Distribution Pattern of Amphibian on Rural Landscape in the Middle Reaches of the Oita River, Northeast Kyusyu

Abstract

This study aimed at acquiring the knowledge about the distribution pattern of amphibians on the rural landscape in the middle reaches of the Oita River. Here were recognized two URODELA species and ten ANURA species, twelve species of amphibians in total. In the running water area, Hynobius naevius and Rana tagoi inhabited in streams of a headwater in wooded regions, and Buergeria buergeri inhabited only the main current of the Oita River. In standing water area, the subject of our investigation was classified into the extensive distribution species, Hyla japonica, R. nigromaculata and Rhacophorus schlegelii, the uneven distribution species, R. limnocharis, R. rugosa, the limited distribution species, Cynops pyrrhogaster, R. ornativentris, and the rare species, Bufo japonicus, R. japonica. Especially the limited distribution species were guessed to be under the influence of the distribution restrictions by the altitude and the ability to colonize upper paddy fields. The distribution of each species corresponded to landscape elements relevant to the wetlands from the hillside to the Oita River, much the same pattern applying to every part of the three target basins. We were able to clarify the relationship between the landscape structure and the amphibians in this target rural district which mainly consists of step-like paddy field.