evergreen conifer forests in hokkaido

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In: Evergreens Editors: Adriano D. Bezerra and Tadeu S. Ferreira

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Chapter 1

EVERGREEN CONIFER FORESTS IN HOKKAIDO AND SAKHALIN: DISTRIBUTION, ECOLOGY, AND HISTORY SINCE THE LAST GLACIAL PERIOD Yaeko Igarashi and Tsuneo Igarashi 1

Institute of Paleoenvironment of Northern Regions; 2 Faculty of Agriculture,Hokkaido University, Japan

ABSTRACT Hokkaido (Japan) and Sakhalin (Russia) are islands located in temperate East Asia, in the northwest Pacific area. Evergreen conifers such as Picea jezoensis, Abies sachalinensis, and Picea glehnii are found on both islands, which were connected via the Soya Land Bridge during the last glacial period. In Sakhalin, P. jezoensis is distributed throughout the area, mixed with Larix gmelinii and Pinus pumila in northern and central parts of the island. Abies sachalinensis is mixed with P. jezoensis, except in the north, and forms pure forests in southern Sakhalin. The distribution of P. glehnii is restricted to only southern Sakhalin. In Hokkaido, these evergreen conifers form a mixed forest together with cool-temperate broadleaf trees in most areas, except in southwestern Hokkaido. This chapter describes the distribution and ecology of these evergreen conifer forests in Hokkaido and Sakhalin, which were mainly investigated by the late Prof. Misao Tatewaki (1943, 1958). The histories of evergreen conifer forests since the last glacial period were reconstructed based on pollen records obtained from three sites in Sakhalin and ten sites in Hokkaido. The P. jezoensis forest, which developed during marine isotope stage (MIS) 3 on both islands, was replaced by Larix gmelinii–Pinus pumila forest during MIS2 as the climate changed from cool/moist to cold/dry. In west-central Sakhalin, this forest was replaced by P. jezoensis forest around 10,000 years before present (yr BP). In northern and central Hokkaido, Larix gmelinii-dominant forest was replaced by Quercus-dominant forest about 8,000 yr BP. Picea glehnii forest formed about 13,000 yr BP in highland bogs, and about 10,000 yr BP in lowland bogs. The abundance of the evergreen conifers Picea jezoensis, Picea glehnii, and Abies sachalinensis increased slightly several years ago on both islands.

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I. PREFACE Hokkaido and Sakhalin are islands located on the eastern edge of the Asian continent. The shortest distance between the two islands is about 45 km. Bottom depths of the Tatar Strait between the Asian continent and Sakhalin, the Soya Strait between Sakhalin and Hokkaido, and the Nemuro Strait between Hokkaido and the South Kuril Islands are shallower than 60 m. During the last glacial period, land bridges connected the Asian continent, Sakhalin, Hokkaido, and the South Kuril Islands, forming the Paleo-Peninsula of the Asian continent (Ono, 1990; Figure1). The land bridges allowed for migration of animals, plants, and humans from northeastern Asia and Sakhalin to Hokkaido and the South Kuril Islands, as suggested by the existence of common species of plants and animals among these islands. In particular, the islands share the same species of main evergreen conifers. The main evergreen conifers found in Sakhalin and Hokkaido are not distributed in Honshu (with the exception of Picea glehnii on the Mt. Hayachine in northern Honshu), which remained separated from Hokkaido by the Tsugaru Strait during the last glacial period. In this chapter, we discuss the present distribution and ecology of major evergreen conifers in Sakhalin and Hokkaido and reconstruct their history since the last glacial period based on pollen analysis.

Figure 1. Vegetation map of Sakhalin (Russia) and Hokkaido (Japan), also showing straits around 2 islands, shore line during the last glacial period and demarcation line of plant distribution; Schmidt’s line, Miyabe line and Kuromatsunai lowland.

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II. REGIONAL SETTING 1. Sakhalin Sakhalin is a slender island in Russian Far East that stretches from 45°53′N to 54°23 ′N and is north of Hokkaido. The climate in Sakhalin is influenced by sea currents and northwest monsoon. The Tsushima Current flows northward through the Sea of Japan along the southwest coast of Sakhalin. The East Sakhalin Current, originating from Siberia, flows south along the east coast in the Sea of Okhotsk (Figure2). In winter, the northwest monsoon from Siberia generates extremely low temperatures. In addition, sea ice, which forms in the northern parts of the Sea of Okhotsk, flows south. As a result, the Sea of Okhotsk region has cold and dry winters. The geological structures of Sakhalin were formed by tectonic movement, sedimentation, volcanic activities, and metamorphism, which mainly occurred during the Cretaceous period (Rozhdestvensky, 1986). Sakhalin is divided into three zones: the West Sakhalin zone, East Sakhalin zone, and suture zone. The central depression extends in the suture zone. The Susunai lowland (which developed in the south) and the Tym-Poronay lowland (which developed in central Sakhalin) form the central depression and are connected to the central depression in Hokkaido. The North Sakhalin Plain is composed of low hills and plateaus, and many lagoons exist along the eastern coast of northern Sakhalin.

Figure 2. Sea currents around Sakhalin and Hokkaido.

