桂林岩溶石山青冈优势种群空间分布格局及关联分析

Spatial distribution pattern and correlation analysis of Cyclobalanopsis glauca dominant population in karst hills of Guilin

种群空间分布格局是研究种群特征、种间相互作用以及种群与环境关系的重要手段。青冈(Cyclobalanopsis glauca)是岩溶生态系统顶极群落的建种群,为进一步了解其种群空间分布格局特征,该研究根据样地调查规范对面积为60 m×60 m样地中的木本植物进行空间定位且进行每木调查,并运用点格局方法中的g(r)和L12(r)函数对青冈幼苗(DBH<2 cm)、幼树(2 cm≤DBH<10 cm)和成树(10 cm≤DBH)进行空间分布特征和关联性分析。结果表明:(1)青冈种群的径级结构符合倒“J”型分布。(2)幼苗、幼树和成树在较小尺度上表现为聚集分布,而幼树和成树在中、大尺度上基本表现为随机分布。(3)不同径级个体空间关联性主要表现为幼苗与幼树在0~15 m尺度上呈正相关;幼树与成树在0~10 m尺度上呈不相关,而在10~15 m尺度上呈正相关;幼苗与成树在0~2 m尺度上呈不相关,而在2~15 m尺度上呈正相关。因此,青冈种群的分布格局及其关联性随空间尺度和发育阶段而变化,这是由种群自身的生物学特性、种内种间关系以及环境条件共同作用的结果。该研究结果为该区域植物群落形成和维持机制及资源利用研究提供了基础资料。

The spatial distribution pattern of population is an important means to describe population characteristics,interspecific interactions,and the relationship between population and environment.Cyclobalanopsis glauca is a constructive population of climax community in karst ecosystems,in order to further understand the spatial distribution pattern of its populations,according to the sample plot investigation specification,a sample plot of 60 m X 60 m was set up,and the woody plants in the plot were spatially located and investigated for each tree.The C.glauca population wras divided into three different diameter classes in the study,belonging to seedling(DBH<2 cm),sapling(2 cmWDBH<10 cm),adult tree(10 cmWDBH).Using the point pattern analysis method,g(r)and L12(r)functions based on Ripley's K function were used for the analysis of the spatial distribution pattern and correlation analysis of C.glauca population in different diameter classes.The results were as follows:(1)The diameter class structure of C.glauca population was in an inverted“J”type distribution.(2)On the small scale,the stage of seedlings,saplings and adult trees,the spatial distribution pattern tended to cluster distribution,and the saplings,adult trees tended to random distribution on the medium and large scales.(3)The performances of spatial correlation between different diameter classes were different,the seedlings and saplings were positively related on the scale of 0-15 m;saplings and adult trees reflected on the scale of 0-10 m were no correlation,and there was a positive correlation on the scale of 10-15 m;seedling and adult trees reflected on the scale of 0-2 m were no correlation,and there was a positive correlation on the scale of 2-15 m.Therefore,the spatial distribution pattern and correlation of C.glauca population in the karst area of Guilin change with the spatial scale and development stage,which was the result of the combined effects of the population's biological characteristics,intraspecific and interspecific relationships,and environmental conditions.The results of the study can provide basic information for the formation and maintenance mechanism of plant community and resource utilization research of karst hills.