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This study examines vegetation succession and soil physico-chemical properties in the upper reaches of the O'Donell River, which have been affected by the seasonal lahar since the 1991 eruption of Mt. Pinatubo, central Luzon, the Philippines. Field surveys and physico-chemical analyses of lahar deposits and soil were carried out in areas including the living zone of the Aeta to understand the land recovery process along with land management practiced by the Aeta. Seedlings of Ararong (Trema orientalis) associated with root nodule bacteria are widely distributed on the lower lahar terraces and it was pointed out that Ararong is a pioneer plant. It is also the dominant species of tree and shrub layers on higher lahar terraces, and has a tendency to reduce its height in response to increases in coverage of herbs such as Talahib, Magkakamote, and Bureok. Vegetation succession was divided into the following stages (I–IV) based on an interpretation of the development of the geomorphological surface and a vegetation survey. The former surface soil of the 1991 pre-eruption was tentatively defined as the goal of land recovery and was classified as Stage V. A grain-size analysis of lahar deposits and soils in φ scale was carried out by the dry sieving method. Chemical properties of lahar deposits and soils were examined by analyzing total carbon (T-C), total nitrogen (T-N), total phosphorus content (T-P), C/N ratio, pH (H2O), cation exchange capacity (CEC), base saturation (BS), and total elemental composition. Lower terrace of post-eruption lahar deposits with no vegetation (Stage I) and lower terrace of lahar with Ararong seedlings or herbs (Talahib, Bureok) had low T-C contents 0.2–0.58 g kg-1, and no significant differences were recognized between the two stages. The higher terrace of lahars with Ararong of 2–5 m height and herb coverage (Stage III) and ridge area affected by the 1991 pyroclastic flow and/or fall deposits, currently used as fields with shifting cultivation (Stage IV), had an increased T-C content of from 0.37 to 8.9 g kg-1 in response to the increased density of the vegetation canopy and number of vegetation species, which showed an exponential increase towards Stage V (21 g kg-1). The T-N content showed a slight tendency of nitrogen accumulation occupied by Ararong and rhizobial nitrogen fixation. As far as we examined soil pH (H2O), T-N, CEC, and BS, the soil fertility of the shifting cultivated field and the secondary forest (stage III, IV) in the upper reaches of the O'Donell River is equivalent to that of the fields on plains of the Bambang and Pasig-Potrero rivers. Nitrogen fixation by root nodule bacteria of Ararong, and available phosphorus supply originating from apatite in the lahar deposits are both accelerated by the elution of organic acids from herbs such as Talahib. Potassium supply from the weathering of plagioclase and biotite, the major minerals of lahar deposits, is also the basic process responsible for land recovery on the upper slope of Mt. Pinatubo. Based on analytical data from this study, it is found that the activity of the Aeta people of burning down secondary forests of Ararong to open small areas of arable land is not a regulating factor against land restoration. The soil-forming process, which is closely related to vegetation management from the activities of local people, may help us to understand the ongoing sustainable development in the upper reaches of the O'Donell River.

Records of short-term environmental changes caused by urbanization and industrialization are expected to be preserved in lake sediments. Besides, a consistent, high-resolution baseline record is required to interpret extreme influences of human impact such as heavy metal pollution and eutrophication. In this study, the numerical dates of the core samples taken from Lake Teganuma are determined using the 210Pb and 137Cs dating method. Concentrations of heavy metals are obtained for centrifuged water samples with wet core samples, and for HCl and acetic ammonium extracts with oven-dried core samples, to clarify the existing state and the mobility of metals. Total carbon content, total nitrogen content, and C/N ratio are also obtained for ovendried core samples to analyze the influence of human impact on water deterioration of Lake Teganuma. According to the analytical results for total carbon, nitrogen, and C/N ratio, the eutrophication in Lake Teganuma started around 1946 and shifted further to a critical condition in the late 1960's. Zn and Cu pollution began around 1955, while serious Cr pollution occurred around 1963. These responsible factors for the water environmental changes in Lake Teganuma represent stresses of population increase and drainage closure due to reclamation.

