PARENT SESSION
Poster Session 19: Biodiversity
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Woody species diversity and spatial distribution of trees in relation to the stand stratification of a subtropical evergreen broadleaved forest, Okinawa Island, Japan.

FEROZ, S. M.^*,1, HAGIHARA, AKIO ¹, YOKOTA, MASATSUGU¹, ¹ Laboratory of Ecology and Systematics, Nishihara-cho, Okinawa, Japan.

ABSTRACT- On the basis of stand stratification, woody species diversity, species composition and spatial distribution of trees in a subtropical evergreen broadleaved forest, growing in a silicate area, were investigated in a plot of 30 m × 25 m. A total of 26 families, 43 genera, 60 species and 4684 individuals were encountered. The diversity index H ′ and equitability index J ′ were respectively 4.82 bit and 0.81 for the stand. The forest showed a high diversity, which was comparable to those of subtropical forests grown in a limestone area. The forest stand was stratified into four layers. The values of H ′ and J ′ increased with decreasing height of the layers except those of the bottom layer. It was shown that the diversity index H ′ for the total stand should be measured over a minimum sample area of 200 m². Castanopsis sieboldii (Mak.) Hatusima was the most dominant species in terms of importance value and it was appeared over the four layers, having the highest importance value. The expected maximum number of species was 62 per plot in the total stand, and 36 in the top layer, 46 in the second layer, 59 in the third layer and 64 in the bottom layer. The spatial distribution patterns of trees for the total stand and for each layer except the top layer were found to be a single individual-completely random distribution. In the top layer, there seemed to exist a triple-clump structure. Most of the species were common between the second and the third layers, and half of the total number of species was common between the top layer and the other three layers. The degree of overlapping showed that the spatial distribution of trees was almost overlapped between the second and the third layers and it was nearly overlapped between the top and the other three layers.

Key words: Expected number of species, Importance value, Silicate area, Species similarity