A study on change of vegetation in sediment deposition areas of check dams and prediction of its succession

位于兵库县南部的六光山被选为本研究区域。利用航片判读法，对1928 ~ 1999年间国土交通省修建的淤地坝淤积区植被变化进行了调查。利用1969、1979、1989和1999年的航片和1 ~ 2000比例尺的地形图，对泥沙淤积区植被进行调查。淤地坝建成后的年限越短，更新速度越快。随着沉积面积的增加，森林面积比例呈下降趋势。在京都县和知町、绫部市的17个淤地坝和六甲山进行了实地调查。在沉积区，调查了植物种类、微地形、土壤类型和日照。由于沉积区土壤粒径较大，土壤持水能力较原坡面弱，沉积区土壤较原坡面趋于干燥，土壤肥力较原坡面低，植物演替速度较慢。在此基础上提出了沉积区植物演替的模式。

The Rokko Mountains located in the southern part of Hyogo Prefecture was chosen as this study area. Change of vegetation in sediment deposition areas of check dams which were constructed by the Ministry of Land, Infrastructure and Transport from 1928 to 1999 was surveyed by aerial photograph interpretation. Aerial photographs taken in 1969,1979,1989 and 1999 and topographic maps drawn on a scale of one to twenty hundred were used for investigation of vegetation in sediment deposition areas. The years after completion of check dams are smaller, the regeneration are faster. As the size of deposition areas increases, the rate of forestry area tends to decrease. Because if the deposition areas are larger, changes of river bed and water course occur frequently, and the areas suitable for grassland increase.Field investigation was conducted at the 17 check dams in Wachi Town and Ayabe City, Kyoto Prefecture and the Rokko Mountains. At the deposition areas, kinds of plants, micro-topography, types of soil and insolation were surveyed. As the grain size of soil is larger and water holding ability of soil in the deposition areas is weaker than original slope soil, the soil in the deposition areas tends to be dry compared with original slope soil The soil fertility is also lower than original slope, the pace of plant succession is slower. A model of plant succession at the deposition areas was proposed based on this research results.