2012 年 16 巻 2 号 p. 71-77
The objective of this study was to investigate the growth factors of grassland plants in semi-natural grassland under artificial management by various mowing frequency per year. As for grassland plants, most species (including the registered species in Red Data Books (vascular plants) of Chiba Prefecture and Ministry of the Environment, Government of Japan) were found at a mowing frequency of 1 time per year, second most commonly at 2 times, and extremely few at 4 or more times. Plant volume of grassland plants was the highest at 0 times (section that has not been mown for over a year), and became lower as mowing frequency increased. Instead, that of ruderal plants was high at 4 and 8 times, and ruderal and exotic plants were only founded at 14 times. The upper rank of dominant species by mowing frequency per year were Miscanthus sinensis at 0 times per year, Solidago altissima, Eccoilopus cotulifer and Miscanthus sinensis at 1 time, Imperata cylindrica at 2 times, Digitaria ciliaris at 4 and 8 times and Paspalum dilatatum at 14 times. As mowing frequency increased, the upper rank of dominant species changed from grassland plants to ruderal and exotic plants, except for Solidago altissima of 1 time. We propose to conduct continuous mowing management that tall herb Miscanthus sinensis community is formed by mowing of 0 times per year, or mesocotyl grasslands including the registered species are formed by mowing of 1-2 times in order to maintain semi-natural grasslands which are historical and cultural landscapes in Shiroi-City, Chiba Prefecture.