Effects of dynamic site conditions on plant succession in the riparian area with a large-scale collapse in the upstream area

点击翻译按钮获取中文摘要

The purpose of this research is to clarify the influence that the dynamic site condition impacts on the plant succession in the riparian area that has a large-scale collapse place in the upstream area.Investigation area is on the riparian area in Ohya River, the upper reach of Abe River, which sediment transport is constantly expected, because the place has a large-scale collapse in the upstream area. The plant community structure and the succession were surveyed and the area of the disappearance and recovery of the forest place were investigated by the aerial photograph interpretation. In addition, the influences that the frequency and the strength of the disturbance that made rainfall an index influence on the succession were discussed.Based on the species composition and sere the forest in the research sites was classified in the 4 stages. The first stage is community of pioneer species, Alnus filma, Alnus maximowiczii, Salix sachalisesis and passed 10 years from the period of invasion and has not experienced the 10-30 year probability rainfall (400-500mm) yet. However, the stands that are advanced to the second and third stages have experienced the probability rainfalls. The second stage is 10 to 25 year three-story forest, next-generation species-Carpinus in the middle story, Quercus mongolisa var.grosscratta and Acer forming the ground story under the canopy of pioneer species. The third stage is 25-45 year old stand dominated by side species and Acer species in the ground story. The fourth stage is 45 year or above forestland covered mostly by Acer species. As a result of this research, it became clear that riparian plant communities in Ohya River is related with the intensity and frequency of disturbances.