Zonal Vegetation Types

The Arctic Area of Polar Deserts

On the territory of Russian Far East only Wrangell and Gerald Islands are related to the zone of Arctic Deserts. The lack of closed vegetation cover is characteristic for the zone. Large areas on the islands are represented by taluses and rock outcrops. The crustose and foliose lichens (the species of genera Gyrophora, Lecidea, Rhizocarpon) are most abundant on the stony substrate. On the sites with accumulation of fine soil the fruticose lichens from genera Alectoria, Cetraria, Cladonia and mosses Andraea papillosa, Pogonatum capillare, Rhacomitrium lanuginosum and Tetraplodon mnioides form the sparse cover. The vascular plants are represented by Douglasia ochotensis, Artemisia glomerata, Papaver polare, Saussurea tilesii, Saxifraga funstonii etc. The bryophytes and flowering plants are scattered and not numerous.

The Arctic Area of Tundra

The coast of the Arctic Ocean and all peninsula Chukotka north of 59°N are covered by tundra vegetation. The Tundra Zone is subdivided into 2 subzones: typical Arctic tundra occurs along the coast of Ice Ocean and lichen tundra is the main zonal vegetation on Chukotka peninsula and the lower part of Anadyr River basin. Far Eastern sectors of Arctic Polar Desert Area and Arctic Tundra Area are differed from the rest of circum-Arctic zone by presence of so-called Beringian plant species, which are also common to Alaskan and Eastern Canadian sectors of Arctic zone.

The specific traits of tundra vegetation are: one-layer closed vegetation cover; predominance of perennial plants; high importance of dwarf shrubs; high importance of mosses and lichens; the lack of shrubs and trees. Most of typical tundra plants have the buds at a height lower than 20-30 cm above ground and presumably vegetative reproduction. All tundra plants are adapted to the short vegetative season and to the long daytime.

Tundra communities vary in composition depending on edaphic and climatic features of a site. The regions lying along the coast of the Northern Ocean are characterized by predominance of sedge and hearth tundra communities with Carex spp., Eriophorum vaginatum, Vaccinium uliginosum, Betula exilis and leafy mosses. On Chukotka peninsula sedge tundra communities are also important, but the role of lichen tundra communities with Cladina spp. and some ericatious dwarf shrubs increases.

Subarctic zone: Beringian Woodland Area

The Area is characterized by a dominance of dwarf-trees: the conifer Pinus pumila and the broadleaved Alnus fruticosa s.l. This vegetation is widely distributed in the basins of Anadyr and Penzhina Rivers, on the Koriakskiy mountain range, northern half of Kamchatka, southernmost part of Kamchatka (Lopatka Cape) and Commander and Northern Kuril Islands. In continental regions (Kolyma River) the zone of dwarf-pine is not expressed. Arctic Zone appears to have a border with the Boreal Larch zone there. Kolesnikov (1955) proposed the presence of more or less extensive tundra patches on plakors (zonal sites) to be a criterion for distinguishing the Beringian Woodland Area. Taking into account this criterion the southern border of Area goes due south along the coast of the Sea of Okhotsk till Magadan including northern part of Koni peninsula. Although the Beringian Woodland Area is situated only in the submaritime, maritime and suboceanic sectors, the vegetation is gradually changed from Pinus pumila thickets as a dominant zonal type in the inland areas to the Alnus fruticosa thickets as a dominant type in the coastal regions. Larix dahurica as the sole trees are stable component of vegetation, but its portion increases towards inland regions. In river valleys and on the southern slopes it can form small forest patches. On the areas with permafrost the mires with Carex appendiculata, Eriophorum spp. and Sphagnum spp. are widely distributed. In the river valleys there are small patches of forests dominated by Populus suaveolens and Chosenia arbutifolia in combination with wet grass meadows.

