Regeneration behaviors of tree species under different thinning intensity were investigated in secondary forests of Pine mass-dieback, in Himeji, Hyogo Prefecture, Japan. Regenerated forests occurred by sprout formation and by growth of saplings, and the proportion of sprouted formation to total regeneration (PSRG) was different under thinning intensity. Following the management, regeneration occurred more often by sprout formation than by growth of saplings in clear-cut areas, while regeneration occurred more often by growth of saplings than by sprout formation in thinning areas. Four groups of tree species could be classified based upon the tree density of individuals (H >= 1.3m) and PSRG. Type A regenerated many individuals independently of thinning intensity and had PSRGs of more than 50%. Type B regenerated many individuals independently of thinning intensity and had PSRGs of less than 50%. Type C regenerated many individuals in clear-cut areas had PSRGs of more than 50%. Type D regenerated many individuals in only clear-cut areas and had PSRGs of less than 50%. Tree species belonging to Type A were Ilex pedunculosa, Lyonia ovalifolia and Eurya japonica etc., and their species regenerated many individuals. These results suggest that the selective and high frequency removal of Type A species provide richness for other tree species.
