Growth of a shade-intolerant tree species, Phellodendron amurense, as a component of a mixed-species coppice forest of central Japan

A generally accepted trend in secondary succession – the decline in dominance of shade-intolerant species was examined. We dealt with a shade-intolerant species, Phellodendron amurense Rupr. in a 38 ha mixed-species coppice forest. There were 45 stems of P. amurense with dbh (diameter at breast height) ≥10 cm in the forest. P. amurense had smaller means of stem sizes (dbh, height, and crown ratio) and basal area increments than those of their neighbors. Analysis on choosing cores indicated that most of P. amurense had already been under a suppressed condition at 20 years after their establishment, and obviously showed decline in growth during the following stages. Although they could grow faster without any suppression, their sensitivity to shading effects was greater than other more tolerant species. It seemed that suppression by species with deep crowns was particularly prominent. Such extreme responses to suppression seemed to cause decrease in growth rate after the onset of suppression in the actual forest. We conclude that two factors: the relative growth rates in the initial stage, and the species composition in the following stage are considered to be definitive in the declining process of P. amurense.