Influence of seeding exotic pasture grasses on the vegetation recovery of landslide slopes formed by typhoon 9512 in Mikura-jima Island, Izu Islands, Japan

Abstract

1995 9 12 −1 Castanopsis sieboldii (Makino) Hatusima ex Yamazaki et Mashiba Machilus thunbergii Sieb. et Zucc. Eurya japonica Thunb. Buxus microphylla Sieb. et Zucc. var. japonica (Muell. Arg. ex Miq.) Rehd. et Wils.

Influence of Fertilization on Native Plants and Exotic Pasture Grasses on the Fascined Landslide Slopes in Mikura-Jima Island, Japan

“…However, the decrease in mean plant density cannot be explained, because the plots were not covered completely by A. sieboldiana; that is, the self-thinning is not expected to be caused by competition between individuals. The Trino-o No.3 landslide slope might be a severe environment for A. sieboldiana, as we observed lodging or slanting of trees in 2007 [1].…”

“…Analysis of co-variance did not detect significant differences in the regression coefficients between the non-fertilized and fertilized plots. Previously, we reported that individual D0 2 H was greater in fertilized plots than in non-fertilized plots based on data collected from 2004 to 2009 [1], but those differences diminished by 2013. This extended data set indicates that a single fertilization increased individual D0 2 H of A. sieboldiana with effects apparent for several years but diminishing in 10 years.…”

“…et Zucc.) [1]. The thin layer of volcanic ash soil was washed away, and the bedrock was exposed on the landslide slopes.…”

“…the island. On this slope, exotic pasture grasses were seeded by helicopter after the localitycertified seedlings had become established ( Fig.3 and Fig.4); subsequently, the vegetation of the slope transitioned to a grassland community dominated by exotic pasture grasses in the next year [1], [9]. Then, in 2004, study plots were established, and one treatment group was fertilized once with fowl manure at 0.2 g/m 2 in order to support the growth of planted native seedlings which had inferior growth (Table 1).…”

“…For future disaster prevention, it is desirable to transition from exotic pasture grasses to native species. However, exotic pasture grasses have been reported to prevent vegetation recovery: they prevent the establishment of trees [1], [4], change the direction of early succession [15], and may dominate the vegetation for long periods, e.g., 20 years [5], [8], [11], [15].…”