In Japan pedology and phytosociology have started nearly at the same time little before or after 1930. Owing to the climate characterized by the heavy precipitation, the influence of climate upon soil and vegetation is predominating, so that the mutual relationships between the two latters are concealed behind the controling effects of the former, and to our regret the two sister sciences have developed rather independently in Japan. It will be worth while now to show a vision of a phytosociologist over the mutual influences between the Japanese soil and vegetation. This is not a conclusion, but a forecast. I have induced some not yet firmly proved phenomena into the treatise, which will be later proved substantially. Any advise and criticism from the pedologists' side is welcomed. The warm-temperate broad-leaved evergreen forest of Japan, the alliance of Shiion Sieboldi by the writer is a characteristic plant-community in the Northern Hemisphere, because it has no corresponding community both in Europe and in America. It is a temperate rain forest connecting the deciduous beech-climax to the North and the subtropical rain-forests in the Southeastern Asia. The soil under these broad-leaved evergreen forest, both in the warm-temperate and the subtropical, has in general A-horison with higher pH-value than the underlying B. Consequently we shall call it the Shiia-type soil, separating from the soil under the beech forests in the cool-temperate climate, although the two types are included into the same type of brown forest soils by the other authors. The precipitation increases southward along the archipelagoes lying along the eastern coasts of Asiatic Continent, but the hydrothermal relationship sometimes tends drier, thus we can find local drier districts. In Setouti districts Quercus phillyraeoides A. GRAY, vicarious species of European Q. ilex L. makes a sclerophyllous forest and olive is cultivated in Syodo Island. To the leeside of the winter monsoon, which brings rain or fog between 22° and 31° N we can find drier climates characterized by the Cycas revoluta scrub, Pinus liukiuensis-Cyacas revoluta savannah-like vegetation and deciduous forests of Acacia and Bombax. Although belonging to the group of brown forest soils, the soils under the Japanese beech forest, the alliance of Fagion crenatae, has the acid raw humus and Japanese beech, Fagus crenata BLUME seems not prevent the podzolization tendency of the underlying soil. It is not surprizing, however, when one thinks of the high amount of rainfall in Japan, that the actual amelioration of acidity was concealed by the leaching of heavy rainfall. Nevertheless, the amelioration effect do exist, because in the area of the warm temperate forest we can find the Shiia-type forest soil with A-horison containing less acid humus. In Japan, serpentine and lime plants or plant-communities are also studied, but there exist characteristic plants on volcanic ash. Small-leaved dwarf bamboo, Arundinaria chino MAKINO in East Japan and A. pygmaea MITFORD in the West and bracken fern, Pteridium aquilinum KUHN indicate deep accumulation of volcanic ash. On the contrary Pinus densiflora SIEB. et ZUCC. is not vigorous on the volcanic ash, while P. Thunbergii PERL. sometimes shows preference to it. Among the broad-leaved evergreens, Shiia species are sometimes lacking on the volcanic ash. They may be called negative indicators of volcanic ash.

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Some considerations were made on the clay-fractions of the fresh volcanic ash soil on the foot of Asama Volcano, especially from the genetical point of view. 1. In spite of the immaturity of the soil, strong eluviation of silica and bases have occurred in the clay-fractions present only in minute content, and allophone has been already formed. In other words, the characteristics of volcanic ash soil can clearly be recognized for the age of the soil. 2. From the remarkable increase of Al_2O_3 contents in clay-fractions and gradual but regular increase of clay contents down the profile, it is concluded that the downward translocation of Al_2O_3 has taken place in the profile. And in this translocation, fulvic acids are sure to play an important role, including the destruction of alumino-silicate in the surface horizon. This process is apparently podzolization. 3. Free iron oxides, on the contrary, are concentrated in the surface horizon and old surface horizons of buried soils. This residual concentration of Fe_2O_3 is thought to indicate the peculiarity in the occurrence of podzolization process in volcanic ash soils. 4. In the uppermost horizon and surface horizons of buried soils, there is supposed the existence of poorly crystallized halloysite, while allophone is dominant in lower horizons. The writer pointed out the possibility that the formation of halloysite was caused by podzolization. 5. Together with the peculiarity of the nature of parent material, the action of fulvic acids seems also to promote the formation of clay having narrow silica-alumina ratio, especially in lower horizons. 6. It is thought possible that the apparent expressions of podzolization in the profile are the reflection of the given bio-climatic condition (subboreal). However, further investigations are needed for the solution of this problem.

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This paper deals with composition of humus found in Humic Allophane soils derived from volcanic ash in Japan and with relationships between Ch/Cf ratios of humus and the bioclimatic condition of the soils examined. Two analytical methods devised by I.V. TIURIN (1951) and V. V. PONOMAREVA (1957), respectively, were previously examined to compare with suitability for Humic Allophane soils in Japan. The method of PONOMAREVA gave relatively lower values of Ch/Cf ratios than did the method of TIURIN. This is explained by the fact that the amount of N H_2SO_4-hydrolyzable fraction was added to the fulvic acid fraction according to the method of PONOMAREVA, whereas that was not added to the fulvic acid fraction according to the method of TIURIN. The amounts of the fraction 2 bound with Ca obtained by the method of PONOMAREVA were often inconsistent with actual Ca-status of Humic Allophane soils. Therefore, the method of TIURIN has been used in the present study. Analytical data showed that a majority of humus were bound with both sesquioxides and allophane and amounts of the fulvic acid fraction gradually increased with depth. Young Humic Allophane soils (sample Nos. 1 and 8) have lower contents of carbon and relatively larger amounts of the fulvic acid fraction than do old Humic Allophane soils, indicating that condensation and polymerization of humic acids and the carbon content of the soils increase with the proceeding of pedogenetic process. Ch/Cf ratios of humus separated from twelve surface horizons of Humic Allophane soils distributed in the subboreal and humid subtropical zones are as follows: [table] As a result of the above-mentioned examination and the literature investigation on humus of volcanic ash soils developed on the arctic zone (for example, "ZONN et al., 1963), the writers would like to propose a working hypothesis that Ch/Cf ratios of humus found in Humic Allophane soils have higher values in the humid subtropical zone than in the boreal and the humid tropical zones, though the data for Ch/Cf of corresponding soils in the humid tropical zone have not yet been available. Ch/Cf ratios of humus found in Humic Allophane soils are quite different from those in Red-Yellow soils associated with Humic Allophane soils in the same bioclimatic zone, indicating that there is a clear evidence of intrazonality for Humic Allophane soils.

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