抄録
This study aims to relate phenomena of bare groud distribution with land condition in a fixed dune area in south western Niger. For that purpose, a geomorphological and pedological survey as well as that of the bare grounds were carried out. The results were as follows.
1) The study area was mainly divided into plateau and pediplain, where sand covers distributed with various depth. The soil types of each landform unit were characterized mainly by depth of sandy layers.
2) Four types of bare grounds were recognized in the study area ;(1)tiger bush type, (2) termite mound type, (3) wind erosion al type, and (4) slope-related type. The former two were considered as naturally -formed bare grounds, while the latter two as mainly human induced ones.
3) The rate of bare ground occupation increased considerably from 1975 to 1992, and their distribution was localized on the areas without sand cover (plateau) and with relatively thin sand cover (pediplain), and on the sloped areas with about 4% of gradient.
4) Depth of sandy layers, which may decide depth of effective layers for plant growth, was considered as one of important factors controlling phenomena of bare ground formation.
