紫金山针阔混交林主要树种空间分布格局及种间关联性

【目的】明晰紫金山针阔混交林主要树种的空间格局及种间关系。【方法】根据1 hm²典型林分样地调查结果,计算了每个树种重要值,分析了种群胸径分布和主要树种在100 m²尺度下种群的空间聚集强度指标、种间联结系数与显著度。【结果】在紫金山针阔混交林区,重要值前7位的马尾松、栓皮栎、朴树、紫薇、短柄枹、椤木石楠、黄连木是主要树种; 除马尾松外,其余主要树种的幼苗、幼树数量均多于大树数量,属于进展种群。各主要树种种群的空间格局均属于集群分布,聚集强度大小为椤木石楠>紫薇>短柄枹>栓皮栎>朴树>马尾松>黄连木; 建群种马尾松空间格局随进展演替趋于随机分布。主要树种种群之间的总体关联性呈不显著正关联。7个主要树种构成的21个种对关联性中,13个呈不显著正联结,1个呈极显著正联结,以及7个呈不显著负联结,其中正联结多集中在地带性乡土树种之间。【结论】紫金山针阔混交林正向含有常绿成分的落叶阔叶林过渡。

Spatial distribution pattern and interspecific association of dominant tree species in a broad-leaved mixed forest on Zijin Mountain

【Objective】In this study, we aimed to evaluate the spatial distribution patterns and interspecific associations of dominant tree species in a coniferous and broad-leaved mixed forest on the Zijin Mountain.【Method】On the basis of the data collected from a 1 hm² plot, important values(IV)of the tree species were calculated and diameter at breast height(DBH)distributions were analyzed. The intensity of spatial aggregation, coefficient of interspecific association and significance of species dominance at the scale of 100 m² were also analyzed.【Result】In the broad-leaved forest on Zijin Mountain, Pinus massoniana, Quercus variabilis, Celtis sinensis, Lagerstroemia indica, Quercus glandulifera, Photinia davidsoniae and Pistacia chinensis were defined as the dominant tree species with top seven IVs. Apart from Pinus massoniana, the number of seedlings and saplings were more than bigger tree in the other dominant tree populations belong to growing type. All dominant tree populations showed a contagious spatial distribution, and the aggregation ranking was as follow: Photinia davidsoniae>L. indica>Q. glandulifera>Q. variabilis > C. sinensis>Pinus massoniana>Pistacia chinensis. The spatial distribution of the Pinus massoniana population gradually shifted to a random pattern along the successional process. In general, associations of the dominant tree populations tended to be positively correlated, but statistically non-significant. Among 21 species pairs of the seven tree species, 13 pairs were non-significantly positively associa-ted, one pair was significantly positively associated, and seven pairs were non-significantly negatively associated. Besides, the positive associations were mainly concentrated in the zonal native tree species.【Conclusion】Currently, the coniferous and broad-leaved mixed forest on the Zijin Mountain is gradually transiting to a deciduous broad-leaved forest with some evergreen components.