草地の状態診断に関する研究 II : 種類組成による診断

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1) Types or seral stages of grassland vegetation are characterized by two methods: dominant and charcteristic species. Then the judgement of grasslands by the floristic composition is done from such two viewpoints. 2) The dominant is the greatest species in "dominance" in a community at a time. The dominance is expressed by the cover and height ratio as the summed dominance ratio (SDR) and the relative dominance (SDR'), or the multiplied dominance ratio (MDR). They are culculated by the summation or multiplication of the ratios of cover (C') and Height (H'), namely, SDR=(C'+H')/2% and MDR=(C'×H')/100% (Table 1). The constituent species are sometimes treated as superspecies or ecological group of seral equivalents, for example, Lespedeza bicolor superspecies. Japanese main types of mesophytic grassland used for grazing and mowing are Miscanthus-, Zoysia-, Pleioblastus-, Sasa-, Pteridium-, and Poa pratensis types, addition to these, Imperata- and Cynodon types when we consider them including tropical and subtropical grasslands. The establishment and dynamics of a grassland type is shown in Fig. 1 by an example of Miscanthus type grassland. And we can often recognize mixed types of main grassy species as the co-dominants (Table 2). They are pools of pure types or precursory types of grassland and become special, simple types under the biotic pressure. The competitive relation of such pure types is determined by some outer influences, i.e. biotic pressure and climaitc condition. For the ecological judgement of grasslands in detail, the autecology of main grassy species, especially their life history and vitality will be important. 3) The judgement of grassland condition by the characteristic species is connected with the plant indicator. Phytosociological studies on the classification of grassland vegetation are very few. Here some pioneer works and the author's studies are reviewed. The presences of constituent species of Miscanthus type grassland are examined (Table 3). The value of plant indication is restricted in case of local characteristic species. Arborescent species appearing in the course of grassland succession are shown in Table 4. In Japan the course of succession and corresponding species are closely connected with the climatic regions.
日本草地学会の論文
1966-05-30

草地の状態診断に関する研究 II : 種類組成による診断

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