of sedges, which relies on clonal reproduction, became the dominant component of the reproductive bank in this range. In summary, altitude significantly affected the composition, structure, and capacity of the reproductive banks in alpine meadows in this region. Altitude also significantly affected the species richness, density, and contribution rates of functional groups in both the seed bank and bud bank. Across all six altitude gradients, the reproductive banks exhibited adaptations to their respective habitats, thereby providing a rich seed source foundation for the natural regeneration of grassland ecosystems.