Characteristics of a 20-year-old evergreen broad-leaved forest restocked by natural regeneration after clearcut-burning

To elucidate the application of natural regeneration to the restocking of evergreen broad-leaved forests in the subtropics, the characteristics of a 20-year-old evergreen broad-leaved forest restocked by natural regeneration after clearcut-burning were studied in Okinawa, Japan. Within a 0.87 ha clearcut area with four 10 m x 10 m sampling plots, two burned and two unburned ones, the tree composition, tree species diversity and vegetation changes were investigated. The results showed that the species diversity, basal area and density of woody stems >= 1.0 m in height differed significantly among phanerophyte types, while they were not significantly different between the burned and unburned treatments. A vegetation census also revealed no obvious differences between the treatments. The primary dominant species, Castanopsis sieboldii, continued to dominate the secondary forest with a broad height distribution. The structural complexity and high tree species diversity of the regenerating forest after clearcut-burning provides no evidence of degeneration. We can predict that the regeneration forest may gradually develop into stands similar to pre-clearcut primary forest, and that natural regeneration may restore the high tree species diversity of the evergreen broad-leaved forests in Okinawa.