Sclerotium grains, the resting structure of an ectomycorrhizal fungus, Cenococcum graniforme (currently, Cenococcum geophilum), are black and spherical, 1-2 mm in diameter have a characteristic hollow structure, and can be easily found in forest soils. The maximum content of sclerotium grains in surface soils of Japanese Andosols is 3.40 g kg-1, which suggests that the contribution of sclerotium grains to forest soils cannot be ignored as one of the soil organic components. This paper introduces the interests of the biological strategies of Cenococcum geophilum and sclerotium grains by reviewing the findings of advanced studies on micromorphological features, chemical composition, and microbial communities of sclerotium grains.Instruments such as scanning electron microscope (SEM) and energy dispersion X-ray fluorescence micro-analyzer (EDX), electron probe micro-analyzer of wave dispersion type (EPMA) and 27Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) were used to obtain the characteristics of sclerotium grains. A basic finding was that C is the major element in sclerotium grains associated with a relatively large concentration of octahedral Al, which suggests an Al-humus complex. The mean concentrations of major elements in sclerotium grains are quantitatively defined as C (47.6%), O (30.2%), H (3.32%), Al (1.4%), N (0.78%). Carbon in sclerotium grains took the form of large amounts of 0-alkyl C and was also associated with aromatic C and methyl C, which strongly showed a characteristic biological origin and completely different spectral feature to humic acids from an allophonic Andosol. AMS 14C age values obtained for sclerotium grains in surface soils of Japanese forest soils were from modern to 1800 yr BP, which proves its stability and long life as an Al-humus complex. Transmission Electron Microscope (TEM) and EDX techniques revealed the micromorphological features of the Al-oxyhydroxide polymorphs found in sclerotium grains. It is assumed that a biochemical process responsible for host fungi induced Al saturation and precipitation under acidic conditions to form Boemite inside the grain. Studies on microbial communities elucidated the predominance of specific species such as Sphingomonas sp.From a further investigation on the distributions of sclerotium grains in profiles of German Podsols, Braunfaherde and Brown Podsols, it is concluded that development of sclerotium grains was not always regulated by low pH but by the content of exchangeable Al and the status of Al in the soil, regardless of soil type. The sclerotium grain was likely to be formed in soils with high ratios (>0.6) of organic bonding Al (Alp) to amorphous Al (Alo), and with high contents of exchangeable Al (Al3+) (> 0.54 g kg-1).The Al accumulation in sclerotium grains and the close relationship between sclerotium grain density and the status of active Al in soils suggest the symbiotic function of Cenococcum geophilum with root by reducing the toxicity of Al under low pH in rhizosphere. Sclerotium grain may also serve as a shelter for microorganisms and preserve their diversity under severe environmental conditions. Although the findings we have are still very limited, the goal of the study is to understand further implications of sclerotium formation in a soil ecosystem, which may help us to learn what strategy is necessary for biota to survive a catastrophe.

The use of humic acid green fraction (Pg) as a paleoenvironmental indicator still requires integrated case studies applied to tephra and loess soil sequences (Watanabe and Kado, 2000; Watanabe et al., 2001a), as well as biochemical studies on humic acid Pg (Watanabe et al., 2001b). The stability and the chemical transformation of humic acid Pg should be elucidated by investigating paleosols and terrestrial deposits.This study aims to clarify the properties of humic acid green fraction Pg in the Shimosueyoshi buried layer (SB layer), the buried humic soil originating from tephra supplies of Hakone Caldera, corresponding to Marine oxygen isotope stage 5e. Pg absorption strength (Pg abs), total carbon content (TC), carbon content of extracted humic acid (CHA), pH (NaF) value, major element compositions, and phytolith analyses, together with selective dissolution of Fe compounds, and color measurement according to CIE color system were conducted. The obtained results were : 1) Clear Pg absorption bands at around 450, 570, and 615 nm were detected from all the humic acid of paleosols, corresponding to > 100 ka, located at Oiso Hill, central Japan. The fluctuation of Pg abs of humic acid in the investigated profile showed a significant increase in the SB layer (ca. 130 ka), equivalent to the early stage of MIOS 5e.2) According to the measurement error of Pg abs determined through the profile, the significant level of Pg abs in this study is confirmed to be much lower than that of Pg abs in previous studies carried on younger tephra soil sequences. It is considered that humic acid Pg is transformed in paleosols over 100 ka.3) Although the relations among amorphous and crystalline iron hydroxides and Pg absorption strength were not clear in this profile, unlike the previous reports (Kawahigashi et al., 1999, Watanabe and Kobayashi, 2001), the SB layer was characterized by the existence of geothite-like iron hydroxides, suggesting a humid environment.

In order to examine the usefulness of thermal images in analysis of thermal belt formation, eleven nocturnal LANDSAT/ TM thermal images of the southern slope of Mt. Akagi at the northern edge of Kanto Plain in central Japan were analyzed. Nine images have the higher LST (land surface temperature) on the mid-slope, which is always accompanied with LST difference due to land cover difference (forest dominating the mid-slope and the higher part of the slope has surface temperature higher than other land use categories), but appears with LST inversion in only two images. Because only the LST inversion may reflect thermal belt, these two elements must be separated before the image is used in analysis of thermal belt formation. The two images with LST inversion were acquired under similar meteorological conditions which should be considered as one of the possible factors of thermal belt formation.

