Abstract
This paper investigates the results approximately 9 years after the application of a method based on spraying of thick growth media in Karatsu City, Saga Prefecture. We compared communities of Chinese-grown Indigofera spp. (CHA-I) and mixed communities of these species combined with evergreen broad-leaved trees (EBLT, using Ligustrum obtusifolium Sieb. et Zucc., Rhaphiolepis umbellata Makino, Camellia japonica L., and Camellia sasanqua Thunb.) on cut slopes. We found that: (1) The EBLT communities can protect slope surfaces as well as forest-floor vegetation even if the canopy is initially completely covered by CHA-I. (2) The density and basal area of CHA-I tended to decline, which suggests that plant succession is occurring towards EBLT communities. (3) The EBLT community, serving as forest-floor vegetation, is effective at keeping green vegetation on the slopes during the CHA-I deciduous season, except when using L. obtusifolium as a semi-EBLT. CHA-I has an average height growth of more than 3 m compared with a height of 0.5-1.0 m Japanese-grown Indigofera pseudo-tinctoria Matsum., even though CHA-I is showing a tendency towards delayed plant succession from a pioneer community towards an EBLT community. Therefore, CHA-I should be considered in revegetation work. The effects of mixed CHA-I and EBLT seedings suggest that it would also be possible to introduce Lespedeza bicolor var. japonica Nakai. and Amorpha fruticosa L. as other leguminous shrubs. This technique can regard as one of the effective slope revegetation technique to solve easily the ecological problems of leguminous shrub communities in terms of the decline of forest-floor vegetation, monospecific forestize, stagnation of plant community succession and landscape problem in the deciduous season.
