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Abies sachalinensis dominates the alluvial fan head of the Ochiushinai Gully on Rishiri Island, Japan. This species is able to adapt to frequent disturbances by debris flows. Even-aged stands composed of A. sachalinensis or Alnus maximowiczii were found along the channel, and standing dead trees buried by debris flows were discovered at the alluvial fan head. We used dendrochronological data in order to analyse the geomorphic history of the fan head. We determined the master ring-width chronology by synchronizing ring-width variations in living trees. This master chronology was used to cross-date the establishment and death of the buried trees. Results indicated that most of the buried trees were established in the 1870s and died in the early 1950s. Further, debris flow was estimated to have occurred in the 1890s and the late 1960s based upon the distribution of even-aged stands seen in aerial photos. The ring-width variations of the trees adjacent to the channel indicate a low correlation for synchronization, while those located on the hillslope have a high correlation. A low correlation in the riparian trees can be attributed to the instability of geomorphic surfaces caused by debris flow disturbances.

Recentry, two populations of the Japanese Ptarmigan are found on Mt. Hiuchi (8, 075 ft.) and Mt. Yakeyama (7, 872 ft), Kubiki Mountain Range, northern part of central Japan (Fig. 1). Oen sub-adult group of the bird was observed on Mt. Yakeyama in 1969, which suggested a possibility of its breeding on the mountain.The ptarmigan is one of the national monuments in Japan. Few ecological observations on the ptarmigan are carried out on Mt. Fuji (12, 385 ft.), Mt. Hiuchi and Mt. Iizuna (6, 288 ft).Extinction of the ptarmigan caused by human works on Mt. Fuji (the highest mountain in Japan) was reported by Chiba in 1971.Detailed observations of the ptarmigan on Mt. Yakeyama were made during June 24-28, 1971 to get some ecological informations. Vegetations of the mountain, size and structure of the population, their nest and eggs and evaluations of their habitat are reported on this paper.Mt. Yakeyama is a cone-shaped mountain that has a large crater on the top. The top has a very poor vegetation causing by active volcano. Some patches of Pinus pumila are found on southern slope near the top, and Alnus maximowiczii surrounds the mountain (Fig. 6).Two pairs of ptarmigan showed up on the southern slope above 7, 544 ft. high. One nest containing six eggs nearly hatched was found in deep Pinus pumila bush (Fig. 3).Summer and winter droppings (Figs. 2-a, 2-b) and sandbaths are marked on the map (Fig. 5).This seems to show their habitat on this mountain.They come down to get foods (buds appearing on snow) as low as 5, 904 ft. in winter, on the other, in summer they stay mostly around the top to avoid terrestrial predators.A few ptarmigans were observed in early spring and late fall on Mt. Myoko (8, 023 ft.) where no nest had been reported. These records suggest the possibility of temporary shortdistance migration in snow season.Breeding site of the bird supposed to be restricted to pine bush on this mountain. Two or three breeding pairs supposed to lay their eggs in this bush (the second pair would lay their eggs after the first nestlings were fledged): they seem to use the same nesting site alternatively. In many cases, chickens of the Japanese Ptarmigan were found in June in other mountains whereas some immediately after hatched were observed on Mt. Yakeyama in August.

The Fennoscandian mountain birchwoods and the ecologically and physiognomically closely related oceanic coastal birchwoods are found in all the boreal zones (northern boreal, middle boreal, southern boreal and hemiboreal) in Europe. In general, they are characteristic and commonly dominant (not necessarily in pure stands) in the oceanic to suboceanic, cool and windy western sections of the boreal zones. The same pattern is clearly repeated on the east coast of Eurasia, despite of its less pronounced oceanity. There the most oceanic boreal sections are dominated by forests of Betula ermanii s. lat. (ranging from the northern boreal to the hemiboreal zone) and Alnus maximowiczii (essentially middle and northern boreal). The western North American Alnus sinuata woods may be interpreted as homologous to the Fennoscandian birchwoods. They are found mainly in the middle and northern (upper) boreal zones in southern Alaska (also in the mountains of British Columbia and SW Yukon). In southern Alaska there are also some fragments of oceanic birchwoods. In eastern North America such homologous deciduous forests are poorly developed. Among the true inland mountain birchwoods only those of the northern Ural Mts., some Transbaikalian mountains, the Himalaya and (with reservation) the Caucasus are referred to the distinct homologies of the Fennoscandian birchwoods. The widespread timber-line alder scrubs consisting of Alnus crispa and related taxa in North America and Eurasia are not included in such homologies. The occurrence of treeless boreal maritime heaths and grasslands is closely related to the distribution of birch and alder forests. The lowlands of Iceland, the Aleutian Islands and the Kuril Islands, for instance, are referred to the boreal heath sections rather than to the arctic.

