Though the flora of Himalayas has attracted the attention of a number of researchers, the region is still largely unexplored ecologically. In this paper the author studied the zonatioii of vegetation in different successional stages in east Nepal, and the climax zones were compared with that of East Asia. Altitudinal zonation of climax vegetation in east Nepal Altitudinal zones of vegetation in east Nepal were stated based on the investigation during the field trip in 1971 and 1977 (Fig. 1). The following 5 forest zones were recognized in climax state from lower to higher altitude (Fig. 2). 1) The Shorea zone (below 1000 m) This is the zone of subtropical Shorea forests. Though the forests are most extensive in the southern foothills of Himalayas, they sometimes extend into the mountaineous areas along the big valley system such as Arun and Tamur. Shorea robusta is a leading dominant species in the forests of this zone, but besides this there are several other types of forest dominated by e.g. Adina, Dalbergia, Lagerstroemia, Albizzia, Bombax, etc. 2) The Schima-Castanopsis zone (1000-1900 m) This is the zone of warm temperate forests dominated by Schima wallichii and Castanopsis spp. In the lower altitude of this zone the forests are dominated by Schima and Castanopsis indica with scattered trees of Albizzia, while in the higher altitude the Schima-Castanopsis forests are largely replaced by C. tribuloides and/or C. hystrix forests. On the rocky scree slopes the dominant species is replaced by Quercus lanuginosa. The Pinus roxburghii forest is the most extensive type of forest in west Nepal, while in east Nepal this forest is quite restricted to the south-facing steep slope only. 3) The Quercus zone (1900-2500 m) This is the zone of temperate lauro-fagaceous forests. In the easternmost parts of Nepal these forests are dominated by Quercus lamellosa and Q. lineata and are usually mixed with Litsea spp., Machilus spp., and Acer campbellii. In easternmost parts of Nepal Acer campbellii, which usually dominates the upper forest zone, commonly occurred in this Quercus zone. 4) The Acer zone (2500-3000 m) This is the zone of deciduous broad-leaved trees, such as Acer, Magnolia, and Sorbus. In some parts of this zone there are also coniferous forests dominated by Tsuga dumosa. One of the peculiar features of vegetation in this cool temperate zone of Nepal Himalaya is the presence of the evergreen broad-leaved forests, the Lithocarpus pachyphylla forest and the Quercus semecarpifolia forest. 5) The Abies zone (3000-3800 m) This is the uppermost forest zone bounded on the upper end by the forest limit (ca. 3800 m) and corresponds to the subarctic zone. Betula utilis and Rhododendron spp. are the most commonly accompanying species in this zone. Altitudinal distribution of species in different successional stages The above-mentioned zones of vegetation in climax state might be modified by various factors, among which the most strong and extensive disturbing factor for natural vegetation is the anthropogenic ones in east Nepal, e.g. farming, shifting cultivation, grazing by catties, etc. The extensive areas of secondary vegetation could be observed especially in the region lower than an altitude of 2000 m. As a basic information for the comparison of vegetational zonation in various successional stages the altitudinal distribution of species has been worked out separately for the pioneer and grassland herbs, the pioneer shrubs, the pioneer trees, and the climax trees (Fig. 3). In Fig. 3 certain marked differences in the distributional behaviour of the species can be distinguished in each successional stages. In general species distribution overlaps one another in a greater or lesser degree according to their successional status. In the pioneer and grassland herbs the distribution range of each species was quite large and sometimes reached to 2000 or 3000m of altitudinal range. And

