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Biomes and Regions of Northern Eurasia

The Far East

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Kamchatka

Kamchatka is the largest of Russia's peninsulas and extends for about 1200 km in a meridional direction. Four major structures are distinguished within the region (including the nearby islands): the Koryak and Olyutor-Kamchatka systems which form the Koryak-Kamchatka fold belt extending between the Okhotsk-Chukotka volcanic belt and the Pacific; the Kuril-Kamchatka island arc extending from Cape Lopatka (the southernmost tip of Kamchatka) to Hokkaido; and the Komandorskiye islands which form the western segment of the Aleutian island arc (Zonenshain et al., 1990). The most distinguishing feature is high seismic activity and contemporary volcanism: there are 28 active and over 150 extinct volcanoes in Kamchatka and 39 active volcanoes in the Kurils (Deistvuyushie vulkany Kamchatka, 1991; Kozhemyaka, 1994). These are connected to the sub-duction of the Pacific Plate along the Kuril-Kamchatka trench which is situated about 150 km from the volcanic front. Neotectonics and active volcanism are the two major factors shaping the landscapes of Kamchatka. The Pleistocene glaciations, controlled in turn by global climate change and the ongoing building of the mountains, are another important factor.

Structural-lithological complexes within the Koryak-Kamchatka fold belt become successively younger from west to east: while in the Koryak system folding ceased in the late Cretaceous, in the Olyutor-Kamchatka system it continued until the Oligocene-Miocene boundary while the peninsulas of eastern Kamchatka and the Karginsky islands joined Kamchatka in the middle Miocene. The Olyutor-Kamchatka system is mainly composed of the remnants of two island arcs of late Cretaceous and Paleogene age which collided with the margin of Eurasia prior to the Oligocene, while in eastern Kamchatka island-arc volcanism continued through the Oligocene and the early Miocene, with the terrains (e.g., the Kronotsky and Kamchatsky Cape terrains) being brought to the subduction zone and accreted (Zonenshain et al., 1990; Pushcharovsky and Melanholina, 1992). Most active volcanoes occur in the east, extending from the Shiveluch volcano (56°47'N) to the southernmost extremity of the peninsula (Figure 18.5). The active volcanoes of Kamchatka are geologically very young with maximum ages of about 50-40 Ka (Braitseva et al., 1995a, b).

Fig. 18.5 A sketch map of Kamchatka

Morphological Regions and Environmental History

Five distinct morphological regions extending in a sub-meridional direction are distinguished within Kamchatka (Figure 18.5): the West Kamchatka lowland, the Median (Sredinny) Ridge, the Central Kamchatka valley, the Eastern Ridge, and the Eastern Volcanic plateau (Luchinsky, 1974).

The western 80-100 km wide coastal lowland is formed by the thick strata of Cenozoic continental deposits. The coastal zone comprises a number of sandy-clay marine terraces and low and level accumulative plains which are weakly dissected by wide and shallow river valleys. Blanket bogs are widespread on the lowland forming an almost continuous strip along the coastline. The peat is about 3 m thick and locally peat deposits are large enough to be of commercial value. Further inland, the lowland rises gently to the foot of the Median Ridge becoming progressively better drained and less bogged.

