Abstract
Within the framework of a series of secondary succession of a subtropical evergreen broad-leaved forest, the present study was undertaken to clarify stand structure and species diversity of 18-year-old post clearcut-burn regeneration on Iriomote Island, Okinawa. Within a 0.87 ha clearcut study area, four 10 m×10 m plots were installed in the centre of each section, two burned after the clearcut while two left non-burned. After 18 years of sprouting recovery, the woody stems ≥1.0 m in height were surveyed. While the basal area, stem density, richness and Shannon-Wiener index differed significantly amongst phanerophyte types, they were not significantly different between burned and non-burned plots. The sprouting regeneration showed high species diversity for both burned and non-burned plots, higher than equivalent values for mainland of Japanese evergreen broad-leaved forests, but lower than values of a tropical rain forest in southern China. The 1,531 woody stems surveyed in all four plots included a total of 72 species in 50 genera and 30 families. The most common families were Fagaceae, Rubiaceae and Euphorbiaceae. Castanopsis sieboldii, Psychotria rubra and Styrax japonicus were the most important species. C. sieboldii, the primary dominant tree, dominated the sprouting forest with a broad distribution of heights and contributed 54.9 % of the total basal area. The complexity of the layered stratification and high species diversity suggested that sprouting regeneration occurred in a progressive succession, and the stands of both burned and non-burned may evolve into a stand similar to the primary forest before clearcut.
