FRACTAL ANALYSIS OF THE DYNAMICS OF POPULATION PATTERNS DURING VEGETATION SUCCESSION

Abstract

The dynamics and fractal characteristics of population patterns during vegetation succession are rarely explored. Scale, pattern and process of ecological succession are three intertwined concepts in modern ecology. Succession research will inevitably involve scale and pattern analyses. Fractal theory can be employed as an effective tool for synergic analysis of scale, pattern and successional processes. There are few reports on pattern dynamics of Pinus massoniana, a species that declines during succession in southern China. Five forest communities were selected in Heishiding Nature Reserve, Guangdong Province for a case study. Our objectives were to determine (1) whether results obtained by employing fractal analysis are consistent with those from traditional research where space is substituted for time and (2) the pattern dynamics of P. massonianaand the ecological meaning of the change of fractal characteristics in succession. For the traditional space-for-time succession approach, we analyzed importance value (IV) and mean diameter at breast height (DBH) ofP. massoniana, and the selected forest communities were treated as a time series of five successional stages. The box-counting dimension (Dbox) and information dimension (Dinfo) from fractal theory were employed to analyze the pattern dynamics of P. massoniana. Dbox and Dinfo ofP. massonianadecreased during succession, in accordance with number of individuals and IV, and the traditional method of substituting space for time was applicable in this study. This demonstrated deteriorating regeneration conditions and decreasing ability of spatial occupation of P. massoniana with succession—that P. massonianahad a declining population. With its loss of dominance, the community would turn from P. massoniana dominance into a multi-population dominated evergreen broadleaved forest community. The results of fractal analysis were not only consistent with those of the trend analysis of IV and mean DBH, but also yielded more ecological information a bout scale-related spatial pattern of the population, its degree of spatial occupation and its role in community and regeneration conditions. This study indicated that fractal analysis is an effective approach to study dynamic pattern analysis during forest succession, and the results were more reliable than those obtained by employing only IV and meanDBH in a traditional space-for-time approach.