近年,わが国におけるアユ養殖業の発展は,一方において養殖地域の再編成を伴いながら進行している.そこで本稿では,全国最大の産地,那賀川平野のアユ養殖地域を事例に,地域分化の形でみられる再編成の実態とその要因を総合的視野から検討した.結果を要約すると以下のとおりである.
那賀川平野におけるアユ養殖地域は, 1964年以降産地化を進め,共撰共販体制下で生産性を飛躍的に高めて,全国最大の産地に発展してきた.しかし,この発展は産地全体に一律にはみられず,自然的・社会的条件の違いに基づいて,地区ごとに地域差が生じた.すなわち,那賀川平野のアユ養殖業は,産地形成の当初段階から,地下水が豊富な旧河道の有無に基づく左右両岸での経営形態の地域差を生じていた.その後,主産地形成事業に伴う支部制共撰共販体制の導入は,経営形態の地域差をより拡大化・固定化すると同時に,左右両岸での流通組織の地域差も顕在化させていった.第一次石油危機以降,生産費の高騰とアユ卸売価格の低下で,経営規模の内面的拡充による生産費の軽減がより重要視されるに至った.その結果,基本的に養殖業を支えている水条件の優劣が,経営の収益性を通して黒字・赤字地域という2つの地域分化を促すことになった.
以上に述べた,経営形態・流通組織・収益性を指標にして那賀川平野におけるアユ養殖地域を区分すると,左岸上・中・下流部,右岸上・中・下流部の6地区に類型化できる.なお,地域分化を規定する主たる要因としては,水条件(主要因)と流通組織(副次的要因)の2点を指摘することができる.

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This paper discusses recent studies since 1975 on the tectonic geomorphology of New Zealand, acountry which is well-known for work on this subject. The regional character of the tectonic landforms is controlled mainly by the tectonic setting of New Zealand at the boundary between the Australian (Indian) Plate to the west and the Pacific Plate to the east, with opposed subduction zones at the northeast and southwest margins and a complex zone of shear deformation linking the two. The Taupo Volcanic Zone in North Island is a volcanic arc and marginal basin characterised by volcanism and crustal extension.
Active faults and deformed marine and fluvial terraces are prominent tectonic landforms. Detailed research on the Alpine Fault are being supplemented by intensive works on active reverse faults. In South Island this includes trenching studies. The characteristics of the deformed topography and trench logs across the Dunstan Fault and Pisa Fault in the Otago area demonstrate the close similarity between reverse faulting here and many active reverse faults in Japan. The deformation of fluvial terraces and the height of postglacial transgressive deposits and marine terraces indicate a very high uplift rate in the Southern Alpes east of the Alpine Fault which is ascribed to vertical drag along the Alpine Fault due to the plate convergence.
Marine terrace studies, especially in North Island and some parts of South Island have made much progress. In North Island, the last interglacial terrace reaches a maximum height of 300m and the postglacial terrace a maximum of 27m. The deformation pattern shows regional differences. In North Island, landward tilting away from the Hikurangi Trench is observed on the eastern coast. Folding with short wavelength and small-scale block faulting dominate the central to southeast coast and the south coast. Downtilting towards the sea continued in the Taranaki area during the middle to late Quaternary. Holocene marine terraces can be used as reference surface for the reconstruction of paleoseismicity. Fourteen tectonic regions are identified on the east coast of North Island on the basis of the number of subdivided Holocene marine terraces and their radiocarbon ages. Some of offshore seismogenic faults are inferred from submarine landforms and records of obtained seismic profiling. In South Island, discussion has focused on the recognition of very high terrace remnants and on age estimation of terraces which have no datable materials and key beds for correlation.
Tectonic landforms have been used as references for compiling a Quaternary uplift map. The maximum uplift rate of 17mm/yr is located on the east side of the Alpine Fault, South Island. The highest uplift rate in North Island is 4mm/yr north of Gisborne and Turakirae Head near Wellington and was derived from Holocene marine terrace data. It is, however, still difficult to establish a temporal sequence for uplift rates because of insufficient age control.

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The beech (Fagus crenata) is a, dominant tree species of the broad-leaved deciduous forest in cool temperate regions of Japan. The northernmost area of its distribution is situated in the Kuromatsunai Lowland in the northern part of the Oshima Peninsula. This paper discusses the distribution of forest vegetation in relation to micro-environmental conditions in the Utasai National Forest, which is thelargest primeval forest in this area that includes beech stands.
In order to observe the relationships between the distribution of forest vegetation and edaphic conditions, detailed-scale landform units were established on the basis of the morphology, component materials, and stability of the land surface. For each landform unit, soil type was determined in the field and soil water content was measured in the laboratory. The forest vegetation was classified based upon the dominant species of the canopy layer, and the correlation between the distribution of the community types and edaphic conditions was examined for each landform unit.
The results obtained by the present investigation can be summarized as follows:
1. The land surface, the soil profiles, and the forest vegetation were classified into 14 landform units, five soil types including one subtype, and five community types, respectively.
2. The distribution of the five community types is related to soil moisture conditions. They are arranged in the following order, from dry to wet habitats: the Fagus crenata type which dominates on landform units with the soil type BC-BD, the Quercus mongolica var. grosseserrata type on BD-BE, the Tilia japonica type and the Acer mono type on BE-BF, and the, Ulmus davidiana var. japonica type on BF.
3. A forest stand with no beeches is found on the terrace surface I. This clear-cut segregation has presumably resulted from soil drainage conditions.

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