Relationship between cover of evergreen species and species richness or species composition of coppice forest in Hokusetsu area, Hyogo, western Japan

Abstract

Coppice forests with various covers of evergreen species were studied to clarify the effect of increasing cover of evergreen species on species diversity and species composition in Hokusetsu area, Hyogo, western Japan. We investigated three communities: Quercus acutissima community which has been maintained by traditional management, Quercus serrata community which was already abandoned and is under progressive succession toward evergreen broadleaved forest, and Quercus glauca community which is dominated by evergreen species in the tree layer. Cumulative cover of evergreen species was significantly correlated negatively with the number of all species in all layers, number of summergreen species in all layers and those in the herb layer. Cumulative cover of evergreen species was significantly correlated with the first axis of Detrended Correspondence Analysis performed for the study plots, which represent differentiation of species composition of the three communities. Species richness per 100m^2 was 50.8 in Q. acutissima community, 41.2 in Q. serrata community and 19.3 in Q. glauca community, showing a difference between communities. Summergreen species counted 33 in 38 indicator species for Q. acutissima community, 11 in 15 for Q. serrata community and 2 in 11 for Q. glauca community, respectively. It is considered that degradation of light conditions, originating from the increase of evergreen species, inhibits the growth of shade-intolerant species, resulting in decrease of species richness and changes in species composition.