苏南丘陵山区典型次生森林群落的点格局分析

为研究北亚热带丘陵山区次生森林在不同演替序列中群落的空间结构特征,对江苏省南京市溧水林场区域内36块30 m×30 m样地中的木本植物分布进行了详细调查。在利用典范相关分析(CCA)确定不同演替阶段典型群落类型的基础上,运用点格局分析方法对各类型群落中优势树种的空间分布格局进行研究。结果表明:研究区典型森林群落类型为马尾松-麻栎群落、冬青-马尾松群落、麻栎-栓皮栎群落和杉木-油桐群落,土壤条件是影响该地区植物群落组成差异的首要因素。各群落类型中的优势乔木树种在>3 m的空间尺度上通常都表现为均匀分布格局,推断种内竞争可能是形成这种格局特征的重要原因。主要乔木树种之间的空间关联通常表现为中性关系,而对于麻栎-栓皮栎这种功能属性相近的树种,由于受到种间竞争驱动从而表现出显著的负相关。

Point pattern analyses on typical secondary forest communities in the mountainous region of southern Jiangsu Province

To explore spatial structure of secondary forest communities at different succession series in the hilly area of northern subtropical China, we set up 36 sampling plots in the Lishui Foresty Farm, Jiangsu Province, and conducted detailed field investigations on the woody plants in these plots. We distinguished four typical community types using canonical correlation analysis(CCA)across our study plots, and then used point pattern analysis to characterize the spatial distribution patterns of the main tree species for these community types. Our results suggested that in the study area typical forest communities were represented as Pinus massoniana-Quercus acutissima community, Ilex chinensis-P. massoniana community, Q. acutissima-Q. variabilis community and Cunninghamia lanceolata-Vernicia fordii community. Soil conditions appeared to be the primary factor resulting in the difference of community composition. Most dominant tree species in the study communities showed uniform patterns on the scale of >3 m, suggesting that intraspecific competition underlies such pattern formation. Interspecific spatial association often manifested neutral patterns, except for those species such as Q. acutissima and Q. variabilis, which presented significant negative correlations. Interspecific competition due to similar functional traits of these tree species was a likely driving mechanism of such association. Our study could provide a useful reference to effective management of secondary forests in northern subtropical China.