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A residual soil derived from green schist of Nagatoro metamorphic zone, is distributed on the mountaineous area nearby Yahatahama, Ehime prefecture. Clay mineralogical investigations are made for a representative soil profile in this region, in order to obtain informations about the weathering and formation of clay minerals in the soil of this type. The soil samples are taken from the different horizons (B, C, R horizons), and the mineralogical compositions of the different size fractions are studied mainly with x-ray and chemical analyses. The results obtained are as follows : (1) The parent rock consists of muscovite-celadonite, hornblendes schists in which there are small lens-shaped quartzite inclusions, and of quartsitic veins which penetrated obliquely through the schists. The schists have a strong fissility and surface of the flakes is yellowish brown in color, showing the vermiculization on this portion. (2) The parent material (C horizon, 20-80cm) is yellowish (2.5 YR 6/4) and contains marked amounts of fresh to weathered green schist fragments. Mineralogical study of fine sand and silt fractions shows a presence of vermiculite, hornblendes, plagioclase and small amounts of di-subgroup mica and quartz. Beside these minerals, fairly high amounts of metahalloysite are found in the clay fraction, the clay content being 15% of the fine earth. (3) Soil in B horizon (5-20 cm) is light brown (7.5 YR 5/6), with 31% clay content, indicating much higher amounts of weathered materials are present in this horizon than in C horizon. The mineralogy of fine sand and silt fractions is almost similar to that of C horizon. In the clay fraction, however, remarkable amount of metahalloysite, vermiculite, and a small amount of hornblends are identified. The formation of vermiculite/chlorite regular inter stratified mineral is also suggested from X-ray analysis. (4) A schematic model is presented as a mineralogical weathering sequence of green schist (muscovite-hornblendes schist). The full weathering sequence so far arrived at from present study was : formation of vermiculite from muscovite (celadonite) and hornblendes, vermiculite/chlorite interstratified mineral from vermiculite, and metahalloysite from plagioclase, which are accompanied by the release and leaching of K+ and Mg++, the accumulation of iron oxides and the desilication throughout soil mass.

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Pedogenic studies were made on the Red-Yellow soils with ashen gray surface horizons which occur frequently in the upland and hilly regions of the Okinawa Island. 1) The soil studied have the thin A_0, over the dark gray (7.YR5/2) A_1, light gray (2.5Y 7/1) A_2g, and transitional A_3g horizons of loamy textures, over the yellow brown (7.5YR 6/5-6) fine textured B_<21>t-B_<23>t horizon. The A_2g and A_3g are mottled with orange colored speckles. The ashen gray A_2g often intrudes into the upper part of the Bt in the form of streaks along the cleavages. The ped-faces of the Bt are normally darkened with illuviated humus. (Photo. 1) 2) The properties of the soil, particularly the clay mineral composition and the lower activity (higher crystallinity) of free iron oxides, along with the physiographic and climatic environments, indicate that these soils are Red-Yellow soils formed under perhumid subtropical climate. 3) Although clay skins are nearly absent in the Bt, the plasma is unusually abundant in birefringent domains (Photo. 2). The clay content and the fine clay to total clay ratio have their maxima in the B_<22>t horizon (Fig. 2). We conclude that the Bt horizons are argillic, and that clay skins once formed have been incorporated into matrix due to a disturbance by swelling and shrinkage. 4) Ashen-gray color can not be produced by lessivage alone, though it reduces considerably the chroma of surface soils. Superposition of a weak podsolization was assumed from (a) strong acid reactions in the A_1 and A_2g (Table 1), (b) presence of a local maximum of organic matter in the B_<21>t (Fig. 1), (c) distinctly lower sesquioxides/clay ratio in the A horizons compared to the underlying Bt (Table 1), and (d) dominance of expansible vermiculite free of interlayer-Al in the A_2g as contrasted to strongly Al-interlayered vermiculite in the B_<22>t (Figs 4 and 5). 5) Morphological features of the A_2g and A_3g that have orange colored speckles with light gray parts spreading along conducting channels suggest the occurrence of a weak surface pseudogleyzation. The closely packed A_3g may be responsible for the separation between seasonally saturated upper horizons and continuously aerobic lower horizons. (Fig. 3). 6) Lessivage would have paved the way for podsolization by lowering the sesquioxide level, and also for seasonal saturation and consequent pseudogleyzaby promoting the formation of the impermeable A_3g horizon. It may be concluded therefore that the ashen gray surface horizons have been formed by the polygenic processes of lessivage, and podsolization and surface pseudogleyzation.

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