紫金山针阔混交林空间结构特征分析

An Analysis on the Spatial Structure of Coniferous and Broadleaved Mixed Forest in Zijin Mountain

结合林分树种组成、胸径、树高等传统因子,运用混交度、大小比数、角尺度、开敞度4个林分空间结构参数指标分析了紫金山针阔混交林,旨在明晰紫金山针阔混交林的空间结构特征。结果表明,乔木层共包括16个树种,马尾松和栓皮栎在种群密度和断面积上均占有明显优势,是乔木层的建群种和优势种;林分平均混交度达0.70,属强度混交范畴,各树种混交度以冬青最低;马尾松和栓皮栎在空间结构单元中以优势木和亚优势木为主,其他树种优势木较少;林分的平均角尺度为0.59,林木水平分布格局为聚集分布,但聚集程度较低;林分的平均开敞度为0.20,林木生长空间处于严重不足和不足的临界状态;林下缺乏马尾松种群的更新个体,林分最终将演替为带有常绿成分的落叶阔叶混交林。

To investigate the spatial structure of coniferous and broadleaved mixed forest in Zijin Mountain, 4 spatial structure indices （i. e. mingling, angle index, neighborhood comparison and opening degree） together with several traditional indices （e. g. species composition,tree height,diameter at breast height） of the forest were measured and analyzed. The results showed that the forest was composed by 16 tree species. The forest was highly mixed at whole stand level, suggested by an average mingling degree of 0.70. Among all the observed species, Ilex chinensis was the least mixed one. Pinus massoniana and Quercus variabilis composed the majority of dominant and sub-dominant trees in the spatial structural units. The horizontal pattern of the stands displayed a low degree of aggregative distribution,with a uniform angle in- dex of 0.59. The growing space for most trees in the forest was severely insufficient,indicated by an aver- age opening degree of only 0.20. Given that no recruitment of P. massoniana seedlings or saplings were ob- served,we concluded that this coniferous and broadleaved mixed forest was on the track of succession to deciduous broadleaved mixed forest with a few evergreen-tree species.