Floristic changes and regeneration patterns for a 12-year period during the 3rd and 4th decades following selection logging in a subtropical rainforest

Changes in regeneration patterns in a subtropical rainforest in north-east New South Wales (Australia) are presented for a 12-year period during the 3rd and 4th decades following repeated single-tree selection logging. Changes were investigated using multivariate and univariate approaches. There were no significant differences in floristic assemblages within and between censuses. However, two contrasting trends of changes in plant groups were detected. In trees with a diameter at breast height (d.b.h.; that is, 1.3 m above the ground level) ≥ 10 cm, both the density and species richness increased in the shade-tolerant group, while density increased and species richness decreased in the shade-intolerant group. Among smaller sized regenerating species including trees (1.3 m in height < 10 cm d.b.h.), a general decrease in species richness was observed along with significant changes in stem densities where the number of stems in the shade-tolerant species increased while that of both shade-intolerant and vine species decreased. Excluding the vines and understorey species from the broader regenerating species, revealed a decrease in species richness in juvenile canopy tree, and a significant change in densities with the number of stems in the shade-tolerant increasing while that of shade-intolerant trees decreased. A comparison between the canopy trees ≥ 10 cm d.b.h. and the juvenile canopy trees group showed that these groups were tending towards similar floristic assemblages. These results suggest gradual replacement of shade-intolerant by shade-tolerant species as stands tend toward later stages of regeneration. This study shows that the inclusion of regenerating species in long-term studies is both complementary to the larger plant component and more revealing of both trends and changes.