Chin J Plant Ecol ›› 2007, Vol. 31 ›› Issue (4): 568-575.DOI: 10.17521/cjpe.2007.0073

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XIANG Wu-Sheng, LI Xian-Kun*, SU Zong-Ming, OU Zu-Lan, LU Shu-Hua   

  1. Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin, Guangxi 541006, China
  • Received:2006-07-07 Accepted:2007-01-05 Online:2007-07-07 Published:2007-07-30
  • Contact: LI Xian-Kun


Aims Taxus chinensis var. mairei is the material from which taxol, an effective low-toxicity cancer-resistance medicine, is distilled. This species reproduces asexually, especially through sprouting from stems, which enables Taxus to expand its spatial occupation and maintain its population. Therefore, study on clonal properties of Taxus populations may provide a scientific basis for protecting and regenerating populations. This study addresses the following questions: 1) what are the fractal properties of population distribution patterns, 2) are clonal architecture and fractal properties correlated and 3) are fractal properties and aggregation correlated?
Methods Based on a survey of Taxus, we established four 40 m × 15 m plots in its central distribution area in Yuanbaoshan Nature Reserve. For each plot, we determined the spatial coordinates of each Taxus individual. For Taxus > 3 m tall, we measured height, crown size, height to branches and diameter at breast height; for shorter Taxus seedlings and saplings, only height was measured. We also estimated or measured cover and height of shrubs and herbs. Fractal properties of population patterns were analyzed by using the box-counting dimension and the information dimension.
Important findings The box-counting dimension ranged from 0.993 1 to 1.353 1, which was far from the theoretical value 2, indicating low degree of spatial occupation. Significant correlation between the clonal architecture index and the box-counting dimension indicates that degree of spatial occupation was closely related to clonal architecture, i.e., populations tending to have phalanx clonal architecture had a stronger degree of spatial occupation than those tending to have guerrilla clonal architecture. The information dimension varied from 1.350 8 to 1.652 1 with community type. The Pearson correlation between information dimension and pattern index is significant, suggesting that differences of information dimension could reflect variation of the aggregation intensity. Information dimension was closely related to number and spatial distribution patterns of ramets.

Key words: count-box dimension, information dimension, clonal architecture, aggregate intensity, Yuanbaoshan Mountain, clonal populations