Abstract
We conducted a phytosociological survey in the primeval lucidophyllous forest of Kawanaka, Aya, Miyazaki Prefecture in 1988. Since the 1990s, the population density of the Sika deer (Cervus nippon) has increased, and their feeding pressure on vegetation has been conspicuous. In 2009, we conducted a phytosociological survey in primarily the same stands as in 1988 to compare the layer structure, the species richness and species composition of the forest in 1988 with those in 2009. The coverage of the second shrub layer and the herb layer was decreased significantly by feeding pressure. Species richness in the second shrub layer significantly decreased; however, there was no significant difference in that of the herb layer. The species richness of four life forms, i.e., lucidophyllous tree, lucidophyllous small tree, lucidophyllous shrub and terrestrial herb significantly decreased. The total number and the mean number of component species of the lucidophyllous forest decreased from 109 and 60.3 in 1988 to 92 and 45.6 in 2009, respectively. The numbers of species that decreased and increased in frequency or coverage between 1988 and 2009 were 25 species and 6 species, respectively. Representative decreased species were Trachelospermum asiaticum var. intermedium, Ardisia pusilla, Rubus buergeri, and Diplazium subsinuatum. On the other hand, the 12 species, including Actinodaphne longifolia, Ardisia crenata, and Arisaema japonicum, were considered to be unpalatable plants by studies from other regions. This investigation clarified that feeding pressure of Sika deer was responsible for the changes in the layer structure, species richness and species composition of the primeval lucidophyllous forest.