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2. Hokkaido Hokkaido is the northernmost main island of the Japanese Archipelago. Located between 41°23′ and 45°31′N, and 139°45′ and 145°47′E, Hokkaido is surrounded by the Pacific Ocean, the Sea of Japan, and the Sea of Okhotsk. The natural environment in Hokkaido is affected by marine currents and the northwest monsoon. The Kuroshio Current flows northeastward along the eastern coast of Japan and partly flows out near eastern Hokkaido. The Oyashio Current flows southwestward along the eastern coast of Hokkaido (Figure2). The meeting of these currents off the eastern coast of Hokkaido results in the formation of dense sea fog during summer in the easternmost region of Hokkaido and in the southern Kuril Islands. The Tsushima Current flows northeastward along the western coast of Japan in the Sea of Japan, flowing into the Pacific Ocean through the Tsugaru Strait between Hokkaido and Honshu and into the Sea of Okhotsk through the Soya Strait between Hokkaido and Sakhalin. The northwest monsoon is caused by differences between the Siberian high and Aleutian low in the north Pacific. Extremely cold, dry Siberian air masses crossing the Sea of Japan receive heat and water vapor from the sea surface where the Tsushima Current flows and produce heavy snowfall on the western coast of Hokkaido during the winter. Hokkaido is divided into three geologic regions (Editorial Committee of Hokkaido, 1990). The west province is the northern extension of the Northeast Honshu arc. Sedimentary rocks, as well as volcanic rocks and pyroclastic rocks which erupted during the Neogene to Quaternary eras, are deposited over Mesozoic rocks. The west province contains many active volcanoes and caldera lakes. In the central province, the Hidaka Mountains (formed by the Hidaka orogenesis during the Mesozoic and Neogene eras) stretches north-south. On the summits of the Hidaka Mountains (Figure3), glacial evidence cirques formed during the last glacial period. Mt. Asahi-dake (2290.3 m a.s.l.), located in the Daisetsu volcano group, is the highest mountain in Hokkaido (Figure3). In the central province, the central depression zone is formed in a south-north direction and contains plural basins. The geologic structure of the central province extends to the central depression in Sakhalin. The east province is located in the southwest part of the Kuril arc. The volcanic front, which runs in parallel with the Kuril arc, forms the Akan-Kussharo volcano group (Figure3) in Hokkaido. The Nemuro Peninsula is composed of Cretaceous rock, which is distributed in an east-west direction.

III. CONIFEROUS FOREST IN SAKHALIN AND HOKKAIDO 1. Coniferous Forest in Sakhalin Sakhalin belongs to the western Okhotsk dark-conifer forest zone (Kolesnikov, 1961). Sub-maritime and maritime climates occur in the middle and southern areas of the forest zone (Krestov, 2003). On the north and west, this forest zone borders the eastern Siberian larch area, and in the south it contacts the northern mixed-forest area.

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Figure 3. Location map of studied site in Hokkaido. 1. Numaura Mire, Rishiri Island 2. Minamihama Mire, Rishiri Island 3. Mt. Suribachi, Toikanbetsu 4. Nakamine no Daira 5.Pankenai Mire and Kotohira no Sawa 6. Kenbuchi Basin 7. Daisetsu volcano group 8. Mt. Kuro-dake 9. Furano Basin 10. South of the Central Massif 11. Hidaka Mountains 12. Mt. Apoi-dake 13.Nopporo Hills 14.Mt. Tarumae 15.Kyougoku Mire 16. Mt. Yohtei 17.Esashi 18.Akan-Kussharo volcano group including Atsanupuri, Mt. Meakan-dake, Mt. Oakan-dake, Mt. Mashu-dake, Lake Kussharo, Nogami Pass, Kenga mine, Kawayu, Onneto, Mt. Makuwanchippu,Mt. Sawanchippu and Akan National Park 19. Chanai 20. Ochiishi Mire 21. Habomai Bog 22. Shunkuni Tai 23. Hurukamappu.

The evergreen conifers in Sakhalin are Picea jezoensis (Yezo spruce), Abies sachalinensis (Todo fir), Picea glehnii (Glehn’s spruce) and Pinus pumila (stone pine). Tsuga sp., which is an extinct species in Sakhalin and Hokkaido, survived in Sakhalin until the late Holocene (Igarashi,Y., 2010). The Picea jezoensis forest covers the majority of Sakhalin. Abies sachalinensis is scattered throughout the spruce forest in central and south Sakhalin, and pure fir stands are found in southern Sakhalin. In the northernmost parts of Sakhalin (the Schmidt peninsula), Picea jezoensis exists in the absence of fir (Figure1). Pinus pumila grows in the spruce forest in north, central, and southern mires. Currently, distribution of Picea glehnii is restricted to southern Sakhalin. The northern limit of Picea glehnii is located at approximately 46°48′N, 142°37′E, in southern Sakhalin (Tatewaki, 1943). The deciduous conifer Larix gmelinii (larch) is an important component of the spruce forest in the northern and central areas and is distributed in mires in southern Sakhalin (Figure5).

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Figure 4. Regions of the northeastern Far East A: Intermediate region (Pan-mixed forest zone) B; Temperate East Asiatic Region C. Siberian Arctic Region D. Eastern Central Asiatic Region (after Tatewaki, 1961b).

Figure 5. Distribution area of Picea glehnii forest (after Tatewaki and Yamanaka, 1938; Ishizuka, 1961).

