Invasion of bamboo,especially of the imported species Phyllosachys pubescens from China,into mixed forest may result in reduced soil development,land slide and destruction of species diversity in the forest ecosystem.This is due to infiltration of the previously existing forests by bamboo,which had been left without trimming,but was once cultured for food and construction materials.Extinction of broadleaf trees by this rapid bamboo growth may change soil thickness,composition,and concentrations of nutrients,and result in degradation of the forest and deterioration of the ecosystem.This paper is a preliminary report of changing soil compositions related to bamboo invasion,to emphasize the importance of soil fornlation by broadleaf trees.