Abstract: 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.

Key words: Aphis gossypii, host plant, life table, population parameter.