Field surveys on plant species richness and soil chemistry were carried out at 30 study sites in “Satoyama” deciduous forests and coniferous plantations in Ichikai Town, Tochigi Prefecture, Japan. In deciduous forests, tree (height > 1.5m) species richness showed significant positive correlation with the period after abundance of vegetation management, and with soil electric conductivity. Herb-layer (height < 1.5m) species richness showed the just opposite tendency to tree species richness. Analysis of covariance indicated that soil electric conductivity could cause difference in species richness of both trees and herb-layer species regarding the period after abundance of vegetation management as covariate. Soil electric conductivity was lower at the sites where litter was removed in the last vegetation management than the other sites. Two possible underlying mechanisms behind the observed correlation among soil electric conductivity, species richness and the period after abundance of vegetation management were discussed: one is nutrient accumulation by decomposition of litter that may increase interspecific competition, and the other is safe site elimination by litter deposition. It is concluded that removal of litter in vegetation management plays a role in keeping herb-layer species richness relatively high.