The White-tailed Eagle Haliaeetus albicilla is the only sea eagle that breeds in Hokkaido. Its breeding area is restricted to the northern and eastern coasts of Hokkaido. This species also breeds in the Kurile islands and is a rare or uncommon winter visitor in Honshu, Shikoku, Kyushu, Ryukyu and their adjacent islands. Although there are several reports on the nesting of this eagle in Hokkaido, the breeding biology of the Japanese population has been virtually unknown. The present study has been conducted for sixteen years since 1963, and sixteen nests with eighteen nestlings were examined by the author. The results are summarized as follows:(1) Almost all nests were found on the branches of big trees near the sea, but some of them were located in trees near lakes or river-sides surrounded by abandoned grasslands. Although in northern Europe the eagles normally nest on rocks, the author did not have observed any nest built on rocks despite of rocky coast lines in the northeast part of Hokkaido. A nest was found on a tree only 350 m from human habitation. Another was observed near the side of a lake 25 km away from sea.(2) As a rule, nesting trees were situated on the upper part of hill-sides, from which a wide area can be viewed.(3) The elevations of the nesting sites are from 5 to 380 m above sea-level.(4) The kinds of trees in which the nests were found are as follows: Picea jezoensis, Betula ermani, Alnus maximowiczii, and Abies sachalinensis. The diameter of the nesting tree trunks is 20 to 128 cm (average 65 cm).(5) The nest is normally somewhat egg-shaped. The external diameter was 91 to 183 cm, and the inside diameter 65 to 120 cm. The thickness of the nests was 40 to 202 cm (average 86 cm).(6) The height of the nests from the ground was 16.5 to 25.0 m.(7) Nest building by both sexes was observed throughout the year but most active in March. In Hokkaido most eggs are laid in March.(8) The reinforcement of their nests was made continuously during the breeding season. the parents bringing nesting materials even during incubation.(9) Nest materials were composed of tree sticks or twigs from Pica jezoensis, Betula ermani, Alnus maximowiczii, etc. The biggest piece of stick was 50 cm long and 3 cm in diameter. The nest materials varied depending on the nesting place and its surrounding environmental conditions.(10) The leaves and barks of the following plants were used for lining: Alopecurus pratensis, Sasa veitchii, Phragmites communis, Hydrangea petiolaris, Betula ermani, Abies sachalinensis, Zostera marina etc.(11) The exact date of egg-laying is unknown, but eggs are apparently laid in mid-March. This is estimated from the incubation period and the hatching date. The incubation period was known as 37 to 40 days whereas the young hatched in early May in the study area.(12) The new born young were covered with pale grey down and looked very vulnerable. The young immediately after hatching had weights about 110 to 115g. Their call seems to be cheep or churi, churi.(13) Branches with green leaves were frequently found in the nests. They were used by the young probably for hiding, shading or a windbreaker, etc.(14) The fledging time varied with individual conditions. The minimum fledging time was about 70 days and the maximum about 90 days. The earliest nestling left their nest on 21 June and the latest one left on 7 August. Fledglings often returned to the nest after fledging and received food from their parents.(15) When two nestlings were in a nest, the smaller one perished when food was scarce. In most cases, the older chick ate the younger one.(16) Foods brought to the nestlings by parents were observed by using a telescope and binoculars. Samples were also collected from the nests.