SUMMARISED EXPLANATION OF THE MAPS

OUTLINE OF JAPANESE ARCHIPELAGO

1. Biogeography of the World

   To illustrate the biological features of the Japanese Archipelago in the biosphere of the world, maps of the biogeographical regions most commonly used are presented.

   Biogeographical regions are divisions of the world according to the characteristics of flora and fauna. Divisions of zoogeographical regions differ according to the kinds of animals but here the regions for mammals are used.

2. Japan and its surroundings

   The Japanese Archipelago consists of arcs parallel to the eastern border of the Asian Continent, and separated from it by the Japan Sea. The arcs consists of, from north to south, the Kuril Arc, the Honshu Arc, the Ryukyu Arc, and the Izu-Ogasawara Arc which runs southwards from the center of the Honshu Arc. The limits of Japan are 45°33'N at Etrofu Island, 20°25'N at Okinotorishima, 153°59'E at Minamitorishima, and 122°56'E at Yonakunishima, covering a latitudinal range of 25° and a longitudinal range of 31°.

   In the adjacent sea flow the Kuroshio Current, the largest current in the world, and the Oyashio Current, which has its origin in the Bering Sea and northern Okhotsk Sea.

3. Names of physical regions

   In this map are presented the names of important geographic units. The units are mountain ranges, ridges, highlands, plateaus, hills, plains, basins, table lands, peninsulas, and islands, and the names adopted here are those generally used for a long time.

4. Geologic provinces

   The Japanese Archipelago is a part of the arcs of the western border of the Pacific Ocean and many kinds of geological phenomena are active.

   Since the Paleozoic, the Japanese Archipelago has been subjected to many distrophisms, and those in the late Mesozoic and the Neo-tertiary had the most conspicuous influence on the present geological structure, and formed the undulated landscape.

5. Landform classification

   Japanese Archipelago is much undulated and three-fourths of the land is mountains, including volcanos and hills. Mountainous areas are disected into small valleys and the slopes are generally steep.

   There are plateaus and terraces in many parts of the land. Volcanic plateaus are found mostly in Hokkaido and Kyushu and they are called "Shirasu Plateaus" in southern Kyushu.

   Plains and basins are mostly small and scattered amoung mountainous areas and many of them were formed by sedimentation of sand and gravels.

6. Geology

   Geological maps are prepared by the survey of distribution of rocks and formations and their kinds and ages. By use of the maps, the process of the formation of the present geology and the history of the topography are inferred.

   Geology is closely related to the formation of topography, and influences the surface soils.

7. Soils

   Soils are formed by the overall actions of soil-forming factors such as rock materials, climate, vegetation, topography, and ground water over a long period of time and are subject to incessant changes.

   Soils is the habitat of a rich variety of fauna and flora, and is changed by the interaction with those fauna and flora.

8. Climate

   According to the classification of Koppen, Hokkaido has a subarctic pluvial climate and the other parts have a temperate pluvial climate. Climatically, Japan is grouped into three parts from north to south,i.e., 1) Hokkaido, 2) Honshu, Shikoku, and Kyushu, and 3) the Ryukyu and Bonin Islands. South of the Tsugaru Strait, located at about 40°N, the fauna changes discontinuously; the line of this discontinuation is called Blakiston's line. The climate differs greatly between the two parts separated by this line. The climate of the two sides of the Central Ridges running through Honshu is also different.

   The climate of Japan is not only variable by parts but the changes according to season are also conspicuous, resulting in a diversity of flora.

9. Land use

   Land use of Japan is very complicated, reflecting the natural conditions of the land. Most parts of the mountains, hills and volcanos are covered by forests, and the rest is used for grazing land and orchards. Flatlands which include plateaus, terraces and bottomlands are used for agriculture or as urban areas. Bottomlands are utilized as paddy fields except when urban areas develop.

   The pattern of land use reflects the present state of the natural environment and the land use map gives fundamental information on the present state of the land.

10. Population density

   Population density is an important index of human intervention in nature. The population density per square kilometer in Japan was 294 in 1976, being sixth largest in the World.

   The population dinsity of the flatland is much higher because three quarters of the land area of 380 thousand spuare kilometers is mountainous and not habitable.

   The population density of municipalities is higher in flatlands and urban areas, and lower on the mountainsides and in most parts of Hokkaido.

NATURAL ENVIRONMENT OF THE LAND

13. Actual vegetation

   The actural vegetation map represents the spatial distribution of vegetation actually growing. The difference in vegetation reflects the difference in the environment which includes temperature, precipitation, soil, topography, and human activities. On the other hand, vegetation influence environment.

14. Degree of human disturbance of vegetation

   The degree of environmental disturbance of the land was estimated through the species composition of plant communities, and can be used as an indix of the intactness of the natural environment of the land.

15. Potential natural vegetation

   Potential natural vegetation is the vegetation that is supposed to appear after all human intervention stops. Different from the original vegetation that grows before human intervention, it represents the capacity of the site to grow that kind of vagetation.

