桂林岩溶石山檵木种群空间格局及其关联性

种群的空间分布格局及其关联性反映了种群演替方式和对环境因子的适应策略,对植被的恢复与重建、生物多样性保护等具有重要的意义和价值.为了解桂林岩溶石山檵木种群的空间分布格局及其关联性,在对其进行群落调查的基础上,采用点格局方法,以Ripley K函数为基础,运用其衍生的成对相关函数和Ripley L函数对檵木种群的空间分布格局以及不同径级之间关联性进行分析.结果表明:檵木种群的径级结构呈倒“J”型分布,小径级个体占较大比例,种群自然更新状况良好,属增长型种群;檵木种群3个径级的个体在小尺度上呈聚集分布,但随着空间尺度的增大,聚集强度逐渐减弱,趋向随机分布;檵木种群3个不同径级的个体间在小尺度下均呈现无关联,随着尺度增大,不同径级个体的空间关联性呈现正关联或负关联;檵木种群个体间径级差异越大,它们的空间关联性越弱,甚至可能逐渐转变为负关联.本研究结果有助于了解桂林岩溶石山檵木种群在生长发育过程中的生态策略和物种共存的尺度依赖性特征及其形成机制,从而为岩溶石山森林植被的恢复与重建、保护和经营管理提供参考.

Spatial distribution patterns and association of Loropetalum chinense population in karst hills of Guilin,Southwest China

The spatial distribution and association of populations can reflect succession patterns and its adaptation strategies to the change of environmental factors, with important significance for vegetation restoration, reconstruction, and biodiversity conservation. We used the point-pattern analytical method to examine the spatial distribution and its association of the Loropetalum chinense population in karst hills of Guilin, China, based on field surveys. On the basis of Ripley K function, we used the pair-correlation function statistic derived to explore difference in the distribution patterns.We used Ripley L function to examine the spatial associations among the three diameter classes. The results showed that the diameter class structure of the population exhibited an irregular inverted “J” type, with the small diameter class occupying a large proportion, indicating an increased population structure with good regeneration capability. The individuals of the three diameter classes had a clumped distribution at the small scale. With the increases of spatial scales, the aggregation intensity gradually weakened and tended to be randomly distributed. There was an independent spatial association between individuals among the three diameter classes at small scale. As the scale increased, the spatial association between individuals with different diameter classes became positive or negative association. The greater the difference in diameter class of L. chinense population, the weaker their spatial correlation was, which might gradually turn into negative association. Our findings contributed to a clearer understanding of the ecological strategies and scale-dependent cha-racteristics of species coexistence and underlying mechanisms during the growth and development of L. chinense population in karst hills of Guilin, providing reference for the restoration, reconstruction, protection and management of forest in karst hills.