2. Coniferous Forest in Hokkaido First, we introduce the horizontal distribution of the forest in Hokkaido. The forest developed in lowland areas (< 500 m a.s.l.) is divided into two regions. South of the Kuromatsunai Lowland, in southwest Hokkaido (Figure1), is the cooltemperate forest zone which continues from northern Honshu. Fagus crenata is the most common tree in this zone. The region of Hokkaido that is north of the Kuromatsunai Lowland is included in the same vegetation zone as the area south of the Miyabe Line (Figure1;Tatewaki, 1947). The Miyabe Line lies between the South Kuril Islands and the

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region south of Schmidt’s Line (Figure1; Kudo, 1927), established in central Sakhalin, northeast China, and Primorskii Krai, Russia. Tatewaki (1961b) termed these botanically homologous areas the “Pan mixed forest zone” (Figure4). In this botanical zone, boreal species and temperate species mix as single trees and/or mix as stands. North of the Kuromatsunai Lowland, boreal species such as Picea jezoensis, Picea glehnii, and Abies sachalinensis mix with temperate species such as Ulmus davidiana var. japonica, Acer mono, Quercus mongolica var. grosseserata and Tilia japonica. In this region, 56 tree species and about 44 shrub species have been identified. In the south of the Kuromatsunai Lowland, the representative tree Fagus crenata has a northern distribution limit. An additional 29 species of trees and shrubs, including Thujopsis dolabrata var. hondae, Salix gilgiana, and Pterocarya rhoifolia, also have the northern distribution limit in this area. Other species spread from their habitats to north of the Kuromatsunai Lowland, such as Quercus mongolica var. grosseserata, Tilia japonica, Acer mono, Ulmus davidiana var. japonica, Magnolia obovata, Cercidiphyllum japonicum, Cornus controversa, and Fraxinus mandshurica var. japonica. Next, we turn to the vertical distribution of forest. On Mt. Kurodake (Figure3; 1984 m a.s.l.) in the Daisetu volcano group, the central Hokkaido, mixed forest extends lower than 800 m a.s.l; Tatewaki, 1949; Tatewaki and Takahashi, 1955). Taxus cuspidata, Betula maximowicziana, Ulmus laciniata, Tilia japonica, Acer mono, Alnus hirsuta, Fraxinus mandshurica var. japonica, Kalopanax pictus, Acer japonicum, Prunus buergeriana, Sorbus commixta, Picea jezoensis, Abies sachalinensis, Picea glehnii, Acer ukurunduense, Betula ermanii, and Alnus maximowiczii have been identified in this mixed forest. Coniferous forests are found between 800 and 1500 m a.s.l. In this zone, Picea jezoensis, Abies sachalinensis, Picea glehnii, Acer ukurunduense, Betula ermanii, Acer japonicum, Prunus buergeriana, Sorbus commixta, Sorbus matsumurana, and Alnus maximowiczii have been identified. Between 1500 m and 1800 m a.s.l. is the Betula ermanii forest zone. The Betula ermanii forest also includes Acer ukurunduense, Sorbus matsumurana, and Alnus maximowiczii. The Pinus pumila zone occurs in mountains higher than 1800 m a.s.l. Alnus maximowiczii and Sorbus matsumurana mix with the Pinus pumila forest.

IV. DISTRIBUTION AND ECOLOGY OF EVERGREEN CONIFERS IN HOKKAIDO AND SAKHALIN The evergreen conifer forests (Picea glehnii forest, Picea jezoensis forest, Abies sachalinensis forest, Picea jezoensis-Abies sachalinensis forest, and the Pinus pumila thicket) are distributed in the mountain areas higher than 500 m a.s.l. in Hokkaido. These evergreen conifers are often mixed with temperate broadleaf trees in the northern areas than the Kuromatsunai Lowland which is considered to be the geobotanical demarcation line, and lower than 500 m a.s.l. in the northern areas. In the northern areas than the Kuromatsunai Lowland the boreal and temperate forests are adjacent to each other and/or single tree of the boreal and temperate elements mix in the forest.

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Taxus cuspidata, which is not a major evergreen tree in Hokkaido, is usually one component of the forest. However, Taxus cuspidata forms a pure forest mainly in eastern Hokkaido. All these forests create a mosaic in which temperate and boreal characteristics intermix. Tatewaki (1958) called this intermediate zone the “pan mixed forest zone”. Temperate forests developed south of the Kuromatsunai Lowland are mainly composed of Fagus crenata, which spreads to northern Honshu. The beech forest is partially mixed with Thujopsis laetevirens and/or Pinus parviflora var. pentaphylla. The Picea jezoensis forest encompasses all of Sakhalin. Abies sachalinensis forest is found in the central and southern regions, but in the south it forms a pure forest. Pinus pumila forest mainly distributes in the north and on the mountains. The distribution of Picea glehnii forest is restricted to southern Sakhalin. In this chapter, we discuss the distribution and ecology of the evergreen conifer forests in Hokkaido and Sakhalin. The stands discussed were surveyed using a belt-transect method. The purpose of community analysis is to clarify whether the sociation (which is a unit in a community) and plant taxonomy are in agreement. For forests extending more than 1 ha, the forest is named according to the main species (coverage 4-5) and/or predominant species (coverage 3). The sociation name of a forest that extends in at least 5 ha is decided by the main species (coverage 4-5) or predominant species (coverage 3) on the forest floor and/or lower layer. If a forest has multiple layers, we use the mark 「-」, and if two to three dominant species are included in the upper layer, we use the mark 「・」. The survey was performed using the belt-transect method, with 5 m wide by 50 m long belts. The field survey recorded all trees that appeared in a belt and had a diameter at breast height (DBH) of more than 4–6 cm. For these trees, the species, location, height, and DBH were noted. A crown projection diagram and belt-transect of the trees in the forest were then drawn. Forest floor plants were surveyed for every 5 m by 5 m square established along the basal belt. All species in each square were measured, and the coverage of each species was classified into five levels; 5=3/4–1, 4=1/2–3/4, 3=1/4–1/2, 2=1/10–1/4, 1= under 1/10, and += minor. The forest floor plants were roughly classified based on the coverage value (CV) and Frequency (F). Next, we introduce the distribution and ecology of eight representative forests in Hokkaido and Sakhalin.