16. Alteration of surface ground

   Despite the importance of surface ground as a resource to support ecosystems, alteration of it has progressed without principle. Here is presented the time sequence of alteration of surface ground by taking the states of land use in the Kanto Region in 1945, 1960, and 1975, as examples. It is obvious that the alteration by the sequence of natural forest-planted forest-farmland-urban area, or paddy fields to urban areas is progressing.

17. Plant biomass and biomass production

   Plant biomass represents the total amount of living plant materials, and the biological production is the total amount of organic matter produced by the plant communities, both expressed as dry weight per unit ground area.

   They are the basic figures of the cycle of matter in ecosystems and serve as indices of the natural environment.

18. Important plant communities

   In the survey of the Designated Plant Communities of the Second National Survey on the Natural Environment, an investigation of plant communities scientifically important or worth protecting was made. 3,833 communities were reported from all over Japan. Here are presented the distribution of primeval forests or natural forests close to them, evergreen broadleaved forests, beech forests, and marshes as representing the important plant communities.

21. Distribution of large mammals

   Of the large and medium-sized mammals, which are feared to be decreasing, the distribution of nine species is presented. The species are: Macaca fuscata, Cervus nippon, Selenarctos thibetanus, Ursus arctos, Sus scrofa Vulpes vulpes, Nyctereutes procyonoides, Meles meles, and Capricornis crispus.

22. Numbers of mammalian species

   The number of specimens of the mammals mentioned above except Capricornis crispus found in the respective regions is presented to give an idea of the diversity of mammalian fauna.

23. Extant and extinct of large mammals

   The distribution of Macaca fuscata at 1923 and at 1978 is compared. Extinction and distribution of the eight mammalian species mentioned above are presented by regions to show the trends.

25. Distribution of breeding birds

   This is an overview of distribution of birds known to breed within Japan. Distribution of birds representing different habitats are presented on separate maps. Birds in alpine and montane forests: Picus canus, P. awokera, Cuculus canorus, and Lagopus mutus; those in forests of hills and villages: Ninox scutulata, Zosterops japonica, Sturnus cineraceus and Corvus macrorhynchos; waterfowls: Gallinula chloropus, G. hardwickii, Podiceps ruficollis, and Ixobrychus sinensis; swallows seen in urban areas: Hirundo rustica, H. daurica, Delichon urbica, and Riparia riparia; and game birds: Phasianus colchicus, Ph. soemmerringii, Bambusicola thoracica, and Coturnix coturnix.

26. Number of avian species

   Distribution of number of species of birds found in the respective localities in the Kanto Region is presented, to express the diversity of natural environment with the diversity of avifauna.

27. Migration of migratory birds

   More than eight-tenths of the birds species found in Japan are migrating birds, and Japan is on an important location for migration of birds. Places of immigration and the number of immigrants of Cygnus cygnus, geese, ducks, and large waders are presented.

29. Distribution of amphibians and reptiles

   The distribution of endangered or scientifically important species of reptiles and amphibians are presented.

   The distribution of Onychodactylus japonicus and Rhacophorus arboreus is wide, while the distribution of Salamonandrella kyeserlingi, Hynobius abei, H. dunni, and Gekko tawaensis are localized. The distribution of Hybobius nigrescens sadoensis and H. okiensis are limited to islands.

   Many species living in flatlands are endangered, expecially around large cities. The habitats of those living in mountainous areas also are decreasing due to human activities.

31. Distribution of insect

   Through investigation of the distribution of insects, which are good indices of environment, changes in the natural environment are detected. Of insects requiring specific environments as habitat, Epiophlebia superstes, Tanypteryx pryeri, Nannophya pygmaea, NOTOPTERA, Lethocerus deyrollei, Terpnosia vauca, Luehdorfia japonica, L. puziloi, Sasakia charonda and Luciola crusiata are used as indices.

32. Extinction and decreases of insects

   Of the 10 species of insects mentioned above, the causes of decrease and extinction were investigated to find out the trend of degradation of the environment.

35. Rivers and lakes

   Due to the narrow land and steep topography, the rivers of Japan are short and their river beds are steep. They carry a huge amount of sand and gravel from the mountainous areas to the bottomlands and deposit them before running into the sea. Water systems develop well all over the country and thier density is not much different among regions. The catchment areas of rivers are generally small.

   There are 487 natural lakes larger than 1 hectare in surface area and their total area is 2400 sq. km, occupying 0.64 per cent of our land area. Many of them are found in eastern Japan and very few are in Shikoku and Kyushu; 131 are in Hokkaido, 328 in Honshu, 1 in Shikoku, and 25 in Kyushu including Okinawa.

36. Alteration of riverbanks

   The whole country was dividied into 13 blocks by large mountain ridges and alteration of riverbanks is expressed by the extent of the construction of embankments on 113 rivers with a total length of 1,121,395 kilometers, in these blocks.

   Rivers are altered with the purpose of utilization and control of water by construction of dams on mountainsides and modification of channels and construction of embankments in flatlands.

37. Natural environment of the Tama River

   As an example of the natural environment of rivers and their drainage basins, the alteration of riverbanks, water quality, and fauna and flora of the Tama River are presented.

