寒冷気候と土壌北海道北部の気候と土壌地理学的特微 (寒冷気候にまつわる諸問題(特集)) -- (寒冷気候下の現象)

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This paper describes the results of investigation on the relation between the climate and soil geographical characteristics of the northern Hokkaido. In order to make clear the effect of climate on the soil formation, heat balance climatological methods have been applied. The results obtained are summarized as follows.1) In the northern Hokkaido, the annual value of the net radiation is in the range from 32 to 35 kcal/cm2·yr and monthly maxima (7±0.5kcal/cm2) appear in the early temperate season (May-July). Judging from the close relation between the net radiation and latent heat flux and annual summations of daily mean temperature (>10°C), it is concluded that the net radiation is a fundamental element which reveals the thermal condition of the environment.2) The atmospheric humidity is estimated quantitatively by the radiative dry index, that is the ratio of the net radiation to the amounts of heat required to evaporate all of the annual precipitation. Because of the remarkable local variation of the annual value of precipitation, considerable discrepancies of figures among meteorological observatories are noted, though the annual value of heat balance components is almost constant throughout the area.3) The area where the annual mean value of the radiative dry index is less than 0.5 coincides very well with the zone of weakly podzolized soils. The climate of this area differs apparently from that of the continental zone of podzolic soils which were described by MA et al (1958) and BOROBUEV (1963). Generally speaking, the climate of the northern Hokkaido is warmer but more humid than that in the far eastern districts of continental Asia.4) Seasonal dynamics of the hydro-thermal condition is controlled by the thawing and water deficit (precipitation minus potential evapotranspiration) during the eary temperate season. Judging from the occurrence of high annual precipitation, prolonged thawing season and scanty net radiation in the late temperate season, it is concluded that the leashing out water regime is continued almost through the year in the podzolic zone of Hokkaido unless the low permeable layer in the profile prevents the deep percolation of excess water. However, in the central and southern seaboards of the Okhotsk where dry climate during the early temperate season is evident, the downward movement of water through the profile is strongly reduced during the period from April to July. Consequently, the water regime in the area tends to become the periodical leaching out water regime. The main reason of the soil geographical zoning in the northern Hokkaido might be attributed to the cool-humid climate and its local or seasonal variation as described above.5) It should not be overlooked that the formation and composition of catenary associations on flats and depressions of terraces or subdued terrains are also affected by the cool-humid climate and poor internal drainage of the sediments.6) Furthermore, one has to point out the influence of the climate as it is highly probable that the main soil parent materials on uplands and hills, such as consolidated tuffaceous clays and slope sediments, were made under the cryopedological processes occurred during the past cold and humid ages.
日本第四紀学会の論文

寒冷気候と土壌北海道北部の気候と土壌地理学的特微 (寒冷気候にまつわる諸問題(特集)) -- (寒冷気候下の現象)

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寒冷気候と土壌 北海道北部の気候と土壌地理学的特微 (寒冷気候にまつわる諸問題(特集)) -- (寒冷気候下の現象)

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寒冷気候と土壌北海道北部の気候と土壌地理学的特微 (寒冷気候にまつわる諸問題(特集)) -- (寒冷気候下の現象)