The Median Ridge consists of separate ridges and volcanic plateaux with prevailing heights of 1200-1500 m. The ridge has an asymmetrical structure: its western macroslope is gentle while the eastern macro-slope, limited by the Central Kamchatka graben, is very steep. Tectonically, the Median Ridge massif is a continental fragment which collided with the Olyutor arc at the end of the late Cretaceous and which is now overlain by allochthonous cherts and volcanic complexes of the Olytor-Kamchatka system (Shapiro et al., 1986). The northern part of the ridge is formed mainly by volcanic rocks: basalts, tuffs, and andesites of Maastrichtian age. In other places, deep-water cherts and shales prevail, intermingling with pillow basalts (Zonenshain et al, 1990). Volcanic activity in the Median Ridge occurred mainly in pre-Quaternary time and at present low fumarole activity is limited to its tallest volcano, the Ilchinskaya Sopka (3621 m). In the north, volcanic relief combines with glacial and periglacial forms associated with the late Pleistocene glaciation. Two glacial phases are distinguished although the sequence of glaciation is still subject to controversy (Ananyev et al., 1993). Although moraines, till, and fluvio-glacial deposits of the earlier phase are poorly preserved, the extent of their distribution testifies to the extensive nature of the first phase. In the northern part of the Median Ridge, glaciation was of a reticulated type while in other regions it was of a mountain valley nature and only locally did valley glaciers descend into the foothills. Landiorms (e.g., end moraines, kames, and roches moutonnees) associated with the later phase are better preserved. The status of the two glacial events and the nature of the warm interval are still debated because of a notable lack of dates for sediments of the warm interval. Pollen analysis has shown that Betula-Larix forests with an admixture of Picea developed between 39 and 31 Ka BP on the West Kamchatka lowland pointing at a warmer climate than now (Noveishie otlozheniya, 1978). However, the biotic history of the late Pleistocene warm interval has been poorly studied and requires further investigation. The age of the second phase has been reliably established as between 21 and 10 Ka BP from sediments collected in the foothills of the Klyuchevsky volcanic massif (Kraevaya et al., 1983). Skeletal remains of mammoth found immediately under the till layer pointed at the lower boundary while a relict soil layer overlaying the till and buried under pyroclastic sediments indicated the beginning of the interglacial. The second phase of the late Pleistocene glaciation in Kamchatka may be correlated with the late Valday glaciation on the East European plain and the Sartan glaciation in Siberia. Although glaciation was extensive, its type and spatial extent were controlled by the distribution of precipitation (which is in turn controlled by topography) rather than absolute height. This resulted in a non-uniform distribution of the ice. The northern Median Ridge was the most extensively glaciated region in Kamchatka. In the northern part of the eastern macroslope, open to the moisture-laiden flow, only few watersheds were free of ice which descended on to the then exposed shelf forming a piedmont glacier. By contrast, south of the Shiveluch volcano, where the penetration of the easterly flow is limited by the Eastern Ridge, glaciation was markedly less extensive. Over 50 per cent of the modern ice of Kamchatka, which in total occupies 870 km², is concentrated in the northern Median Ridge. The snow line has a low position (about 1000 m a.s.l.) as a result of high humidity and cool summers. Glaciers usually cap the tallest summits, descending from the top in several streams which give the glaciers a characteristic star-like shape. Similar to many other regions, the Kamchatka glaciers are currently in a stage of retreat. Studies of glaciers of the volcanoes of the Tolbachic, Klyuchevsky, and Avachinsky groups (Central Kamchatka valley and the Eastern Volcanic plateau) have shown that the modern position of the termini is 100-200 m above those observed during the periods of maximum glacial advance in the 1690s, 1850-70 and 1910-20 (Solomina et al., 1995). Volcanic activity has short-term effects on glacial regime: not only does ice melt because of the volcanic heat but short-term advances also occur due to the low atmospheric transparency and lower temperatures that follow volcanic eruptions (Solomina et al., 1995).

The Central Kamchatka valley is a 50-80 km wide graben that separates the Median Ridge and the Eastern Ridge. The valley is constricted by the two ridges in the south, widening to the north where its relief becomes almost level. It contains the largest river of the peninsula, the Kamchatka (720 km in length). It was a water basin as recently as the early Pleistocene and at present it is predominantly filled with Cenozoic marine deposits overlain by thick layers of Quaternary and modern andesitic and basaltic lavas as well as fluvioglacial and alluvial sediments. The main centres of the Pleistocene glaciations were the Shiveluch volcano and volcanoes of the Klyuchevsky and Tolbachik groups. Their slopes were covered with ice which descended well into the valley and vast fluvioglacial plains were formed on ice retreat. The alluvial plains and terraces of the Kamchatka are of a younger Holocene age.

