Thirty-year stand dynamics of an old evergreen coppice forest in Southern Kyushu, Southwestern Japan

We investigated forest development processes for a period of 30 years (during 87–116-year-old) in an evergreen coppice stand in southern Japan that was highly dominated by Castanopsis sieboldii. Stand age changing developmental stages were verified and compared with the results of a previous case study of evergreen coppices mainly dominated by C. cuspidata, C. sieboldii and Quercus salicina in the same region. A survey plot was established in 1985, and tree height and diameter at breast height of all living stems were recorded. Stems of single-stem individuals and multi-stem individuals were distinguished based on observations of stem bases for each of the overstory and understory. Changes in stem density and species diversity were then evaluated. In the overstory, stem density declined between 92- and 116-year-old. On the other hand, stem density in the understory exhibited a distinct increase during the study period; however, it was primarily single-stem and multi-stem evergreen shrubs, such as Aucuba japonica, and multi-stem evergreen trees, such as C. sieboldii that contributed to this increase. The species diversity index (H’) also indicated the same trends. Therefore, it was concluded that the stand examined in the present study exhibited characteristics of the “understory re-initiation” stage after 92-year-old, and that stand development was delayed compared to development of stands examined in a previous study. These results indicated that the progress of stand development may differ depending on dominant species or forest environment even within evergreen coppices in the same region.