Revegetation of an artificial cut-slope by seeds dispersed from the surrounding vegetation

Abstract

We examined a method for revegetation of cut-slopes in Tochigi, Japan, using only natural plant dispersal from the surrounding vegetation. We examined plant establishment in six plots in a cut-slope in bedrock (inclination: 65°, direction: S45°W) treated with various types of netting and fertilizer. We surveyed the plant communities, individual trees, and seed rain on the cut-slope, as well as the plant community on the undisturbed upper slope. Revegetation method using polyethylene netting with fertilizer and water-retention material was the most effective. The resulting plant community was dominated by Pinus densiflora, with a cover of 49.0±11.4% after 5 years. This plant community consisted of 19 species, including ten tree species and a density of 26.2 trees/m2. Revegetation method using palm-fiber netting with fertilizer also resulted in high plant cover after five years, although little revegetation grew on this plot in the earlier years. The roughness of the palm fiber may have inhibited revegetation. Application of fertilizer was essential for the success of this natural revegetation method. In addition, the revegetated plant community was strongly influenced by seed rain from the vegetation of the upper slope. The number of trees that became established was much lower than the number of tree seeds that were dispersed, possibly because of the absence of soil. We recommend that soil is allowed to accumulate or that a base of material to facilitate plant growth is added. Successful revegetation was achieved even under the harsh conditions of this cut-slope.