吉野川め砂州上におけるヤナギ群落およびアキグミ群落の分布と立地特性

抄録

Distribution of Salix spp. community and Elaeagnus umbellata community on bars was surveyed in middle and down reaches of Yoshino River, Shikoku, Japan and recorded on 1:5, 000 map. Physical conditions of bars, namely distance from the river mouth, width of bars, mean maximum size of bar-bed materials and elevation, were also detected through field survey and checking cross-sectional data measured by the Ministry of Construction of Japan.
The abundance of both communities at an every bar was quantified by two methods; mesh and line-transect methods. The reliability of line-transect method to know relative abundance of the communities in a large area was confirmed by comparing the results of two methods.
As the result of multiple regression analysis, the abundance of each community could be explained by using some physical factors. The width of Salix community appearing on a transect line can be expressed in terms of a bar width and its partial widths divided by elevation intervals of one meter. The width of Elaeagnus umbellata can be expressed in terms of mean maximum size of bar-bed materials and the partial widths of a bar divided in every one meter elevation.