该文研究了广西大青山南亚热带次生林群落经过26年的自然演替其间的种群结构变化规律。通过对主要种群类型、重要值、生态位宽度和分布格局的测定，分析了演替过程中各种群内部的消长与分布变化趋势，研究发现阳生性优势种由高集群分布变为随机分布，其生态位宽度减小，中生及阴生性树种则由随机分布逐渐变为高集群分布，生态位宽度增大。 树种由32种增加到65种，35种中生及阴生树种为后期侵入种，物种多样性比较丰富；通过对现存种群的种间联结与生态位重叠进行分析，揭示了天然次生演替过程中种间关系的相互适应变化规律。原来阳生性的优势树种，如大叶栎(Castannopsis fleuryi)、大叶山楝(Aphanamixis grandifolia)等，与其它种群的生态位重叠值普遍下降，中生性种群生态位重叠值稍有增加，如柃木(Eurya nitida)、血胶树(Eberhardtia aurata)、广西拟肉豆蔻(Knema guangxiensis)等，中生偏阴生性种群生态位重叠值明显增大，其中一些种，如厚叶琼楠(Beilschmiedia percoriacea)、杨桐(Adinandra millettii)、毛黄肉楠(Actinodaphne pilosa) 等，成为群落的建群种和优势种。次生群落种群之间的联结程度加强，一些种从零联结变为高度正联结或负联结，正、负联结性均变得更加紧密，高度正联结的种对占较大比例。种间联结与生态位分析结果基本一致，高度正联结的种群之间生态位重叠值较大，也反映出这些种对生境要求的一致性。次生群落由前期阳生性大叶栎群落演替为中后期中生性厚叶琼楠群落，群落接近较稳定的中生性气候顶极阶段。
Background and Aims Secondary evergreen broad-leaf forest is abundant after large-scale destruction of virgin forests in subtropical areas. Restoration depends largely on natural processes, but these rarely have been studied in Daqingshan, Guangxi. We studied population dynamics of second-growth natural forest over 26 years of succession to explore: 1) patterns of variation in population characteristics and interspecific correlations, 2) the zonal climax vegetation type and 3) effective restoration of degraded secondary forest.
Methods We used methods of population ecology to measure and analyze changes in intra-population structure and spatial distribution, in terms of the population type, importance value, niche breath and distribution pattern. The original investigation on this site took place in 1980 and provided the historic data used for our analysis.
Key Results The heliophytes dominant in early succession changed from highly contagious to random distributions, and their niche breaths decreased accordingly. The mesophytes and shade-adapted tree species, however, had the reverse changes , from random to highly contagious, in concomitance with increasing niche breaths. The number of tree species increased from 32 to 65, of which 35 were late-successional, exhibiting rich species diversity. Niche overlap and interspecific association were analyzed to ascertain the mutual adaptation and evolution of species relationships. Values of niche overlap among the light-adapted populations of Castannopsis fleuryi, Aphanamixis grandifolia, etc. generally dropped, while values for mesophytic populations, such as Eurya nitida, Eberhardtia aurata, Schefflera octophylla, Knema guangxiensis, etc., increased slightly. Values for mesophytes partial to the shaded habitats were enhanced greatly and these species have become dominants, e.g., Beilschmiedia percoriacea, Adinandra millettii, Actinodaphne pilosa, etc. Results of interspecific association analysis were consistent with those of niche overlap analysis, i.e., the species pairs with closely positive associations had large niche overlap, indicating that these species tended to utilize environmental resources similarly.
Conclusions This study shows obvious species changes during the natural restoration process, especially in the quantities and distributions of many dominant species. Results indicate that current communities are increasing in ecological stability as the secondary communities approach the zonal climax through natural succession over 26 years.