Dynamics of multi-stem clump structure of canopy trees affects the change in stand structure of secondary lucidophyllous forests

Abstract

We investigated stand and multi-stem clump structure of nine stands of secondary lucidophyllous (warm-temperate natural evergreen) forests with different ages to clarify the effects of the dynamics of multi-stem clump structure on the change in stand structure along the secondary succession after felling. As a result, three major stages were detected in the developmental process of the secondary forest as follows. 1) Up to 18 years after felling, secondary forests consisted of both multi-stem canopy trees of sprout-origin and understory individuals of seedling origin of lucidophyllous species, whereas pioneer species which might have dominated the canopy at the stand initiation stage disappeared due to the suppression by evergreen multi-stem individuals of sprout origin. 2) The proportion of multi-stem individual and average number of stems of canopy trees decreased during 23-46 years after felling. This change indicated stem exclusion within the clump of multi-stem individuals. We suggest that the severe competition between stems within the clumps provided a dark environment on the forest floor, resulting in exclusion of the seedlings of lucidophyllous species. 3) Since 60 years after felling, the number of canopy trees of sprout origin decreased, indicating the change from death of stem level to individual level. This probably resulted in gap formation and heterogeneous canopy structure, which improved the light environment on the forest floor and promoted the reinitiation of understory individuals.