高水敷切下げ後の樹林化抑制に向けた草本植物の早期植生回復に関する研究

抄録

A control method for suppressing seed germination and seedling growth of willow after lowering terrestrialized floodplains of lowland rivers by land excavation was proposed on the basis of field surveys and document investigations: the germination and establishment of willow may be prevented by facilitating early recovery of tall grasses. The field surveys (308 sites in seven rivers) indicated willow established in lower land level (i.e., land areas near river level) and the relative elevation was 0.54–1.06 m (first and third quartiles). In addition, occurrence probability of willow increased with decrease in the relative elevation from river level. Also, previous studies showed that increasing plant density promptly after the lowering terrestrialized floodplains could be effective for the suppression of the establishment and growth of willow. These findings demonstrated that the relative elevation and plant density were important for the willow suppression.