The average elevations in the Eastern Ridge, extending from the south of the peninsula to the Ozerny Bay, are about 1300-1500 m and its highest point is the Kizimen Volcano (2485 m). The ridge has a complex accretional structure comprising three main tectonic units and its topography is formed by a number of ridges and volcanic plateaus. The core of the ridge is formed by Cretaceous rocks, and the spurs are composed pf Paleogene sandy-shales and volcanic rocks. Across vast areas, bedrocks are overlain by thick Quaternary andesitic and basaltic lavas. Evidence of late Pleistocene glaciation is widespread and indicates that glaciers descended into the sea. Contemporary glaciation is mainly limited to the Kronotsky peninsula where glaciers descend from Mount Otdelnaya to an altitude of 500 m a.s.l.

The Eastern Volcanic plateau is a 700-900 m high hilly terrain with volcanic cones set upon it. Out of 28 active volcanoes of Kamchatka, 22 are located here. The plateau is formed by pyroclastic material: thick deposits of lava, tuff, volcanic sand, and ash. In the late Pleistocene, volcanoes of the Avachinsky group as well as the mountains in the upper portion of the Avach river were extensively glaciated. Another centre of glaciation was located further south: the calderas of the Gorely and Ksudach as well as the Pauzhetsk depression were filled with ice which descended along the valleys, forming large valley glaciers. At present, the snow line is positioned at about 1500-1600 m. Summits of many volcanoes are covered with snow while calderas are often filled with ice.

Volcanism as a Landscape-forming Factor

Active volcanism is one of the major factors that sculptures the landscapes of Kamchatka (Plate 18.1), which is mainly formed by volcanic rocks such as andesites, basalts, and tuffs.

Plate 18.1 Volcanoes of Kamchatka

The volume of eruption products generated over the last 200 000 years totals 4200 km³ with the Quaternary effusives covering 42 per cent of the peninsula and landforms of volcanic origin (e.g., lava plateaux, volcanic cones, ancient calderas, and volcanic ridges) dominating its relief (Deistvuyushie vulkany Kamchatki, 1991; Kozhemyaka, 1994). Research into the history of volcanism began in Kamchatka in the 1960s when new techniques, including radiocarbon dating and tephrochronology, were developed. At present a detailed account of the ages of most calderas, large explosive craters, and recently active volcanoes is available largely through the work by Melekestsev and Braitseva of the Institute of Volcanic Geology and Geochemistry in Petropavlovsk Kamchatsky. Holocene volcanic activity is the best researched while information on pre-Holocene eruptions is more limited. This is because the pre-Holocene soil, peat, and pyroclastic layers were largely destroyed both in Kamchatka and the Kuril islands during the late Pleistocene glaciation, while deposits accumulated under cold conditions are extremely poor in organic matter. Potassium-argon dating is of limited utility due to the low concentrations of potassium in the Kuril-Kamchatka rocks (Braitseva et al, 1995b). A number of periods of enhanced volcanism occurred in the Quaternary with the intensity and scale of events declining from the late Pleistocene to the present (Melekestsev et al., 1988). A period of catastrophic volcanic eruptions occurred in the late Pleistocene, between 45-39 and 30-25 Ka BP, when the character of volcanism varied across the region. Acid volcanism dominated in southern and eastern Kamchatka where the Kuril Lake, Opala, Gorely, Krashenninikov and Uzon and Bolshoy and Maly Semyachik calderas and the surrounding ignimbrite and pumice strata were formed, respectively, about 39-42 and 25-30 Ka BP (Braitseva et al., 1995a, b). By contrast, basaltic volcanism dominated the Median Ridge, being also notable on the Eastern Volcanic plateau (e.g., in the Kluchevsky and Avachinsky groups). Thick tephra-rich layers, dated to the late Pleistocene, and found in the bottom sediments in the north-western Pacific at a distance of 1000 km off the eastern Kamchatka coast and near the city of Magadan, testify to the intensity of the eruptions (Melekestsev et al., 1991). Volcanic eruptions were an important source of sediment accumulating in the Central Kamchatka valley. The strata of loamy sands, reaching 40-50 m in thickness, are formed largely of weathered pyroclastic material and contain numerous layers of tephra. The rate of sedimentation was extremely high reaching 1-3 m per 1000 years, partly due to the large amount of pyroclastics and partly to the high erosion rates resulting from the continuing uplift of the mountains. Another period of enhanced volcanic activity followed in the early Holocene between 9.5 and 7 Ka BP. According to Melekestsev et al. (1988), volcanism of this period was weaker than during the preceding ones as indicated by a smaller amount of pyroclastics, the formation of smaller calderas, and a notable lack of ignimbrites. However, a paroxism of explosive acid volcanism between 7.8 and 7.5 Ka BP produced some of the major acidity peaks in the Greenland ice cores and may have contributed to climatic cooling (Zielinski et al., 1994). One more period of synchronous upsurge of volcanic activity was 1800-1300 years ago. Several powerful explosive eruptions of the Shiveluch took place, basalts started to erupt in the Tolbachik region and several stratovolcanoes began to form (Braitseva et al., 1995a, b). While the activity of volcanoes of late Pleistocene age is diminishing, those that started to form at the end of the late Pleistocene and in the Holocene have remained extremely active. At present, almost the entire territory of Kamchatka is affected by the fallout of volcanic material which are most intensive in the east and in the south. Ashfalls periodically interrupt the soil-forming process and widespread in Kamchatka are stratified ochre volcanic soils. Ashfalls have a fertilizing effect and improve drainage. Rich vegetation, otherwise not typical of the region, often develops on volcanic soils despite the severe climate (Sokolov, 1973; Manko and Sidelnikov, 1989).

