Abstract
Pleioblastus chino var.viridis can dominate under severe grazed conditions. To understand the reason for this dominance, we investigated the dry matter composition ratio of each part in the plant body and dry matter production in two plots;grazed and ungrazed. Leaf production and grazed mass during a grazing period were estimated using a regression formula between the standing crop of leaf and the leaf increase rate. The dry matter composition ratio of rhizome in the grazed plot was higher than that in the ungrazed plot. On the other hand, the ratio of stem in the grazed plot was lower than that in the ungrazed plot. The ratio of leaf in the grazed plot was almost equal to that in the ungrazed plot during the grazing period. Annual net production in grazed and ungrazed plots was estimated at 670gDM/m^2 and 647gDM/m^2, respectively. From the obtained results, we consider as follows. The increase in composition ration of rhizome under grazed conditions has the advantage of increasing the security of the bud and the storage of reseve substance for regeneration of leaves after a disturbance. Thus, the increase in the ratio of rhizome with the decrease in stem contributed to active leaf production and high annual net production. The high net production under grazed conditions enabled the dominance of P.chino var.viridis to occur.
