关键词: 南亚热带, 次生常绿阔叶林, 演替, 种群动态, 广西大青山

Abstract:

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.

Key words: Subtropical area, Secondary evergreen broad-leaf forest, Succession, Population dynamics