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南岭中段森林优势树种及其生态位随海拔梯度变化特征

Characteristics of dominant tree species and their niches in the middle section of the Nanling Mountains with altitudinal gradient

  • 摘要: 本研究在南岭中段海拔400~1 800 m天然林保存良好的区域建立45块生态监测样地,并根据这些样地的海拔分布范围和树种组成归类为4种森林植被类型。通过调查评估关键生态位特征参数指标及生态位资源利用假说的论证,研究不同海拔梯度优势树种的差异及其生态位特征。结果显示:(1)不同海拔梯度优势种存在一定差异性,海拔高差越大,优势种组成差异越明显。(2)高海拔的常绿阔叶矮林区域优势树种对资源需求具有高度的一致性,种间竞争最激烈。(3)优势树种的生态位宽度与其重要值呈弱正相关,与重要值变异系数则呈显著负相关;生态位宽度与生态位的重叠和相似性之间存在一定的联系,但这种联系无明显的规律。(4)重要值和生态位宽度较大且变异系数较小的树种为甜槠(Castanopsis eyrei (Champ.) Tutch)、青冈(Cyclobalanopsis glauca (Thunb.) Oerst)和木荷(Schima superba Gardn. et Champ.),提示这几个树种是南岭中段地区主要的建群树种。(5)中低海拔区域的林分对资源利用方式的划分较符合生态位理论资源利用假说中的随机生态位边界假说;高海拔区域的林分对资源利用方式符合生态位优先占领假说。

     

    Abstract: This study established 45 ecological monitoring plots in well-preserved natural forests within an altitudinal range of 400–1 800 m in the middle section of the Nanling Mountains. These plots were classified into four forest vegetation types based on elevation range and species composition. This study assessed the differences in dominant tree species and their niche characteristics along various altitudinal gradients by surveying key ecological niche parameters and evaluating the niche resource utilization hypothesis. Results indicated that: (1) Dominant species varied at different altitudes, with more pronounced differences in species composition observed at higher altitudinal differences; (2) In the evergreen broad-leaved dwarf forest at higher altitudes, dominant species exhibited a high degree of uniformity in resource requirements, accompanied by intense interspecific competition; (3) A weak positive correlation was found between the niche width of dominant species and their importance value, while a significant negative correlation was observed with the coefficient of variation of importance value. Although niche width was related to niche overlap and similarity, no clear pattern was established; (4) Species with higher importance values, larger niche widths, and smaller coefficients of variation included Castanopsis eyrei (Champ.) Tutch, Cyclobalanopsis glauca (Thunb.) Oerst, and Schima superba Gardn. et Champ., suggesting that these species are the primary constructive species in the middle section of the Nanling Mountains. These findings provide theoretical support for the sustainable management of forest ecosystems and the conservation of plant diversity in the middle section of the Nanling Mountains and beyond; (5) The division of resource utilization in forest stands at middle and low altitudes aligned more closely with the random niche boundary hypothesis in the resource utilization hypothesis of niche theory; in high-altitude areas, the resource utilization mode of forest stands conformed to the niche priority occupation hypothesis.

     

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