1. Picea Glehnii Forest Picea glehnii reaches 45 m in height and 1.5 m in diameter. It is durable to climate change and an excellent material quality. Thus, it is one of the main afforestation trees in Hokkaido. Picea glehnii was first identified in 1861 by Peter von Glehn (1835–1876) in a mire along Aniva Bay in southern Sakhalin. Picea glehnii is distributed in most of the study area, except for southernmost Hokkaido. It is also distributed in southern Sakhalin and in the South Kuril Islands (Tatewaki, 1943;Tatewaki andYamanaka,1938). Picea glehnii was also found in 1961 on the northern slope of Mt. Hayachine in northern Honshu (Figure5), where it was considered a relict stand (Ishizuka, 1961).

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Picea glehnii forests are distributed in unique habitats. The community in Picea glehnii natural forest was investigated by Tatewaki and Morimoto(1933). Tatewaki (1943, 1958) classified its habitat into seven areas: bog, mire and swamp, serpentine district, sand dunes, areas burned by forest fires, volcanic sand and gravel, rocky slope, and vicinity of hot springs. Tatewaki (1958) next recognized 10 sociations in mires in Hokkaido and the South Kuril Islands. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Picea glehnii-Carex middendorffii sociation. Picea glehnii-Phragmites communis-Oxicoccus quadripetalus sociation. Picea glehnii-Ledum palustre sociation. Picea glehnii-Eriophorum vaginatum sociation. Picea glehnii-Moliniopsis japonica sociation Picea glehnii-Osmunda cinnamomea sociation. Picea glehnii-Carex cespitosa sociation. Picea glehnii-Phragmites communis sociation. Picea glehnii-Lysichiton camtschatcensis sociation. Picea glehnii-Equisetum palustre sociation.

Alternatively, Haruki and Matsuda (1992) recognized two sociations: Picea glehniiLedum palustre var. diversipilosum sociation and Picea glehnii-Pinus pumila-Ledum palustre var. diversipilosum sociation in mires along Aniva Bay in southern Sakhalin.

Photo 1. Picea glehnii forest on the Nakamine no Daira, Teshio Mountaines, northern Hokkaido (Tatewaki and Igarashi, T., 1971) photo by Igarashi, T.

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Picea Glehnii Forest in Bogs Tatewaki and Igarashi,T. (1971) investigated the Picea glehnii forest in the Nakamine no Daira bog,Teshio Mountains in northern Hokkaido (Figure3, Photo1). Located at 44°59′ N, 142°08′E and 420 m a.s.l., this small, round bog is approximately 200 m in diameter and situated on the flat ridge between two low rises. The ridge is in the northern part of the Teshio Mountains composed of the Cretaceous Yezo group in the central province. In the central part of the bog, dwarf Picea glehnii grow sporadically. The tree heights are 0.5–1 m, and basal diameters are 5–10 cm. Toward the edge of the bog, trees grow higher and thicker than in the center of the bog. The forest at the bog edge is Picea glehnii forest mixed with Alnus hirsuta, Acanthopanax sciadophylloides, and Betula ermanii. We established a belt-transect (1 m wide and 150 m long) from the center of the bog in the east direction. Changes in the Picea glehnii forest and vegetation in the east-west direction are shown in Figs.6. Between the center and 38.9 m east of the center, a dwarf Picea glehnii forest is developed. Thirty-seven of the Picea glehnii in the transect were shorter than 1 m and seven were 1–2 m high. Basal diameters were less than 4 cm in 37 of the Picea glehnii and 4–10 cm in six Picea glehnii. The maximum basal diameter was 18 cm. All Pinus pumila (10) were shorter than 1 m(Figure6). Sasa species do not grow in the dwarf forest. Pinus pumila, Juniperus communis, Ilex crenata var. paludosa, Empetrum nigrum, Oxycoccus quadripetalus, Drosera rotundifolia, Hosta atropurpurea, Heloniopsis orientalis, and Gentiana triflora var. horomuiensis grow sporadically. In contrast, Rhynchospora alba, Eriophorum vaginatum, Carex michauxiana, Carex pauciflora, and Moliniopsis japonica are very common. The medium-sized Picea glehnii (4–6 m in height and 10–14 cm in basal diameter) grow thickly at 38.9 to 111.8 m from the center of the bog. On the forest floor, Pinus pumila (higher than 1m) Sasa kurilensis (0.5–1.0 m high) grow, as well as Ilex crenata var. paludosa, Ilex sugeroki var. brevipedunculata, Leucothoe grayana var. oblongifolia, Menziesia pentandra, Vaccinium smallii and Vaccinium ovalifolium. The herb layer contains thick coverage by Moliniopsis japonica and Eriophorum vaginatum. Maianthemum dilatatum, Platanthera tipuloides, Ephippianthus schmidtii, Anemone yezoensis, and Cornus Canadensis are also found. In the particularly moist areas, Eriophorum vaginatum, Iris setosa, and Lysichiton camtschatcensis have been identified. The high layer of trees appears 111.8–150 m from center of the bog. Six Picea glehnii were identified, with tree height ranging from 13–18 m and DBH ranging from 20–40 cm. The forest floor of the high forest contains thick growth of Sasa kurilensis (3 m high) and Pinus pumila disappears. Shrubs such as Ilex crenata var. paldosa, Leucothoe grayana var. oblongifolia, Menziesia pentandra, Vaccinium ovalifolium, and Vaccinium smallii were found in the Sasa area. In the herb layer, Lycopodium serratum, Anemone yezoensis, Corus Canadensis, Symplocarpus renifolius, Carex blepharicarpa, Ephippianthus schmidtii, and Maianthemum dilatatum can grow. Moliniopsis japonica is the dominant species, and Oxycoccus quadripetalus, Carex michauxiana, Carex pauciflora, and Rhynchospora alba are common in Nakamine no Daira bog. The characteristic feature of this bog is the appearance of Pinus pumila and Juniperus communis. Alternatively, the absence of Carex middendorffii and Andromeda polifolia are also distinguishing features (Photo 1).

