The Shimagare phenomenon which is called ‘wave-regeneration’ in the United States, is characterized some crescent-shaped bands consisted of a mature forest, dead trees and young seedlings. Many ecologists, dendrologists, geographers and others have already examined the phenomenon from their own viewpoints. The purpose of this paper is to reconsider the distribution and the locational condition of this phenomenon in Japan. As a result of aerial photograph analysis, some areas have newly been added to the distribution area of the Shimagare phenomenon. It becomes clear that the reexamined distribution area fundamentally coincides with the geographical distribution area of Abies mariesii and A. veitchii. It is noticeable that the scale of the Shimagare strip, crescent-shaped band, is smaller in Tohoku district (north-eastern Japan) than in central Japan. It can be said that the reasons why the Shimagare strip is smaller in Tohoku district are as follows: 1) the mountain areas are consitituted of small geomorphic surfaces, 2) the sub-alpine forests are dominated by A. mariesii, stronger species, 3) the Shimagare does not appear on southfacing slopes more influenced by sunshine effects. The Shimagare strips mostly appear at upper sub-alpine forest one near the top of the mountains, and also on south-facing gentle slopes except in Tohoku district. These facts point out that the Shimagare strips are distributed where pure fir forests are liable to be formed and to be damaged by the desiccation. On the other hand, the arrangement of the Shimagare strips characterized by dead trees show more concentrated direction. Comparing this direction with the direction of wind-shaped trees, both are not necessarily the same with each region. For example, both directions almost agree on Mt. Hakkoda and Mt. Higashi-azuma in Tohoku district, but not Mt. Nantai in Kanto district. These facts closely correspond to the pattern of seasonal variation of wind direction obtained by instrumental observation. For example, meteorogical records of the Mt. Nantai show the considerable frequency of southerly wind corresponding to the direction of arrangement or movement of the Shimagare strips during warm season, but not during cold season. With these facts, prevailing wind during warm season is considered to act as an important factor for the movement of Shimagare strips. And, if the direction of strong wind coincides with prevailing wind direction during warm season, the Shimagare strips will be moved faster.
Boso Peninsula, Central Japan was studied topographically and geologically. The result is as follows: (1) The base of the Iioka upland is constituted by the Inubo Group which is divided into three formations; the Na-arai, Iioka and Toyosato Formations in ascending order. The Inubo Group is overlain by the Katori Formation with slight unconformity. The Katori Formation is conformably overlain by the newly named Byobugaura clay. The Kanto Loam overlies the Byobugaura clay with unconformity, and is covered with sand hills (dunes) in some places (Fig. 1). (2) The geomorphic surface of the Iioka upland can be divided into seven forms, namely, tableland, shallow-depression, gentle-slope, steep-cliff, extended-valley, extended-channel and valley bottom. Among them, a new geomorphological term: extended-channel which forms between the extended-valley and valley bottom is proposed (Figs. 3, 4 & 7). (3) The stage of the drainage system (valley topography) in the Iioka upland is younger than that in the Shimosa upland. Many tributary streams of the Takada river show mainly north trend (Figs. 1 & 3). These branches go down to the gently-sloping area. (4) The littoral deposit is observed in the valley bottom. (5) The feature by summit level map seems to be nearly the same with that of the base of the Katori Formation. This means the evidence of basal movement since the end of the last glacial epoch. (6) The valley-in-valley is indicated in the longitudinal profile of the main river bed. A coast line in 6000 years ago can be traced from the data of erosional speed of 30m/60 years (KAWASAKI, 1954) and at that time the sea-level was about 4 meters higher than that of the present time from the equation of longitudinal profile of the old river (Fig. 9). (7) The height of the Iioka upland at the time of regression of the last glacial epoch was exactly lower than that of the present time. A value of ascending velocity of sea-level after the last glacial epoch is estimated 1-1.3cm/year. As the upheaval velocity of the Iioka upland was smaller than that of sea-level after the last glacial epoch, the “transgression”was taken place on the Iioka upland area. The sand hills (dunes) were formed at that time. After the last transgression this upheaval was discontinuous in the Iioka upland.
Man, from ancient times, has been acting as an agency to change the face of the earth. Man has built civilization by utilizing land and natural resources. In other words, various civilizations have been built at the expense of natural environment. There are many evidents of the destruction of soils, forests, grasslands and streams as a result of inadequate land use, and of the consequent declines of some civilizations. As the population of the world increased, man was forced to find more lands to support the multiplied members. Thus, people started to spread over the face of the earth. Conquerors, pioneers, immigrantswhatever you call them-they all contributed to the further changes in natural envionm ent by exploiting the newly acquired lands. The New World, where a balance between climate, soil, vegetation and the native life had been reached before settlement by Europ eans, went through drastic changes. Soils on the continents of America and Australia, for example, have deteriorated at an unprecedented rate within a matter of a few hundred years. In recent years, the problem of desertification of lands in arid, semi-arid and even moderately humid regions of the world has become exceedingly serious. Millions of people living on unproductive lands are starving to death. The attention has been brought up to various international institutions and the United Nations Organization, for one, has been actively working on the matter. However, the most important thing is for all the people to realize the role of human activity in the desertification process-in effect to think why resource management is leading to resource deterioration, if not destruction. It is also a known fact that the people living under harsh climatic conditions tend to regard natural hazards as something which they are doomed to live with, something entirely beyond their control. Therefore, it is essential to convince them, particularly those who engage in agricultural and pastral activities, to face, instead of shutting their eyes to, the problem and to learn how to cope with it. This paper tries to indicate the fact that human activity is responsible to a great deal, if not entirely, for the destruction of natural environment. A semi-arid region in Australia was selected as the study area, as the country has exhibited some of the most serious human impacts on the deterioration of land. The study is mainly concerned with soil salting and erosion, seeing these as an index of the relationships between climate, water balances and biotic forms on one side and human land use systems on the other. The Glenelg Catchment Project is a major soil conservation scheme taken place in far Western Victoria. It is a project in which landholders co -operated with the Soil Conservation Authority to carry out soil conservation and erosion control measures to protect the productive capacity of their land, the beauty of the landscape, and to prevent the siltation of the Glenelg River and its major tributary, the Wannon. The co-operative approach on which the scheme is based has spread, from 1962 to the present, involving some 5, 200 square kilometers and 1, 350 landholders. The case study shows why the project was necessary, how it came about and what has been achieved…and the problems yet remain to be solved.