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四川盆地北缘山地高寒草甸植物繁殖库功能群组成及贡献率沿海拔梯度变化

Altitudinal varies in functional group composition and contribution of the reproductive bank in an alpine meadow, northern Sichuan Basin

  • 摘要: 研究高寒草甸植物繁殖库特征,为四川盆地北缘山地森林系统生态功能和生态安全评估提供依据。在唐家河自然保护区3座山峰6个海拔梯度(2750±50 m,2850±50 m,2950±50 m,3050±50 m,3150±50 m,>3200 m)的高寒草甸上,各设置6个5×5 m2样地,按禾草类、莎草类、豆科类和杂类草划分功能群,调查种子库和芽库的植物种类与数量,分析海拔间功能群种类、密度及贡献率差异,研究海拔对植物繁殖库特征及功能群贡献率影响。结果表明:1)海拔对植物繁殖库特征影响大小为芽库密度>种子库物种数>芽库物种数>种子库密度,随海拔升高,种子库和芽库物种数、共有物种数和相似性系数显著下降,繁殖库总密度显著增加(P<0.05)。2)海拔显著影响种子库和芽库功能群物种数和密度及贡献率(P<0.05),受影响大小均为杂类草>禾草类>莎草类>豆科类,杂类草是决定繁殖库特征的第一功能群。3)随着海拔升高,杂类草的种子库和芽库物种数、密度及贡献率均显著下降,禾草类在海拔2950 m处种子库和芽库的物种数、密度及贡献率均高于其他海拔,莎草类在海拔>3050 m区域种子库和芽库的物种数、密度及贡献率显著高于其他功能群。豆科类仅在海拔>3050 m时对繁殖库表现出较高的贡献率。4)海拔>2950 m种子库对繁殖库、杂类草对繁殖库贡献率下降,莎草类克隆繁殖为基础的芽库成为繁殖库的主体。综上,海拔显著影响四川盆地北缘山地高寒草甸繁殖库组成、结构和库容,海拔显著影响种子库和芽库的功能群物种数、密度及贡献率,6个海拔均形成匹配生境的繁殖库,为草地自然更新提供了丰富的种源基础。

     

    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.

     

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