Abstract: Based on investigation on the communities,the woody plant species at three topography sites in Maolan National Nature Reserve were selected as the object of research.Through the calculation of important values,forty-two dominant species were selected in each communities.Overall association,interspecific association,percentage co-occurrence (PC) and association coefficient(AC) were used to analyze the interspecific association of these dominant species.The results showed that:(1) overall association of community in research area was insignificant positive association and it was in accord with interspecific association.Populations were easy to arise independently.Community was in a relatively stable stage.(2) the interspecific associations of communities at different topography sites were different.In funnel and valley communities,overall association was insignificant positive association,and more species-pairs had positive correlation.In hillside community,overall association was insignificant negative association,and more species-pairs had negative correlation or no correlation.(3)There was higher association among the species-pairs in the funnel and valley communities,and community structure was relatively stable.There was lower association among the species-pairs in the hillside community,and community structure was relatively unstable.Through the interspecific associations of communities,a concluson can be drawn that the loose interspecific relationship may be one of the coexistence mechanisms of karst forest species.There were different forms of the coexistence mechanism in the communities at different topography sites.

Key words: Maolan, karst forest, dominant species, interspecific association, species coexistence