The dynamics characteristics of population patterns in the vegetation succession are rarely explored.Scale,pattern and process of ecological succession are three intertwined concepts in modern ecology.Succession research will inevitably involve scale and pattern analyses.Species spatial patterns and interspecific associations at any scale can be analyzed based on point pattern analysis with spatial mapped points of individuals’ distribution.Therefore,it is suitable to discuss the relationships between species pattern in the vegetation succession process which have attracted much attention from ecologists.The aim of the present work is to study the spatial pattern formation and relative importance of intra and interspecific competition in dominant tree species of Betula platyphylla and Larix principis-rupprechtii in the vegetation succession process in Taiyue Mountain.The selected forest communities were treated as a time series of successional stages for the traditional space-for-time succession approach by applying the point pattern analysis.In the present research,ecological succession of B.platyphylla and L.principis-rupprechtii in Taiyue Mountain were dynamic characteristics and interspecific relationship.The series reflected the process from B.platyphylla as the monodominant community to B.platyphylla and L.principis-rupprechtii as the co-dominant communities and then to L.principis-rupprechtii as the monodominant community;Point pattern analysis and Monte-Carlo simulation test were used to analyze the spatial pattern of the two dominant species and their interaction relationship.The following conclusions were drawn.(1)The population structure of Taiyue B.platyphylla was spindle type,presenting a de-clining trend.By L.principis-rupprechtii age class structure is gradually replaced “pyramid” the growth of the population.(2)During the process from B.platyphylla to L.principis-rupprechtii as the monodominant community reflected,the spatial pattern of B.platyphylla changed from clumped to nearly random distribution,which was mainly caused by the colonization and expansion of L.principis-rupprechtii and the resulted interspecific competition.Besides,the spatial scale of L.principis-rupprechtii community gradually increased,with the species colonization and intraspecific competition as the major cause,which was driven by the intraspecific competition caused by the self-thinning effects and the colonization and expansion of L.principis-rupprechtii and the resulted interspecific competition.(3)In terms of the interspecific competition between the two species (B.platyphylla and L.principis-rupprechtii),no obvious relationship was found when B.platyphylla acted as the monodominant community,significant negative relationship was identified at the co-dominant stage,and no obvious relationship when L.principis-rupprechtii became the dominant species.The change of relationship between the two species was mainly driven by the intraspecific and interspecific competition for residual resources.