Abstract: In order to compare vertical stratification, floristic composition, and woody species diversity of subtropical evergreen broadleaf forests between the Ryukyu Archipelago, Japan, and South China, tree censuses in a 400 m2 plot in Ishigaki Island and a 1225 m2 plot in Dinghushan Nature Reserve were performed. Both of the subtropical forests consisted of five vertical strata. The floristic composition of the Ishigaki forest was quite different from that of the Dinghushan forest in terms of similarity on a species level (Kuno-s similarity index r0 = 0.05). The values of Shannon-s index H' and Pielou-s index J ' tended to increase from the bottom stratum upward in both forests, except H' for the top stratum in the Ishigaki forest and the upper two strata in the Dinghushan forest. The woody species diversity in the Dinghushan forest (H'= 3.01 bit) was much lower than that in the Ishigaki forest (H'= 4.36 bit).
Abstract: The forest stand consisted of four layers. The species
composition between the third and the bottom layers was almost
similar, whereas it was almost exclusive between the top and the lower
three layers. The values of Shannon-s index H' and Pielou-s index
J ' tended to increase from the bottom layer upward, except for
H' -value of the top layer. The values of H' and J ' were 4.21 bit
and 0.73, respectively, for the total stand. High woody species
diversity of the forest depended on large trees in the upper layers,
which trend was different from a subtropical evergreen broadleaf
forest grown in silicate habitat in the northern part of Okinawa Island.
The spatial distribution of trees was overlapped between the third and
the bottom layers, whereas it was independent or slightly exclusive
between the top and the lower three layers. Mean tree weight of each
layer decreased from the top toward the bottom layer, whereas the
corresponding tree density increased from the top downward. This
relationship was analogous to the process of self-thinning plant
populations.