The widespread occurrence of porous volcanic rocks preconditions the efficient infiltration of precipitation and the development of extensive underground drainage. Spring floods are rare and occur mainly when enough volcanic ash is precipitated to cause an exceptionally rapid thawing of snow. Widespread are lakes of volcanic origin which either develop in the old volcanic craters or are formed by lava dams. These differ in size, depth, temperature, and chemical composition. The two largest lakes, Kronotskoe (212 km², 148 m in depth) and Kuril (76 km²; 306 m) are old volcanic craters filled with water. Situated near active volcanoes of the Kronotskaya Sopka (3528 m) and the Ilchinskaya Sopka (1578 m), they are fed by numerous mountainous streams originating in hot springs and despite cold winters some outlets of the lakes do not freeze over.

The largest volcanic centre is the Klyuchevsky volcanic massif which comprises 20 volcanic formations and is of a young age (about 800 Ka BP). The massif occupies an area of 7500 km² with the total volume of volcanic rocks of about 8000 km³. Volcanism is more intense than anywhere else in the region: on average, pyroclastic material is generated at a rate of about 0.01 km³a^-1 (Kozhemyaka, 1995). The tallest and one of the most active volcanoes of Kamchatka, the Klyuchevskaya Sopka (4750 m), belongs to the massif. The Klychevskaya Sopka is glaciated, with a vast glacier descending to a height of 1500 m along the eastern slope. Typical of the glacier are alternating layers of ice, volcanic ash, and debris. The main features of the local landscape are ice, young lava streams, and scoria-ash deserts. Other volcanic cones on the Pacific side of Kamchatka (e.g., the Shiveluch) carry glaciers. However, volcanic activity brings about the rapid melting of snow and while Kamchatka would seem to have conditions ideal for the development of glaciers, relatively little snow and ice accumulate annually except in the craters of extinct volcanoes. Volcanic and fumarole activity changes glacial topography and rearranges the distribution of ice and often glaciers do not have permanent channels. Volcanic ash, accumulating on the surface of the glaciers, changes their radiation balance, promoting melting.

