2008 Volume 25 Issue 1 Pages 63-72
A lucidophyllous forest on Mt. Omoridake, Aya, Miyazaki Prefecture, was studied in order to clarify the relationship between host tree size (height and diameter at breast height [DBH]) and species richness of the epiphytes on each tree. In this forest, a total of 133 trees (14 species), including 44 Quercus acuta, 23 Distylium racemosum, 22 Persea thunbergii and 44 others, were chosen as sample trees. The epiphytes on the sample trees comprised 22 species, including Lemmaphyllum microphyllum, Lepisorus onoei, Bulbophyllum drymoglossum, and Davallia mariesii. The species richness of the epiphytes on each sample tree had a high positive correlation with tree DBH (cm). This relationship was expressed by the equation: y=0.11x-1.77 (where y is the number of epiphytes, and x is the DBH (cm) of the sample tree). Species composition and species richness of the epiphytes were compared between a highland lucidophyllous forest (Omoridake) and a lowland lucidophyllous forest (Kawanaka). The ordination obtained by detrended correspondence analysis (DCA) by using all occurring epiphytes revealed that the epiphytes on the sample trees (stands) in the highland were clearly different those on the sample trees in the lowland. The lucidophyllous forest in the highland was characterized by the occurrence of L. onoei, D. mariesii, B. drymoglossum, and 9 other epiphyte species, while that in the lowland was characterized by the occurrence of Lepisorus thunbergianus, Neofinetia falcata, and 5 other species. Thus, there was significant difference in the species composition and species richness of the epiphytes between Omoridake and Kawanaka. Higher species richness of epiphytes in the highland forest appeared to the result of relatively higher air humidity at the high altitude.