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Figure 6. Belt-transect and crown projection diagram in Picea glehnii forest on the Nakamine no Daira (Tatewaki and Igarashi, T., 1971).

The peat layer is approximately 60 cm thick in this bog, and the age of the basal peat is 2,220 yr BP (Igarashi,Y., unpublished). The bog formed around 2,000 yrBP.

Picea Glehnii Forest in the Serpentine Region The serpentine belt extends south to north in the northern region of the geological central province. On the serpentinite, pure Picea glehnii forests are well developed, whereas the other conifers do not develop in this region. Their presence in the serpentine region was mentioned as the Picea glehnii-Sasa sociation by Tatewaki (1958). The Kotohira no Sawa (Figure3) is a tributary of the Teshio River, northern Hokkaido. The upper reach of the Kotohira no Sawa is surrounded by steep slopes. Pure Picea glehnii forest grows in a 120 ha area on the steep slopes (at 44°47′N, 142°09′E). The upper part of the slope is connected to the ridge (550 m a.s.l.), where Betula ermanii forest is developed. On the middle part of the slopes, there are dense Picea glehnii forests. The lower part of the slope is steep, with sporadic occurrence of tall Picea glehnii trees. Here, we focus on sociation analysis of Picea glehnii. The sociation site was the lower part (250 m a.s.l.) of the slope. The belt-transect (10 m wide and 50 m long) was established along the slope incline. Picea glehnii trees in the high layer were 20–29 m high with 40–62 cm DBH. After our survey, Picea glehnii on the slopes were cut down. The trees ranged in age from 300–469 years. This forest was a good sample of a climax forest adapted to the land. In the shrub layer, Daphniphyllum humile, Ledum palustre var. yezoense, Vaccinium smallii, and Viburnum furcatum were identified. On the forest floor, Sasa kurilensis was dominant, and Blechnum nipponicum, Skimmia japonica var. intermedia f. repens, Ilex rugosa, Cornus canadensis, Cirsium kamtschaticu, and Carex blepharicarpa grew, and a few mosses were recognized in the herb layer. The sociation name of this belt-transect is Picea glehnii-Sasa kurilensis sociation (Figure7, Photo2).

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Figure 7. Belt transect and crown projection diagram in the forest of Picea glehnii –Sasa kurilensis sociation on the Kotohira no Sawa (Tatewaki and Igarashi,1971).

Photo 2. Picea glehnii-Sasa kurilensis sociation on the Kotohira no Sawa, northern Hokkaido (Tatewaki and Igarashi, T., 1971) photo by Igarashi, T.

Picea Glehnii Forest on Sand Dunes At present, very few Picea glehnii forests are found on sand dunes. Tatewaki (1943) reported forests distributed in Hurukamappu, South Kuril Islands ( Figure3 ) , and in Shunkuni Tai (Figure3), eastern Hokkaido, as typical sand dune forests. In Hurukamappu, on Kunashiri Island, Picea glehnii forest is developed on a sand dune 30 m wide and 500 m long.

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Photo 3. Picea glehnii forest on the sand dune on Shunkuni Tai, eastern Hokkaido (Tatewaki, 1943) photo by Igarashi, T.

Dwarf Picea glehnii grows on the sea side of the dune, and the shapes suggest wind erosion. Tree heights are 5–8 m with 10–20 cm DBH. On the forest floor, Cacalia auriculata is dominant, and Dryopteris austriaca, Stellaria fenzlii, Aruncus dioicus var. kamtschaticus, Viola selkirkii, and Oxalis acetosella were also identified. These plants are different from the typical sand dune community. In Shunkuni Tai, Picea glehnii sand dune forests do not exist on the sea side. On the second sand dune, there is very little Picea glehnii, whereas Picea glehnii forests occur on the third and fourth sand dunes. Major tree heights are about 20 m and DBH is mainly 25–40 cm. The maximum height is 30 m and the maximum DBH is 50 cm in diameter. Characteristic features of forest floor plants are absent, and Sasa spp. Maianthemum dilatatum is dominant. Pyrola renifolia, Oxalis acetosella, Cornus Canadensis, Vaccinium vitis-idea, and Vaccinium praestans are also identified. Tatewaki (1958) observed the Picea glehnii sociation on the sand dunes as the Picea glehnii–Maianthemum dilatatum sociation (Photo 3).

Picea Glehnii Forest on Areas Burned by Forest Fires Tatewaki (1943, 1958) observed regeneration of Picea glehnii at Picea glehnii forests burned by forest fires, as well as renewal with Betula platyphylla var. japonica on Mt. Kikin in the Kitami region and also in Oketo, eastern Hokkaido. This sociation was classified as a Picea glehnii-Sasa sociation.

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Yaeko Igarashi and Tsuneo Igarashi

Picea Glehnii Forest on Volcanic Sand and Gravel Picea glehnii forest grows on the volcanic sand and gravel on Mt. Tarumae in central Hokkaido (Figure3), on Atsanupuri, and near the Kawayu hot springs in the Akan-Kussharo volcano group (Figure3), eastern Hokkaido (Tatewaki, 1943). The following sociations have been described for this habitat (Tatewaki, 1958): 1. 2. 3. 4. 5.