More than 150 groups of hot springs are known in Kamchatka (Gidrotermalnye sistemy, 1976). These are concentrated mainly in the Eastern Volcanic plateau and correspond to centres of acidic volcanism which developed here in the late Pleistocene. The largest formation is the Uzon-Geyser tectonic-volcanic depression which represents an oval-shaped caldera, 15 km x 7.5 km. Water temperatures in thermal springs and lakes range between 38°C and 97°C. The largest in the Kamchatka geothermal power system with the combined heat flow of 140 000 kcal s^-1 is maintained by the Uzon-Geyser. Not only does the strato-volcano Uzon formed about 40 Ka BP have a large caldera, but it is also characterized by a unique variety of geothermal features including fumaroles, thermal mineral springs, lakes, mud kettles, and mini-mud volcanoes. Lakes occupy craters reaching 100-150 m in diameter and 45 m in depth and water temperatures near the bottom of such lakes may reach 130°C. In all, over 500 various geothermal features are found in this relatively small area (Belousov et al., 1983). Under the geothermal conditions, rocks transform into speckled clays. The ongoing formation of ores occurs near the discharge centres of mineral thermal waters enriched with arsenic, zinc, copper, antimony, and mercury (Karpov, 1988).

Another remarkable place is the Geyser Valley which, as its name suggests, has a high concentration of geysers (19 geysers and 9 pulsing thermal springs occur across a 5 km distance). The Geyser Valley is associated with a system of faults and fissures which reach deep hydrothermal aquifers (Goleva, 1993; Ivanov et al., 1995) (Figure 18.6).

Fig. 18.6 Model of a hydrothermal system

The largest geyser, the Velikan (which name means 'a giant') has a pipe of 3 x 1.5 m. Spouts of boiling water reach 35m while vapour is ejected to a height of 250 m. Not only spouting geysers but also pulsing thermal springs, vapour jet sources, and mud geysers occur in the valley. Depending on the thermal water discharge regime which varies in time, geysers can act as pulsating springs and vice versa (Sugrobov and Sugrobova, 1990). Under the influence of boiling water and vapour enriched with various mineral elements the original rocks are transformed into geyserites (or sinters).

Ecology

Although the isolation of Kamchatka should have resulted in a strongly endemic biota, its flora and fauna are neither original nor rich, first, because of the severe climatic conditions, and second, because of the frequent catastrophic volcanic eruptions. There are only 900 species of higher plants represented mainly by a circumpolar flora. For comparison, there are about 2000 species in the Ural mountains and 6000 species in the Caucasus which occupy approximately the same territory (Makunina, 1969).

The large extent of Kamchatka from north to south results in latitudinal zonation. However, this is complicated by complex terrain and vertical differentiation is prominent in the vegetation structure. About 30 per cent of the peninsula is forested and another 30 per cent is covered by Finns pumila and Alnus kamtschatica thickets, while the rest is swamped or occupied by alpine tundra and volcanic landscapes. A vast tundra plain occurs in the extreme north of Kamchatka and on the western coastal plain tundra communities reach the southernmost extremity of the peninsula (52°N). Here, oligotrophic sphagnum bogs form a 30-50 km wide continuous belt.

