广西木论保护区喀斯特常绿落叶阔叶混交林优势种空间格局及其相关性

Spatial patterns of and specific correlations between dominant tree species in a karst evergreen and deciduous broadleaved mixed forest in Mulun Karst National Nature Reserve

基于广西木论国家级自然保护区喀斯特常绿落叶阔叶混交林1hm2样地调查数据,采用点格局方法分析了混交林4个优势种群空间格局,及种内和种间的相关关系.结果表明:木论常绿落叶阔叶混交林乔木层Ⅰ亚层以小栾树为主,Ⅱ亚层和Ⅲ亚层均以东女贞、铁榄和广西密花树为主;4个优势种群不同林层的空间分布格局在<10m尺度上呈显著的聚集分布,>25m尺度呈随机分布,有些尺度呈均匀分布,10～25m尺度内则为聚集分布向随机分布过渡,且不同树种聚集分布向随机分布转化的临界尺度不同.Ⅰ亚层小栾树与Ⅱ亚层4个优势种的相关性较弱;Ⅲ亚层各优势种与Ⅱ亚层4个优势种中,小栾树与4个优势种相关关系波动较大,东女贞<50m尺度内呈显著正相关,铁榄与4个优势种没有明显的相关性,广西密花树在<20m尺度没有相关性,而在20～50m尺度上呈显著负相关.

In order to understand the biological characteristics and specific correlations of dominant tree species in a karst characteristic evergreen and deciduous broad-leaved mixed forest in Mulun National Nature Reserve of Guangxi,a point pattern analysis was made on the spatial distribution patterns and inter-and intraspecific correlations of four dominant species in a one-hectare plot.Among the four species,Boniodendron minius dominated in tree sublayer I,while Ligustrum japonicum,Sinosideroxylon wightianum,and Rapanea kwangsiensis dominated in tree sublayers II and III.All the four species had a clumped distribution at scale 10 m,a transition from clumped to random distribution at scale 10-25 m,and a random or regular distribution at scale 25 m.The critical scale from clumped to random distribution varied with species.No significant correlations were observed between the B.minius in sublayer Ⅰ and the dominant species in sublayer Ⅱ.The correlations of B.minius with the dominant species in sublayers Ⅱ and Ⅲ showed greater fluctuation,with significant positive correlation for L.japonicum at scale 50 m,no significant correlation for S.wightianum,and no significant correlation for R.kwangsiensis at scale 20 m but significant negative correlation at scale 20-50 m.