Picea glehnii-moss sociation. Picea glehnii-Lycopodium sociation. Picea glehnii-Cornus canadensis sociation. Picea glehnii-Ledum palustre var. diversipilosum sociation. Picea glehnii-Leucothoe grayana var. oblongifolia sociation.

Igarashi, T. (1986) classified the community in the Picea glehnii forest growing on volcanic sand and gravel in the Akan National Park in eastern Hokkaido as follows: Picea glehnii-Sasa apoiensis sociation, Picea glehnii-Sasa senanensis sociation, Picea glehnii-Cornus canadensis sociation, Picea glehnii-Ilex sugerokii var. brevipedunculata sociation, Picea glehnii-Rhododendron brachycarpum sociation, Picea glehnii-Rhododendron davuricum sociation, Picea glehnii-Vaccinium ovalifolium var. coriaceum sociation, Picea glehnii-Ledum palustre var. yezoense sociation, Picea glehnii-Rumohra mutica sociation, Picea glehnii-moss sociation, Picea glehnii-Abies sachalinensis-moss sociation, Picea glehnii-Pinus pumila sociation. Among these sociations, Picea glehnii-Rumohra mutica sociation and Picea glehniiAbies sachalinensis-moss sociation are described below.

Picea Glehnii-Rumohra Mutica Sociation This community is distributed in the Picea glehnii forest which extends on the slopes of Mt. Meakan to Meakan hot spring in the western foothills of Mt. Meakan (42°3′ 8″N, 143°59′7″ E). The community area is 100 m × 60 m, and similar communities develop in the forest sporadically. The community was surveyed by the belt-transect method. The belt (5 m × 50 m) was established in the pure Picea glehnii forest located at 820 m a.s.l. The Picea glehnii trees were found to be 16–27 m tall, with 14–60 cm DBH. No other tree species were mixed in the forest along the transect. On the forest floor, Rumohra mutica was dominant (average coverage 3), and shrubs such as Ilex rugosa, Menziesia pentandra, and Vaccinium hirtum were also found, as well as the herbs Coptis trifolia and Cornus canadensis. Moss had Frequency V and CV of 1.275. Picea glehnii seedlings were the most dominant (Frequency V, CV 275)among the tree seedlings (0.1–0.3 m in height), which included Picea glehnii, Abies sachalinensis, Pinus pumila, and Sorbus commixta. This Picea glehnii-Rumohra mutica sociation was first recorded in Japan (Figure8, Photo 4). Picea Glehnii-Abies Sachalinensis-Moss Sociation A Picea glehnii forest is distributed near the shore of Lake Akan near the foothills of Mt. Oakan, Akan-Kussharo volcano group. The forest stands on flat sediments of volcanic sand and gravel 40 m above the lake shore (43°27′8″N, 144°6′58″E; 460 m a.s.l.). A belttransect (5 m wide and 50 m long) was established for analysis of the community (Figure 9)

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Figure 8. Belt transect and crown projection diagram in the forest of Picea glehnii-Rumohra mutica sociation on the Mt. Meakan-dake (Igarashi,T.,1986).

Photo 4. Picea glehnii-Rumohra mutica sociation on Mt. Meakan-dake, Akan-Kussharo volcano group (Igarashi,T.,1986) photo by Igarashi, T.

The upper layer of this belt was occupied by Picea glehnii that was 25–31 m tall and 44– 82 cm DBH. In the lower layer, the Picea glehnii was 3–14 m tall,and Abies sachalinensis was dominant, sporadically mixed with Prunus ssiori, Acer japonicum, Sorbus commixta, and Acanthopanax sciadophylloides (Photo 5). On the forest floor, moss species dominated (Frequencies V–III, CV of 1,450–725), and there were many types of herbs and ferns. Among the seedlings (0.1–1.0 m high), Abies sachalinensis and Sorbus commixta were dominant, but there were also a small number of Picea glehnii. Picea Glehnii Forests Near Hot Springs

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Yaeko Igarashi and Tsuneo Igarashi

Photo 5. Picea glehnii- Abies sachalinensis-mosses sociation on the Mt.Oakn-dake (Igarashi, 1986) photo by Igarashi, T.

Figure 9. Belt transect and crown projection diagram in the forest of Picea glehnii-Abies sachalinensismosses sociationon on the Mt. Oakan-dake (Igarashi, T., 1986).

We observed a Picea glehnii forest near Kawayu hot spring in Akan National Park. This park contains forest typical to hot spring areas. The characteristic feature of this habitat is highly acidic soil. Picea glehnii trees in this forest reach 5-7m heights of up to, but rarely exceed, 10 m. On the forest floor, Cornus canadensis and Osmunda asiatica are dominant (Tatewaki, 1943). Along this forest Picea glehnii-Sasa apoiensis sociation is seen (Tatewaki, 1958). Here, Picea glehnii=Pinus pumila-Sasa apoiensis sociation which extends near the fumaroles is mentioned. This is a characteristic sociation along the slope and ends at the fumaroles. The community type is as follows: Picea glehnii = Pinus pumila-Sasa apoiensis

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(two independent sociations); Picea glehnii-Sasa apoiensis and Pinus pumila-Sasa apoiensis combine and form one forest. The community extends 3 km southwest from the Atosanupuri and 0.4 km north from Yunuma, located at 43°36′N, 144°24′11″E, 190 m a.s.l. The community develops around fumaroles of the slope. Pinus pumila forest occur along the fumaroles, and are 5–10 m wide and 1–3 m high, with 2–12 cm root diameters. Picea glehnii forests develop behind the Pinus pumila forest in the narrow belt. In the dense Pinus pumila forest, forest floor vegetation is absent. However, on the open forest floor, Sasa apoiensis, Miscanthus sinensis, and Pteridium aquilinum can grow. The low Hydrangea paniculata and Quercus mongolica var. grosseserata grow sporadically. Picea glehnii in the upper layer of the Picea glehnii forest is 5–10 m high, 8–22 cm DBH. On the forest floor of the Picea glehnii forest, Sasa apoiensis is dominant with a CV of 5–2 (Tatewaki,1958), and a Picea glehnii-Sasa apoiensis sociation is formed (Figure10 and Photo 6).