38. Alteration of shores of lakes, land use, transparency

   As an example of the natural environment of rivers and their drainage basins, the alteration of riverbanks, water quality, and fauna and flora of the Tama River are presented.

39. Natural environment of Lake Biwa

   The landscape of the shores, temperature, pH and transparency of water, and fauna and flora in the drainage basin of Lake Biwa are presented as an example of the natural environment of lakes and their surroundings.

40. Distribution of freshwater fishes

   The distribution of freshwater fishes in basins of nine important rivers is presented. The life of freshwater fishes differs according to the river, reflecting the regional features and gradient of river beds.

NATURAL ENVIRONMENT OF MARINE AREA

44. Alteration of seacoast

   The total length of the coastline of Japan is 32,170 kilometers and the length per unit land area is far greater than in most other countries, indicating the complexity of the topography of coastal areas.

   The coastlines are grouped into natural, semi-natural, and artificial coasts and their alteration is described.

45. Distribution of tideland, seaweed beds and coral reefs

   About 50,000 ha of tideland are found in Japan, among which coastal ones occupies the largest areas, estuarine one come to the second place and those in lagoons are smallest in areas.

   On the Japan-Sea side are less tidelands than on the Pacific side because of smaller tidal ranges.

   The total area of seaweed beds in Japan amounts to ca. 200,000 ha. They include beds of Laminaria, Eosenia, Sargassum, Undaria, Gostera, small perennial algae, and small annual algae.

   The total area of coral reefs is ca. 90,000 ha and are classified into table-like, branchy, and lumpy corals.

46. Disappearance of tidal beaches

   Before 1945 there were 82,621 hectares of tidal beaches in Japan, but more than three-tenths of them disappeared before 1968. The main causes of the disappearance are filling-in and drainage, of which filling-in represents more than 60 per cent.

47. Living organisms of the tidal zone

   The tidal zone was divided into a spray zone and high, medium and low tidal zones and their biological composition was presented for representative areas. The biological composition is an important index of marine environment because the tidal zone is very susceptible to the influences of human activities.

48. Occurrence of red tide

   From April 1973 to March 1978 in all Japan red tide occurred 2,168 times for a total durstion of 15,165 days. Among the causal organisms of red tide, diatoms noctilucas, and dinoflagellates were most important. Duration of one occurrence of red tide was longer when caused by diatoms and shorter when caused by blue algae.

CONSERVATION OF NATURAL ENVIRONMENT

49. Nature Conservation Areas

   The Nature Conservation Law clarifies the basic ideas of conservation of the natural environment and aims to promote systematic conservation of the natural environment, together with other laws concerning the conservation of the natural environment. Here are presented the Nature Conservation Areas designated on the basis of this law.

Wilderness Areas: 5 items, ca. 5,600 ha

Nature Conservation Areas: 8 items, ca. 7,400 ha

Prefectural Nature Conservation Areas: 445 items, ca. 78,000 ha

50. Natural Parks

   The Natural Parks Law aims to contribute to the bealth, recreation, and culture of the people by conserving excellent natural scenery and by promoting its utilization.

   Here are presented the locations of nature parks established on the basis of this Law.

National Parks: 27 items, ca. 1,250,000 ha

Quasi-national Parks; 52 items, ca. 1,250,000 ha

Prefectural Natural Parks; 283 items, ca. 1,250,000 ha

51. Wildlife Protection Areas

   The Law concerning Wildlife Protection and Hunting aims to improve environment and to promote agriculture, forestry, and fishery by conserving and propagating wildlife by conservation activities and regulation of hunting and by controling harmful birds and animals.

   Here is presented the locations of Wildlife Protection Areas. There are National as well as Prefectural Wildlife Protection Areas.

52. Distribution of hot springs

   The Hot Springs Act aims to contribute to public welfare by protecting hot springs and regulating their use. Here are presented locations of hot springs as important natural resources according to the standards provided by the Law. The location of People's Spas, which are designated by the Director General of the Environment Agency based on the Law as suitable for recreation and rest, are also presented.

   There are many hot springs in Japan; as of March 31,1981, ca. 20,000 springs were registered with a total flow of 1,690,000 liters per minute of hot water. the number of spas is ca. 2,100 among which 69 are designated as People's Spas.

53. Historic sites, places of scenic beauty and natural monuments

    Historic land preservation areas

    Conservation area of green space

   Cultural assets designated by the law for the Protection of Cultural Properties consist of important cultural assets, important non-material cultural assets, important folkloric materials and historic sites places of scenic beauty, and natural monuments.

   To protect the historical landscape of old cities, the Law concerning Special Measures for the Preservation of Historic Landscapes in Ancient Cities was enacted in 1966. Historic Land Preservation areas are designated on the basis of this law, and various kinds of regulations and measures for protection of the areas are carried out.

   Conservation Areas of Green Space are designated in the Metropolitan area and Kinki Region. The legal basis for them is the Law for the Conservation of Green Belts around the National Capital Region and the Law for the Development of Conservation Areas in the Kinki Region.