Species Diversity of the Understory Dominated by Dwarf-bamboo Pleioblastus chino Makino in a Secondary Forest with Different Numbers of Years after the Last Mowing

Abstract

In a secondary forest formed by deciduous trees of Quercus serrate Thunb ., three stands of understory dominated by dwarf-bamboo Pleioblastus chino were analysed as a function of the number of years after the last mowing . They were mowed in 1982 (S82), 1987 (S87) and just before the growing season of 1993 (S93). As the time from the last mowing increased, the vegetation height increased but the light intensity in the community and the species richness decreased throughout the growing season in 1993. In these stands , the aerial parts of the plants were harvested and the biomass of each species was determined in the summer of 1994. Species distribution in the community became more uneven as the biomass by P. chino increased with time after the final mowing. The biomass of P. chino accounted for 97% of the stand mowed 12 years ago (S82). In addition, at S82, species richness decreased to one-sixth that at S93. It was found that P. chino, the most dominant species , had a negative effect on species diversity (H'), both in terms of species richness and evenness. Mowing can play a role in controlling important species and the species diversity of the understory vegetation.