The authors have an interest in establishing a valuable method for obtaining reliable information on environmental changes in the past by examining humus properties of volcanic ash soils. In this study we investigated Pg absorption, the spectral characteristics of humic acids. Remarkable absorbances in alkaline humic acids at wavelength of 615, 570 and 450nm were named Pg absorption by Kumada et al. (1967). Kumada (1981) considered that Pg is a kind of green pigments derived from sclerotia and that Pg contains compounds similar to DHPQ the derivative of 4 : 9-hydroxyperylene-3 : 10-quinone. Though Pg is widely found in world soils and is suggested to be a reliable indicator to infer vegetational and climatic environments of the past, the mechanisms of Pg formation is not yet known well. The purpose of this study is to clarify the environmental factors regulating the distribution of Pg absorption strength in the field and to evaluate Pg absorption strength as an environmental indicator through the investigation of properites of Pg absorption strength in volcanic ash soils in Japan.In this study we investigated 21 sites in six volcanic areas, the Towada, Akagi, Nantai (Nikko) of Northeastern Japan and Ashitaka of Central Japan and the Daisen and Kirishima of Western Japan. Each soil were sampled from surface layers of uncultivated lands. Besides soil humus analyses, which are of organic carbon content, humus composition and spectral properties of humic acids, phytolith composition was investigated to examine the relationship between Pg absorption strength and vegetational environment at present. Warmth Index and Humidity Index, which are climatic indices proposed by Kira (1945), were also calculated for each sample site using climatic grid data compiled in the Digital Information on Japanese Land.There was no relation between Pg absorption strength and carbon content. On the other hand, PQ (percentage of humic acid to total humus) and RF (color intensity of humic acid) both show negative correlation with Pg absorption. These facts confirm that Pg absorption strength is regulated not by the amount of humus but by the quantity and quality of humic acid. Referring to the report of Sato (1974), we consider that brown fractions in humic acids called Pb fractions mask Pg absorption appeared in spectral curves of humic acids.As for climatic environment, Pg absorption strength has a negative correlation with Warmth Index (n=20, r=-0.55*). The relationship between Pg absorption and Humidity Index is not clear enough to remark. Furthermore, we estimated the yield of grasses from the density of grass phytolith in soils. We found a strong positive relation between Pg absorption strength and the yield of Bambusoideae Sasa (n=21, r= 0.81***), while a negative correlation with that of Miscanthus (n=21, r=-0.67***). From this study, we confirmed that the strength of Pg absorption is strongly regulated by the vegetation. Particularly Miscanthus acts to control down the strength of Pg absorption.We must notice that most of the investigated sites in this study range in cool temperate forests. The role of Pg absorption strength as an environmental indicator will be clearer at the time when we make further investigation in soils formed under warm temperate forests.

By a series of studies to clarify the humus characteristics of volcanic ash soils and soil forming environment, the influence of climate variation was recognized in the eastern foot area of Nantai Volcano, Nikko (Watanabe 1985, 1987). The purpose of this study is to obtain useful information for the reconstruction of global scaled environmental changes from spatial distribution of soil humus characteristics. Volcanic ash soils developed in the southern foot area of Akagi Volcano were examined as a case.The result is summarized as follows.1. Soils developed over southern foot area of Akagi Volcano show several types of soil profiles regulated by the thickness and rate of tephra deposits and geomorphic surfaces. On mountain slopes formed by pyroclastic flow, brownish volcanic ash bed are to be seen between surface and buried humus layer. Soils distributed on central cone lacustrine surface have thick and dark humus layer called “gleyed Kuroboku”. Soils with light humus layer develop on piedmont surface under the influence of artificial activity. The brownish volcanic ash bed mentioned above is difficult to distinguish from this layer.2. The chronological sequence of soil formation in the study area was considered on the basis of properties of soil parent materials and radiocarbon dates. Horizon I is the layer which continues to accept humus supply and humification under soil forming environment in the present. Fresh volcanic ash errupted from Asama and Haruna Volcano, about 200-1700 years ago are included in this layer. Horizon II correspondent to the brownish volcanic ash bed has accepted humus substances from the upper layer. Though the source volcano is unknown, this layer is assumed to be deposited about 4, 000 years ago. Horizon III, a buried humus layer intercepted from surface environment, started soil formation about 9, 000 years ago following to the erruption of Asama Itahana Yellowish Pumice (YP).3. The vertical distribution of humus characteristics (brightness of soil color, carbon content and humus composition) was classified into two types, which reflects the conditions of vegetation and groundwater level regulated by gemorphic surface.4. The spatial distribution patterns of humus characteristics such as carbon content and RF value of humic acid in each horizon show vertical zonality. The principal areas of humus accumulation in the age of horizon II and III formation were located in higher location than present, about 400m upward. Humic acid classified such as type A+, P+ +, have remarkable absorption spectra near 615, 570, 455nm which are regarded to be the features of soils formed under vegetations such as Fagus, Quercus mongolica and also under cool and wet condition in the study area. The appearance of these humic acid types in each horizon also tend to move its location upward by 300m in the age of horizon III formation.