Abstract:

Studying the distribution patterns of plant diversity along altitudinal gradients is crucial for the successful restoration of forest vegetation and the conservation of species. To reveal the vertical distribution characteristics of plant diversity in mountainous areas, eight elevations (800, 900, 1000, 1100, 1200, 1300, 1400, and 1500 m) in Nanling Nature Reserve were studied. The distribution pattern of plant diversity at different elevations was analyzed, and the logarithmic Cauchy model was used to fit plant abundance at different elevations. The results showed that 1) there were 290 species belonging to 148 genera and 81 families in eight altitudinal gradient plots in Nanling. 2) The species diversity of Nanling showed a “unimodal” trend along the altitude gradient, and the species diversity index (species richness index 157, Shannon-Wiener index 4.142, Pielou’s evenness index 0.459) was highest at middle altitudes (1000-1300 m). The high-altitude areas (1300-1500 m) had the lowest species richness index (69), Shannon-Wiener index (2.317), and Pielou evenness index (0.197). 3) The phylogenetic diversity of the tree layer (−2.918 to 0.762) differed from species diversity, and phylogenetic diversity showed a discrete structure in general. The environmental filtering effect played an important role in the construction of the Nanling forest community, and the competitive exclusion effect gradually appeared in the high-altitude forests. 4) Habitat restriction and interspecific competition in the middle- and high-altitude communities may weaken the formation potential of dominant species in the tree layer but increase the coexistence probability of rare species in the community. In terms of species protection, humans severely disturb low altitudes, and it is recommended that an ecological red line be set at low altitudes (800-1000 m). High-altitude areas (1300-1500 m) of forest habitats are relatively poor, but are important habitats for many rare and endangered plants. Good growth conditions, such as reduced intensity of interspecific competition and an improved microclimate, should be created for these species. The results of this study deepen our understanding of the changes in plant community biodiversity in Nanling evergreen broad-leaved forests and contribute to the formulation of biodiversity conservation strategies in this region.

Key words: Nanling, elevation gradient, species diversity, phylogenetic diversity, species abundance distribution

摘要：

研究植物多样性沿海拔梯度分布格局对森林植被恢复和物种保护具有重要作用。为探讨山地地区植物多样性垂直分布特点，以南岭自然保护区8个海拔梯度（800、900、1000、1100、1200、1300、1400和1500 m）为研究对象，从群落水平和系统发育水平两个方面，分析不同海拔梯度植物多样性分布格局，并结合对数柯西模型进行不同海拔梯度植物多度拟合。结果表明：1）南岭8个海拔梯度样地内共有物种290种，隶属81科148属；2）南岭物种多样性沿海拔梯度呈“单峰”趋势，中海拔（1000—1300 m）物种多样性指数（物种丰富度指数157、Shannon-Wiener指数为4.142、Pielou’s evenness指数为0.459）最高，高海拔（1300—1500 m）最低（物种丰富度指数69、Shannon-Wiener指数为2.317、Pielou’s evenness指数为0.197）；3）乔木层系统发育多样性（−2.918—0.762）变化趋势异于物种多样性，系统发育总体上呈离散结构，环境过滤效应在南岭森林群落构建中起重要作用，竞争排斥效应在高海拔森林中逐渐显现；4）中高海拔群落中生境限制和种间竞争可能削弱乔木层优势种的形成潜力，但提高罕见种在群落中的共存概率就物种保护而言，低海拔（800—1000 m）人为干扰严重，建议低海拔设置生态红线，高海拔（1300—1500 m）森林生境则相对恶劣，却为众多珍稀濒危植物的重要栖息地，建议为这些物种创造良好的生长条件，如降低种间竞争强度、改善小气候等。研究结果将加深对南岭常绿阔叶林植物群落生物多样性变化格局的认识，有助于该区域多样性保护策略的制定。

关键词: 南岭, 海拔梯度, 物种多样性, 系统发育多样性, 物种多度分布