IMPROVEMENT ON THE GROWTH ENVIRONMENT OF ENDANGERED SPECIES

Abstract

Vallisneria higoensis which is an aquatic plant peculiar to Kumamoto Prefecture is on the verge of the present extinction. In this study, it aimed at an improvement of the growth environment of a water plant by making the flow velocity increase using groyne. The indoor experiment considered groyne arrangement. Consequently, it turns out that the one-bank groynes increases the flow velocity of a mainstream part by about 5% compared with a case without a groyne, and it is increasing about 10% in the both-banks groynes. It was admitted by the result of a field survey that the flow velocity in main flow region after both-bank groynes installation was increasing about 11 to 23% compared with before installation. It turns out that 5m distribution expansion was seen at the maximum about growth of aquatic plant, and the area of a aquiherbosa is also expanded.