Abstract
The purpose of this study was to appreciate the spatial variability of upland soil profile on
complex hillslope and to consider the adequacy of geomorphological information to explain the
soil profile distribution. On a 1.2-ha upland field of central Hokkaido, Soil profile was investigated
at 154 locations on a 14-m grid. Apparent differences were recognized according to
the location on a slope position. In the landsurface model units of Interfluve and Convex Creep
Slope, horizon sequence was Ap/C-type, the color of Ap-horizon soil in this area was relatively
bright and coarse texture. In the units of Colluvial Footslope and Alluvial Toeslope, horizon
sequence was Ap/Ab/B/C-type, the Ap-horizon soil color was relatively dark and fine texture
influenced by sedimentation. Terrain attributes, slope gradient, slope curvature, specific catchment
area etc, calculated from the 7m-digital elevation model were highly correlated with
A-horizon thickness except for slope gradient. Thick A-horizon was observed at the location
which topographic conditions were convex slope, low altitude and high specific catchment area.
The multiple regression model of A-horizon thickness by terrain attributes didn’t have sufficient
result for quantitative tool. However landsurface model units identified the A-horizon thickness
distribution. Geomorphological analisys is useful to guide soil management system with consideration
of spatial variability.
