石灰岩の不溶性残渣は微量であることから,石灰岩上に生成する暗赤色土の土壌母材が何であるか長年問題とされてきた。本論文では,大垣市金生山および石垣島真栄里に生成する暗赤色土の性状と母材について検討した。金生山および真栄里の石灰岩を1mol L^<-1>酢酸処理した不溶性残渣は,それぞれ6および318gkg^<-1>であった。また,ESR法による酸素空格子信号強度は,両土壌中に含まれる微細石英が風成塵由来であることを示した。さらに,金生山土壌ではアカホヤテフラの影響もみられた。土壌理化学性には石灰岩の影響が認められた。また,粘土鉱物組成には石灰岩や気候条件下での風化作用も現れていた。従って,金生山土壌の母材は均一ではなく,主要母材を風成塵とし,石灰岩の残渣とアカホヤテフラが加わり,暖温帯での土壌生成作用を受けて生成した暗赤色土であると考えられた。また,真栄里土壌も均一の母材からではなく,風成塵と石灰岩がともに主要な母材となり,亜熱帯気候の土壌生成作用を受けて生成した暗赤色土であると考えられた。

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The ESR-signal intensity associated with the oxygen vacancy in the silt sized fine quartz and the clay mineral composition were examined, in order to investigate the influence of eolian dust on the parent materials in two Red-Yellow soils developed on the bedrock of Tertiary sediments and two Dark Red soils on the bedrock of the Tertiary Ryukyu limestone, in Yonaguni island. The results summarized as follow: In the A, Bw1 and BC horizon of a Red-Yellow soil, Kubura (KUB) soil, ESR-signal intensity of fine quartz in the silt fraction was above 10 and very high value, and suggested the influence of eolian dust brought from the Precambrian area in the southern part of China on the parent materials in this soil during MIS2. In two Dark Red soils, Sonai (SON) and South-meadow (MIN) soil, the ESR-signal intensities of silt sized fine quartz in the A and B horizon were also very high and suggested the eolian dust from Precambrian area in the southern part of China. On the other hand, the ESR-signal intensities of fine quartz in the A and B horizons in a Red-yellow soil, Urabu (URA) soil were slightly low and the parent materials in this soil were the mixture of eolian dust from the Precambrian area in the southern part in China and autochthonous Tertiary bedrock. The parent materials in four reddish soils developed on the Tertiary bedrock in Yonaguni island were derived from the eolian dust brought from the Precambrian area in southern part of China during MIS2, Last glacial Maximum. While a small amount of the autochthonous Tertiary materials were slightly mixed to the parent materials in these soils. This result obtained from the ESR-signal intensities of fine quartz were harmonized with the clay mineral composition in these soils.

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Rehabilitation of tropical rainforest on degraded forestland requires sufficient knowledge of soils. However, in Malaysia, the empirical data of soil properties on degraded forestland under rehabilitation are still lacking, In order to get fundamental information for evaluating the performance of rehabilitation program under various planting techniques on such degraded forestland, firstly, soil profiles of the planted forest of degraded forestland and adjacent natural forest need to be investigated. This study was conducted to elucidate the soil morphology, mineralogical and physico-chemical properties of degraded forestland under rehabilitation in two major forest types at Bukit Kinta and Chikus forest reserves in Perak, Peninsular Malaysia, representing hill and lowland dipterocarp forests, respectively. Shorea leprosula and Shorea parvifolia were planted at both sites. At the Bukit Kinta site, three soil profiles were prepared at two planted forests and one natural forest of hill-dipterocarp. At Chikus site, three soil profiles were examined under one planted forest, one mixed plantation with Acacia mangium and one natural forest of lowland dipterocarp. The soils at Bukit Kinta were derived from granite and showed clayey texture, while those in the Chikus showed relatively sandy texture resulting from their sandy parent materials and fluvial deposits. Soil profiles at Bukit Kinta were relatively uniform, while those in the Chikus site were greatly fluctuated upon micro-topography including water stagnant condition during rainy season. Based on the mineralogical and charge characteristics, the soils in the planted forests and natural forest in both study sites were strongly weathered but had not yet reached the ultimately weathered phase. The clay mineral composition was dominated by kaolin minerals (Bukit Kinta) and gibbsite (Chikus), with almost devoid of 2:1 type clay mineral, while both Al and Fe oxides were low. The soils in both sites were acidic due to the presence of a high amount of exchangeable Al which concomitantly increased the level of Al saturation. The variable negative charges derived from organic matter can potentially play an important role in cation retention, but its contribution under field conditions on the study sites were relatively small due to strongly acidic conditions. The plantation of the trees for rehabilitation (12 and 14-year old) could not sufficiently restore the soil organic matter to the same level as that of the natural forest caused by disturbance preceding the project. It can be concluded that the fertility status of the soils at planted forests were generally lower as compared to the natural forest in both study sites.

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男鹿半島入道崎付近に分布する新第三紀岩上に発達した2地点の細粒質褐色森林土の母材におけるアジア大陸北部由来風成塵の影響を調べるために,微細石英中の酸素空格子量から求められるESR信号強度と粘土鉱物組成を分析した。結果は次の通りである。安全寺および戸賀の2地点の土壌における電子スピン共鳴(ESR)信号強度は10以上という高い値を示した。このことから,2地点におけるA〜Bw層の土壌母材へ先カンブリア紀岩由来の多量の風成塵が影響を及ぼしておりさらに,これらの風成塵は,MIS2(2万4千年〜1万1千年前)に,冬季季節風によって運ばれてものであるとみられた。一方で,これらの土壌母材へ火山性岩もまたわずかに影響を及ぼしており,アカホヤなどの少量のテフラの影響もみられた。さらに,安全寺土壌の赤色化した2BC層における母材はアジア大陸北部の先カンブリア紀岩由来の風成塵の影響を強く受けている一方で,現地性火山岩の影響もやや強く受けていた。

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能登半島猿山岬の第三紀および第四紀岩上に発達した細粒質土壌の母材におけるアジア大陸北部由来風成塵の影響を調べるために,微細石英中の酸素空格子量から求められるESR信号強度と粘土鉱物組成を分析した。結果は次の通りである。猿山岬土壌におけるESR信号強度の10以上という高い値は、以下のことを示した。猿山岬土壌における母材へ先カンブリア紀岩由来の多量の風成塵が影響を及ぼし,これらの風成塵は,アジア大陸の内陸が非常に乾燥した最終氷期・MS2(2万4千年〜1万1千年前)に,冬季季節風によって運ばれたと考えられた。しかしながら,猿山岬土壌の母材へ現地性物質もまたわずかに影響を及ぼしていた。さらに,K-AhやATなど少量のテフラの影響もみられた。

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能登半島宝立山山頂付近の第三紀デサイト質火砕岩上に生成している細粒質褐色森林土壌の母材への風成塵の影響を調べるために,微細石英中の粘土鉱物組成と酸素空格子量を反映するESR信号強度について検討した。その結果は以下のように要約される。この土壌中の微細石英の電子スピン共鳴(ESR)信号強度10以上の高い数値は,次のことを示唆していた。アジア大陸北部の先カンブリア界由来の風成塵がこの土壌の母材に強く影響を及ぼしており,この風成塵はアジア大陸北部の乾燥した時期の海洋同位体ステージ2(MIS2)の最終氷期最盛期にアジア大陸北部先カンブリア界から北西季節風によってもたらされたものであった。一方,現地性の第三紀岩もまたこの土壌中の母材上に少なからず影響を及ぼしていた。さらに,この土壌中には少量のA-Tnなどのテフラの混入の影響もまた示唆された。

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