Seven-year succession of a subtropical laurel forest following strip clear-cutting on Okinawa Island [Japan]

The mortality of stumps and growth of a secondary forest in cut area seven years post strip clear-cutting in a natural subtropical laurel forest on Okinawa Island were studied. The results showed the mortality rate of stumps was 34.7%, which was higher than those in a similar secondary forest at the first and the fifth year after clear-cutting (13.2, 20.2%, respectively) in nearby site, confirming that the mortality rate of stumps increased with years in a certain years. In contrast to dead of one-thirds of stumps nearly, majority of stumps remained alive, of which, 12.8% of the stumps were remained initial figure, 42.6% of them partly decaying and 9.9% of them invisible with living sprout. The secondary forest was consisted of a total of 74 woody species, of which, 49 and 69 species, respectively, were found in sprout- and seedling-origins, greater than that in the primary forest (53 species) before strip clear-cutting. The primary dominant species, Castanopsis sieboldii, still dominated the secondary forest. The mean stem number of seedling origin stems by plot was significant (p 0.05) higher than that of sprouting origin ones. However, no significant differences found for the mean basal area by plot between two kinds of stem origins. Seedling stem number in DBH group 4.0cm had higher values than those for sprout's, while sprout origin stems in basal area were roughly seven-fold more than that for seedling's in DBH group 4.0cm. The results indicated that the seedling stems shared the understorey and sprout-origin stems shared the crown canopy in the early succession stage. The secondary forest was dominated by sprout stems rather than seedling-origin ones. The great of woody species with abundant of sprout- and seedling-origin stems suggested the secondary forest seven years after strip clear-cutting occurred in a progressive succession.