飛騨地域の山間休耕田における植生遷移

抄録

Several studies have attempted to clarify the plant succession of fallowing paddy fields, Particularly in plain regions. Here, we investigated this subject with special reference to small-scale terrace paddies in mountainous regions. Sixteen sites differing in fallow duration and/or soil moisture conditions were examined, and temporal changes in vegetation were observed using biological spectra based on SDR_s. In dry fields, the secondary succession showed basically the same tendency as that in plain regions, although an exception was seen during an invasion of solidago altissima. In wet fields, secondary succession was more complicated than that in plain regions, and was accompanied by a great fluctuation in biological spectra. This is considered to reflect the extremely localized heterogenity of soil moisture conditions. The SDR of aquatic plants showed a relatively high percentage in wet fields, but was never dominant. In this case, the succession was characterized by the dynamics of annual Polygonum spp. and shallow-rooted perennials such as Oenanthe javanica, and by an absence of large rhizomatous geophytes such as Typha latiforia and Phragmites communis. The succession under study seemed likely to be affected by surrounding vegetation, including woody species, irrespective of soil moisture conditions.