Photo 6. Picea glehnii=Pinus pumila-Sasa apoiensis sociation on Yunuma, Kawayu (Igarashi, T.,1986) photo by Igarashi, T.

Figure 10. Belt transect and crown projection diagram in the forest of Picea glehnii=Pinus pumila-Sasa apoiensis sociation on Yunuma, Kawayu (Igarashi, T., 1986).

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Yaeko Igarashi and Tsuneo Igarashi

Picea Glehnii Forest on Rocky Slopes Tatewaki (1943, 1958) surveyed the Picea glehnii forest developed on the rocky slope of the Yotei Mt. (Figure3) in central Hokkaido, and on Kitami Okuikutahara in northeastern Hokkaido. He noted that Picea glehnii, which has a strong durability against severe sunlight, temperature changes, and strong winds, formed the pioneer community. The upper layer trees of the Picea glehnii forest reach up to 20–30 m in height, with 40– 60 cm DBH. Moss dominates on the forest floor of the pure Picea glehnii forest. In southern Hokkaido, Rhododendron albrechtii is the dominant shrub on the floor of the Picea glehnii forest. In northern and eastern Hokkaido, Rhododendron brachycarpum is dominant and can coexist with Viburnum furcatum and Rhododendron dauricum. These types of forests all have thin soil and are commonly found in mountain areas in Hokkaido and the South Kuril Islands (Tatewaki, 1958). A unique, pure Picea glehnii forest is found on a gravel slope on the west side of Mt. Meakan (43°22′59″N, 143°58′21″E, 630 m a.s.l.), Akan-Kussharo volcano group. These Picea glehnii trees are 18–25 m high with 24–44 cm DBH. There are no extremely tall trees, and all the trees are of similar size. Rhododendron brachycarpum (1.5–2.0 m high) is dominant on the forest floor. Among shrubs, Vaccinium hirtum is dominant, and Vaccinium praestans, Menziesia pentandra, and Vaccinium smallii are also found. Herbs such as Cornus canadensis and Pyrola faurieana are dominant, and the fern Lycopodium complanatum can grow. Moss is dominant on the surface (Frequency V, CV 4,464). Among the seedlings of tall trees, Abies sachalinensis (0.3~1.5m high) is dominant, and Picea glehnii and Sorbus commixta seedlings were also identified. Considering these findings, this community is considered a Picea glehnii-Rhododendron brachycarpum sociation (Figure11 and Photo 7).

Photo 7. Picea glehnii-Rhododendron brachycarpum sociation on the Mt. Meakan-dake, Akan Kussharo volcano group (Igarashi,T., 1986) photo by Igarashi, T.

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Figure 11. Belt transect and crown projection diagram in the forest of Picea glehnii-Rhododendron brachycarpum sociation on Mt. Meakan-dake (Igarashi, T., 1986).

2. Picea Jezoensis-Abies Sachalinensis Forest The conifer forest in Hokkaido and Sakhalin, excluding the northern region, is composed of spruces and firs. The Picea jezoensis-Abies sachalinensis forest is commonly dominant on both islands. Occasionally, Picea jezoensis forest and/or Abies sachalinensis forest and/or Abies mayriana forest is dominant. In Hokkaido, Picea jezoensis-Abies sachalinensis forests are dominant in the east and north; however, the dominance of these forests decreases in southwestern Hokkaido, where Abies mayriana (which is analogous to Abies sachalinensis) sporadically mixes with the Fagus crenata forest. In the mountains (800–1200 m a.s.l.) of central Hokkaido, Picea jezoensis and Abies sachalinensis are co-dominant (Tatewaki,1954;Tatewaki and Chihiro,1954;Tatewaki and Takahashi,1955). Currently, Picea jezoensis-Abies sachalinensis forest is distributed throughout Hokkaido, Sakhalin, and the South Kuril Islands. Fir forest occurs in the central part of Etorofu Island in the South Kuril Islands. In central-west Sakhalin, Picea jezoensis-Abies sachalinensis forest is widely developed in the mountain regions and forms a dense boreal conifer forest (Haruki and Matsuda, 1992). Populus maximowiczii forest, Alnus hirsuta forest, and Salix spp. forest are distributed along streams, and Betula ermanii forest and Pinus pumila forest develop on the hillsides. In the Picea jezoensis-Abies sachalinensis forest located at approximately 49°54′N, 142°25′E in central-west Sakhalin, Picea jezoensis and Abies sachalinensis are dominant from high to low forest layers. In the low layer, Acer ukurunduense, Sorbus commixta, Vaccinium ovalifolium, and Euonymus tricarpus grow. On the forest floor, Cornus canadensis, Dryopteris austriaca, Lastrea dryopteris, Calamagrostis langsdorffii, Carex spp., Maianthemum dilatatum, and Linnaea borealis have been identified (Haruki and Matsuda, 1992). Forest types and sociations recognized in the Picea jezoensis-Abies sachalinensis forest on Hokkaido were classified as follows (Tatewaki, 1958).

