抄録
The attempt to restore forest after construction work has been conducted. In most case, the mixture of soil material and seeds was sprayed to cover naked land. Similar methods have been applied for the greenery on surface rock al-though sprayed soil was rapidly fell down several years after spraying. In this paper, greening methodology on the steep slope formed on the surface rock exposed to gather rock was studied. The reforestration of steep slope face (1:0.8) required the development of new greening technology including the selection of plant species, treatment of the surface of rock (formation of root-bed), introduction of seedlings instead of seeds of grasses. The field survey was also conducted to determine the soil mixture used for the spraying method. The field test with small scale was also conducted on site. These results indicated that inorganic materials (soil or sand) were more suitable than organic materials as soil materials. For the planting of seedlings (2-3 years old), it was necessary to prepare small cavities (root-bed) on the surface rock to support root elongation of seedlings. Three experimental plots (400 m2 each) were selected with varied soil texture, weathering stage, spring water availability, and number of cracks. One year after plantation, the survival rates of seedlings were 46.6% on low weathered surface rock as compared to those of 71.3% and 76.6% of high weathered surface rock with exuding spring water, respectively. Based on these results, reforestration methods to create natural forestry were discussed.
