Abstract:Dynamics of plant biodiversity and structure were studied at three different stages of Mongolian Oak-Korean pine forest regeneration. Forest regeneration was good in the early period with Korean pine and broad-leaved tree species having similar numbers of individuals regenerating. Later, the number of abundance of Korean pine regeneration comes to exceed that of other tree species. With the development of forest, firstly Mongolian Oak and other shade-intolerant tree species initially dominate stands, these are replaced by Korean pine and broad-leaved tree species in a mixed stand, while Korean pine dominates older stands. The modeled dynamics of shrubs and herbs were more complex. Analysis of stem diameter distributions showed that there were more large trees of broad-leaved tree species and fewer small trees of conifer species at early stage, but these conditions are reversed at a later stage. Diameter distributions of the different forest stages were fitted with theoretical models. The results showed that Weibull distribution had the best fit in these Mongolian Oak-Korean pine forest.