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1. Sasa type. Picea jezoensis-Abies sachalinensis-Sasa sociation. 2. Fern type. Picea jezoensis-Abies sachalinensis-Dryopteris austriaca sociation. Picea jezoensis-Abies sachalinensis-Dryopteris amurensi sociation. Picea jezoensis-Abies sachalinensis-Dryopteris crassirhizoma sociation. 3. Shrub Type. Picea jezoensis-Abies sachalinensis-Rhododendron brachycarpum sociation. Picea jezoensis-Abies sachalinensis-Menziesia pentandra sociation. Picea jezoensis-Abies sachalinensis-Vaccinium ovalifoliu sociation. 4. Carex Type. Picea jezoensis-Abies sachalinensis-Carex sachalinensis sociation. 5. Moss Type. Picea jezoensis-Abies sachalinensis-moss sociation. 6. Non plant-cover Type. sNext, two sociations of Picea jezoensis-Abies sachalinensis forest in Hokkaido are mentioned.

Picea Jezoensis-Abies Sachalinensis-Sasa Senanensis Sociation This forest extends on the Teshio Mountain ridge in Toikanbetsu, northern Hokkaido (Figure3;45°04′N, 142°2′E, 170 m a.s.l.). The higher forest layer is dominated by Picea jezoensis that are 24–28 m high, with 58–68 cm DBH. In the second layer, Abies sachalinensis, which are 12–24 m high with 18–52 cm DBH, are dominant. Kalopanax pictus, Sorbus commixta, and Acer mono of low height also coexist in the forest. Sorbus commixta grows under the open canopy. Viburnum furcatum is the only shrub that was identified in the forest. On the forest floor, Sasa senanensis is dominant with Frequency V and CV 8750 (Figure 12 and Photo 8).

Photo 8. Picea jezoensis- Abies sachalinensis-Sasa senanensis sociation in Toikanbetsu, northern Hokkaido (Tatewaki and Igarashi,T.,1971) photo by Igarashi, T.

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Figure 12. Belt transect and crown projection diagram in the forest of Picea jezoensis・Abies sachalinensis-Sasa senaensis sociation on Toikanbetsu (Tatewaki and Igarashi, T., 1971).

Picea Jezoensis-Abies Sachalinensis-Carex Sachalinensis Sociation This forest stands in the center of the crater basin of the Mt. Mashu-dake (Figure3; 857 m a.s.l.), Akan-Kussharo volcano group. The forest is located at 43°34′6″N, 144°33′14 ″E and 370 m a.s.l. Picea jezoensis (22–27 m high and 38–70 cm DBH) dominate in the upper forest layer. Abies sachalinensis is the only other tree mixed in this forest. In the lower layer, Picea jezoensis, Abies sachalinensis, Taxus cuspidata, Prunus ssiori, and Acer momo are able to grow. Seedlings from Abies sachalinensis, Picea jezoensis, Taxus cuspidate, Prunus ssiori, Fraxinus lanuginose, and Sorbus commixta are also found. Carex sachalinensis is dominant on the forest floor (Frequency V, CV 5,750) and Cacalia auriculata var. kamtschatica, Maianthemum dilatatum, Cirsium kamtshaticum, Oxalis acetosella, and Aruncus dioic were also identified (Igarashi, T., 1986; Figure13 and Photo 9).

Photo 9. Picea jezoensis-Abies sachalinensis-Carex sachalinensis sociation in the volcanic crater on the Mt. Mashu-dake (Igarashi, T., 1986) photo by Igarashi, T.

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Figure 13. Belt transect and crown projection diagram in the forest of Picea jezoensis-Abies sachalinensis-Carex sachalinensis sociation on the Mt. Mashu-dake (Igarashi, T., 1986).

3. Abies Sachalinensis Forest Abies sachalinensis is distributed in Sakhalin, the South Kuril Islands, and Hokkaido (except for the southwest). In southwestern Hokkaido, Abies sachalinensis are replaced by Abies mayriana (Tatewaki and Sugawara, 1953). In the South Kuril Islands, Abies sachalinensis forest extends to the central region of Etorofu Island. Although the forests commonly appear in the lowlands (Tatewaki and Igarashi, T., 1973), they occasionally extend into the mountains, such as at Mt. Meakan, Akan-Kusharo volcano group. Abies mayriana (including Abies sachalinensis)-Cephalotaxus nana sociation is developed in the southwest Hokkaido(Tatewaki and Sugawara,1955). The sociations of Abies sachalinensis forest, as recognized by Tatewaki (1958), are as follows. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Abies sachalinensis-Sasa nipponica sociation. Abies sachalinensis (mayriana)-Sasa kurilensis sociation. Abies sachalinensis (mayriana)-Sasa senanensis sociation. Abies sachalinensis-Sasa borealis sociation. Abies sachalinensis (mayriana)-Dryopteris crassirhizoma sociation. Abies sachalinensis-Dryopteris austriaca sociation. Abies sachalinensis-Carex sachalinensis sociation. Abies mayriana-Cephalotaxus nana sociation. Abies mayriana-Cephalotaxus nana-Daphniphyllum humile sociation. Abies sachalinensis (mayriana)-Daphniphyllum humile sociation. Abies sachalinensis-Rhododendron brachycarpum sociation.

As an example of Abies sachalinensis-Sasa kurilensis sociation, the Abies sachalinensis forest extends into the Nopporo Forest Park is mentioned. The Nopporo Forest Park is located about 14 km east of Sapporo City (Figure3). Abies sachalinensis forests are distributed in the park and designated as special natural monuments.

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A typical Abies sachalinensis-Sasa kurilensis sociation isdeveloped at 42°59′34″N, 141°31′58″E on the hill slope (50 m a.s.l.). The upper layer of the forest is dominated by Abies sachalinensis which is 20–27 m high with 40–58 cm DBH. The lower layer of the forest is dominated by broadleaved trees (