The Distribution of Viola L. in rural area of Iwate [Japan] Prefecture and the influence of the difference of management on the population density of Viola spp
2010
Takeda, S., Iwate-ken. Agricultural Research Center, Kitakami (Japan)
There were eight species of Viola L. (V. rossii, V. rostrata var. japonica, V. kusanoana, V. grypoceras, V. obtusa, V.mandshurica, V. betonicifolia var. albescens and V. verecunda) present in rural area of Iwate Prefecture inland part. A species composition was different in five types of landscapes (Forest floor on the hill zone, Forest edge on the foot hill, Forest edge by the farm pond, Farm pond-side grassland and Paddy-side grassland). A species composition seemed to change corresponding to the light factor and soil moisture of the landscape. At the abandoned paddy-side grassland and the abandoned farm pond-side grassland, the frequency and an individual density by the ocular estimation of Viola spp. was very low in comparison with either grassland that continuous grass-cutting management. The stop of the grass-cutting and the water management caused the decline of the species diversity. It seems that continuous cultivation and grass-cutting management must be maintained to sustain specific density of Viola spp. At the improved farm pond-grassland, the number of the species of Viola spp. was a few than that in the traditional farm pond-grassland, but the frequency and an individual density was equally in comparison with paddy-side grassland that continuous grass-cutting management. It thought about the environmental heterogeneity of the farm pond, such as forest edge, with the cause that a species-diversity was being maintained.
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