砂礫河原に繁茂する株状草本シナダレスズメガヤの土砂捕捉特性と洪水攪乱による除去条件

抄録

Initial process of forestation in a river is affected by perennial grasses because they accumulate much amount of sediments and nutrients at flood events. The growth dynamics of Eragrostis curvula, a colony-type and invasive grass, was investigated for elucidating the relationship between the plant dynamics and the sand deposition on a river bar. Shields parameter of the gravel around the plants was calculated using the roughness characteristics of the plants and friction velocity obtained by field measurement and wind tunnel experiment. Eragrostis curvula accumulates more sediment in proportion to the increase in the colony diameter. The growth of Eragrostis curvula in the next year of flood distmbance was changed according to the diameter of the colony. Removal condition of Eragrostis curvula by natural flood sat the field observation site was evaluated as a function of the colony diameter and its density.