北京松山自然保护区天然油松林不同龄级立木的空间点格局

采用点格局分析法对油松不同龄级个体的分布格局及其相互关系进行了研究.结果表明，油松不同龄级密度差异较大，高龄级密度较大（龄级Ⅰ密度为15 株·hm^-2，龄级Ⅲ密度为924 株·hm^-2）.油松各龄级的分布格局以及龄级间的空间关联与尺度（40 m内）密切相关，在小尺度上油松各龄级趋于聚集分布，龄级间有较强的相关关联；当空间尺度大于临界值（30 m或40 m）时，油松各龄级趋于随机分布，龄级间的空间关联性减弱.

Spatial patterns of different age-class individuals in Pinus tabulaeformis forest in Songshan Nature Reserve of Beijing, China

By the method of point pattern analysis, this paper studied the spatial patterns of different age-class individuals in the Pinus tabulaeformis forest in Songshan Nature Reserve of Beijing, and the spatial association between the individuals. The results showed that there existed greater differences in the densities of different age-class P. tabulaeformis individuals, e.g., age-class I had the density of 15 plants per hectare, while age-class III had the density of 924 plants per hectare. The spatial patterns of different age-class individuals and the spatial association between the individuals had a close relationship with the spatial scale. In the scale of < 40 m, the individuals of all age-classes tended to clump, and there was a stronger spatial association between the individuals of different age-classes. When the scale was larger than 30 m or 40 m, the individuals of all age-classes would disperse randomly, and their spatial association would be weakened greatly.