The basic vertical vegetation sequence is simple: forests occupy the lowest 600-880 m; Pinuspumila and Alnus kamtschatica thickets occur above, extending to an altitude of 900-1000 m to be succeeded by alpine meadows, mountain tundra, and volcanic landscapes (Bykasov, 1985). However, the vertical distribution of vegetation strongly depends on climate and because the climates of the eastern coast and the Central Kamchatka valley are different, more specific models have been proposed for each of these regions. Thus, typical of the Central Kamchatka valley, which has a relatively dry climate, are coniferous forests of the taiga type in which Picea abies and Larix cajanderi are the main forest-forming species (Efremov, 1973; Manko and Vorochilov, 1978). At an altitude of 300-350 m, these are succeeded by forests composed of Betula ermanii (rock birch) which develops from the base to the thicket belt on the humid and windy eastern coast. The rock birch forests are perhaps the most distinguishing feature of Kamchatka's vegetation. Characteristic of such forests is a rich herbaceous tier dominated by Calamagrostis langsdorffti. The river and forest meadows are typical and account for a high proportion of the forest zone. These are dominated by tall grasses such as Filipendula kamtschatica, Cacalia hastata, and Heracleum lanatum which reach heights of 3.5-4 m under conditions of optimum moisture supply (Stepanova, 1985). Thickets of shrubs and small trees form a distinct altitudinal belt. These always consist of one species of shrub, usually either Pinus pumila (in sunnier and drier habitats) or Alnus kamtschatica (in shady and moist sites) and less often Sorbus sambucifolia. Despite many tall summits, the subalpine and alpine zones are limited in extent because of the narrowness of the mountain crests, sharpness of volcanic cones, and the inability of volcanic debris to support vegetation. The subalpine tall-grass meadows, dominated by Heracleum dulce, Lilium avenaceum, Aconitum flschery, Iris setose, and Fritillaria kamtschatcensis, develop on flat watersheds and gentle slopes. The alpine zone is represented by alpine meadow and heath tundra communities. Alpine tundra communities develop in drier habitats such as those on steep slopes or porous volcanic rocks (Nescha-taev and Chramkov, 1994). Typical of such habitats are Rhododendron aureum, R. kamtschaticum, Salix polaris, Vaccinium vitis-idaea, and V. uliginosum.

Very unusual communities of thermophilic plants develop in geothermal areas where the soil surface temperature reaches 80-90°C. Only a very few plants can adapt to such conditions including Ophioglossum thermale, Fimbristylis ochotensis, Lycopus uniflorus, and Stachys baicalensis (Rassohina and Chernyagina, 1982).

A small but remarkable vegetation community is that of an Abies gracilis grove which occupies an area of 20 hectares on the eastern coast (Neshataeva and Fet, 1994). Although this grove was first described by Krasheninnikov who led the first geographical expedition to Kamchatka in 1755, its origin is still disputed. It has been suggested that Abies gracilis may be a Tertiary relict (Naumenko, 1984) while other hypotheses suggest that it is a relatively young Holocene formation (Skiba, 1975) possibly planted by indigenous tribes for worship (Turkov, 1967).

The fauna of Kamchatka resembles that of an island. Because the peninsula is separated from the mainland by the treeless Parapolsky valley, there are no typical taiga species (e.g., elk, musk deer, polecat, lynx). Brown bear is the most common species and the bears of Kamchatka are among the largest, reaching a weight of 650-700 kg (Plate 18.2).

Plate 18.2 A brown bear in the Geyser Valley, Kamchatka

In the mid-1960s, their population reached 20 000 but it has been since reduced to under 8000 (Gordienko and Radnaeva, 1994). There are no more than 200 bird species and no reptiles.

Environmental Management and Nature Protection

Most of Kamchatka does not experience strong anthropogenic pressure. This is mainly limited to two areas: the Petropavlovsk-Elizovo agglomeration where 80 per cent of Kamchatka's industrial potential and 70 per cent of population are concentrated, and the Central Kamchatka valley which has natural conditions suitable for commercial agriculture and forestry. Although at present the cities of Kamchatka are far from being pollution-free, maintaining high environmental quality in the future is feasible because there is no need to burn fossil fuel. Geothermal resources guarantee virtually unlimited supplies of energy. Thus, a geothermal power with a potential total capacity of 3 x 10s watts spares the necessity of burning a million tonnes of coal per year (Karpov, 1994). The first Pauzhetskaya geothermal power plant has been operating since 1967 and another plant is currently under construction. It is not unusual for farmers to use geothermal water.

The pristine condition of the environment offers great opportunities for the development of ecotourism. There are a number of protected areas of different types which account for 27 per cent of the total area (Santalov, 1995). In 1996, a network of protected areas 'Volcanoes of Kamchatka' was included in the UNESCO list of World Nature Heritage.

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