[Cumulative effects of -function in the research of point patterns].

The spatial pattern of plant population is one of primary issues in ecological research. Point pattern analy-sis is considered as an important method to study the spatial pattern of plant population. Ripley's function has been commonly used for point pattern analysis. However, the cumulative effect of Ripley's function may lead to specific spatial pattern charcteristics. To explore how the cumulative effect of Ripley's function affects population pattern, the data of clumped distribution, random distribution and regular distribution of were simulated by R software. All data generated by R software were analyzed by Ripley's function and the non-cumulative pairwise correlation function (). The results showed that for clumped distribution (or regular distribution), the cumulative effect of Ripley's function was manifested in two aspects. On the one hand, the scale of clumped distribution (or regular distribution) was increased due to Ripley's function. On the other hand, Ripley's function could detect the difference of the distribution of cluster (or negative interaction range) in the sampling space, exhibiting different pattern characteristics. For random distribution, Ripley's function had no cumulative effect. In conclusion, the combination of Ripley's function and pairwise correlation function by collecting replicate samples could better reveal the essential characteristics of the pattern in the study of population pattern.