On the Kawachi plain (the southern area of Osaka prefecture) primitive agricultural sites ranging from early to middle Yayoi periods (200B.C.-100 A.D. ) were buried about 4 m below the ground level. The environmental reconstruction was made to understand man-and-land relationships during this period. The lobate delta on which Yayoiman lived spread over the southern part of Kawachi plain during the early and middle Yayoi periods. The micro-relief of lobate delta was characterized by two land-form types, i.e. dry highland and marshy lowland. The dry highland, was composed of sand and gravel, stretch along the many tributaries of Yamato River. The marshy lowland, rich in humic soil, was scattered between the dry highlands. The marshy lowland was utilized as the rice field. The surrounding vegetation of the residential highland was characterized by grassland, in which the leading elements were Gramineae, Artemisia, Compositae, Cyperaceae, Persicaria, Polypodiaceae, Lycopodiaceae. The sea-1evel was 2-3 m lower than the present level. In the latest middle Yayoi period, the great flood occured and residential area was submerged. The man had to leave their highland place and migrated into a much higher district. After this catastrophic submergence, the residential area of the Kawachi plain was covered by the black humus clay deposited under a lagoonal environment. The pollen and spores of water plants such as Trapa, Nuphar, Urticularia, and Ceratopteris were found from this humus clay. This submergence of the Kawachi plain might have been caused by the rising of the sea level. The lagoonal environment continued throughout the late Yayoi period. At the beginning of the Kofun period, the original level of the Kawachi plain lowered and the stradline of the lagoon regressed. After this period the flood plain spread over the southern part of the Kawachi plain. Man readvanced into the flood plain which was covered by the natural levee deposit composed of silt and sand. In the northern part of the Kawachi plain, some relicts of lagoon still existed in the Edo period.

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An investigation was conducted into the distribution of wild boars in the southeastern area of Hiroshima Prefecture. In the prefecture, we can see a striking outflow of population from the mountainous areas to the urban areas. The damage of wild animals such as wild boars or monkeys has become one of the causes that brought about depopulation, and in the southeastern area, it has been very severe. These situations have been caused by a breakdown of the ecological balance between men and wild animals, and an approach from the geographical field in which man and man's environment is the main theme is expected to be necessary. Such approach is few and far between in the Japanese geographical field, the author has conducted an investigation into these situations, in the concrete, distributional maps of the wild boars were prepared and investigations into the damage of wild boars and backgrounds of fluctuations of wild boars were conducted. Futhermore, the author hopes that this research will become foundations to project on synthetic management of forests in due consideration of wild animal's conservation. Generally, the wild boar's distribution is regulated by a topographical condition and a vegetation, but in Japan where we have high population density and extensive forest-use we must not ignore the direct and indirect influence by men. In the investigation of the southeastern area in Hiroshima Prefecture, the author points out two types of the distribution as follows; 1) Before the World War II there was a fair distribution of wild boars in the state forest, but there after they decreased in number. 2) Before the World War II, wild boars did not inhabit in the privately owned forest, but from that onwards they became to have habitats there and increased in number. After about 1970, they began to decrease. Firstly, the author refered to the topographical condition in analyzing these distributions, but in this area there was no significance. Next, consideration was given to the vegetation, with the result that it was the important factor influencing the distribution. The difference In management between the state forest and the privately owned forest has produced the difference in the distribution, namely changes in the forest-use have influenced the vegetation and regulated the distribution of wild boars. Under these situations, depopulation has broken out in the latter. The increase of the damage of wild boars has stimulated the elimination's system and with the introduction of the wireless and the superior hound, wild boars have begun to decrease. In short, the distribution of wild boars is influenced largely by man. In future, the effective management of forests in due consideration of wild animal's conservation has to be projected.

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The purpose of the present paper is to come to a more general understanding of the urban structure of Hiroshima City by investigating urban factorial ecology from the viewpoints of both residential area and economic space. The urban area of Hiroshima City, with a population of 852, 607 in 1975, is divided into 39 areal units by using the aggregated census tracts and the former municipalities which were recently amalgamated. As shown in Tabs. 1 and 2 the writers carefully selected about 30 input variables including the changing ratio data in both analyses. The results of factor and cluster analyses using these input variables are summarized as follows: 1 ) Within the five factors which were extracted by factor anaysis (principal axis method and Varimax rotation) of residential area characteristics and explained 83.6 per cent of total variance, only three factors were clearly interpreted. These were urbanisation, urbanity and economic-occupational factors The third one, named economic-occupational factor, would correspond to the dimension of socio-economic status which are generally labelled by many studies. The factor structure analysed Is considerably different from the result of the previous investigation in which 55 smaller areal units (census tracts) within the former city boundary excluding suburban areas were used. It may be based on the difference of areal boundary and areal units, though the input variables also were not the same. 2 ) The standardized factor scores of each of these three factors are distributed as shown in Figs. 2, 3 and 4. The urbanisation factor has high values in the suburban area with strongly advancing urbanisation, whereas it has low values in the central area with obvious decrease of inhabitants and in the rural area where the waves of urbanisation seem not to have arrived. Both the distributions of urbanity and economic-occupational factors are close to a concentric pattern. But the latter factor has the two areas of highest score values in the built-up area. 3 ) Though seven factors extracted from the factor analysis of economic-space characteristics explain 82.3 per cent of total variance, only four main factors are clearly discerned. These are retail and eating-drinking, rural (rurality), industrial activity and manufacturing dominant factors. The score distribution of the retail and eating-drinking factor shows a concentric pattern with remarkably high values in the CBD and may be similar to the distribution of land values. It is noticeable, however, that commercial areas in the periphery of the central area which were formerly developed as sub-centres, tend to be stagnant or declining in the recent retail turnovers as shown in Fig. 10. Although the rural factor is also distributed in the form of a concentric pattern, its pattern is quite contrary to that of the first factor. On the other hand, industrial activity and manufacturing dominant factors show irregular patterns. While the values of the former are high in the areas with many establishments com-pared to inhabitants, those of the latter show the highest values in the coastal industrial zone and relatively high values in the areas along Routes 2 and 54. 4 ) As anticipated from the distribution pattern of factor scores for each factor mentioned above, the urbanisation factor in residential areal characteristics and the manufacturing dominant factor in economic space characteristics are scarcely correlated with other factors, so that each factor appears to make an independent dimension. Moreover, new groups can be classified from the results of Tab. 6 and Fig. 12, which were depicted by combining all five groups classified by cluster analysis of Ward's method; CBD (A), marginal area of CBD (B), the area specializing in administrative functions and with a complex of large apartment houses (B'), manufacturing area within the built-up area (C), residential area in the marginal

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