Spatial Variation of the Plant Communities and Microscale Landform in the Floodplain of the Kokai-gawa River

Abstract

The relationship between spatial variation of plant communities and microscale landform was surveyed and analyzed in the floodplain of the Kokai-gawa River, Ibaragi Prefecture. Environmental factors influencing the relationship was also discussed. In hollows in the floodplain, the distance between the surface of the earth and that of groundwater was short, and Miscanthus sacchariflorus or Phragmites communis was dominant in plant communities. On high grounds or slopes without hollow, the level of groundwater was low and woods or herb communities were established. The latter was often observed on the areas where trees were cut recently. The harder the soil was the less the frequency of species that occurred in woods were. From the results, it was indicated that the groundwater level and the hardness of the soil were major environmental factors influencing the plant communities in the floodplain. It was pointed out that the land use that was appropriate to the microscale landform and the management of human impact on the plant communities were essential.