Boreal zone: Eastern Siberian Larch Area

The Area is one of the biggest homogenous phytogeographical contours in whole circum-boreal zone. It stretches from the southern boundary of tundra zone in continental regions and Woodlands in maritime regions reaching the coast of the Sea of Okhotsk in the northern boreal zone to the Amur River basin on the south. The larch forests go west to Yenisey River, where on the same latitudes they are changed by spruce (Picea obovata) forests. The main feature of the Area is the dominance of Larix dahurica s.l. on the zonal sites.

Despite a great variety of larch communities in ecological regimes and climatic conditions, the species composition of communities demonstrates outstanding homogeneity within all wide range from south to north and from the west to east. A number of seral species, such as Betula platyphylla, Populus suaveolens and Alnus hirsuta may accompany the Larix dahurica on zonal sites. River valleys are occupied by Populus suaveolens, Salix udensis, Salix rorida and Chosenia arbutifolia forests.

The dominance of shade intolerant larch on such a great territory is caused by extremely severe climatic conditions and permafrost, which can be tolerated only by Larix dahurica.

Boreal zone: Eastern Okhotian Dark-Conifer Area

The area lies in the middle of Kamchatka peninsula between Sredinniy and Vostochniy Mt. Ranges. Larch and spruce (Picea ajanensis) form the conifer forest here in the specific submaritime local climate, which became possible due to mountain protection from the influence of both Okhotian and Pacific Ocean air masses. The Area is surrounded by Beringian woodlands with Alnus fruticosa as a dominant on the north and by specific stone birch (Betula ermanii) forests in combination tall forb meadows from the south, east and west sides.

Spruce and larch forests represent zonal vegetation in the area. Despite spruce doesn't have the northernmost part of its range there, climatically they may be considered as the coldest in the geographical range of Picea ajanensis. The spruce forests of the area are characterized by the predominance of circum-boreal of Pacific-boreal species in the all layers.

Larix dahurica forests in this area dominate mainly on sites with intensive disturbance regimes caused by fires or volcanic activity or in the areas with a local climate of subcontinental type lying on the south of the "conifer island". Structure and floristic composition of the larch forests is similar to those of Eastern Siberia and a continental part of the Russian Far East.

Populus suaveolens, Chosenia arbutifolia and Salix udensis forests represent the valley vegetation of the Area. Along the Kamchatka River the grass meadows are typical for the floodplains.

Boreal zone: Northern Pacific Meadow-Stonebirch Area

Stone birch (Betula ermanii) forms forests on zonal sites in southern half of Kamchatka peninsula and on the middle Kuril Islands (Iturup, Urup) in a conditions of severe sub-oceanic climate with cold summers and mild winters with near equally distribution of precipitation between the seasons (Figure 8). On the places of accumulation of snow, another important for zone vegetation type, the tall forb meadow is developed. Both vegetation types characterize the cold and wet sub-oceanic climate within the northern portion of boreal zone.

Principal and most widespread community type in the Area is stone-birch forest with tall forbs (Senecio cannabifolius, Filipendula camtschatica). On the well-drained sites the portion of mesophytic forbs (Geranium erianthum, Saussurea pseudotilesii, Artemisia opulenta) is increased. On the wetlands the tall forbs in combination with Calamagrostis purpurea form the subalpine-like meadows on the extensive areas mostly in southern and eastern portion of the Area.

Populus suaveolens, Chosenia arbutifolia and Salix udensis forests represent the valley vegetation. The characteristic features of them are a dominance of tall forbs in the herb layer.

Boreal zone: Western-Okhotian Dark-Conifer Area

Picea ajanensis is a dominant species in the Western-Okhotian Dark-Conifer Area. This species is distributed in the conditions of submaritime and maritime climate in the middle and southern subzones of boreal zone. The range of spruce forests within this Area covers the southern part of Dzhugdzhur Mt. Range, eastern part of Stanovoy Mt. Range, the country between the rivers Amur and Uda, Northern portion of Sikhote-Alin Mt. Range, all Sakhalin Island, Iturup Island (Southern Kurils) and Pacific sector of Hokkaido Island. On the north and west the Area is bordering with Eastern Siberian Larch Area. On the south it contacts with Northern Temperate Broadleaf - Korean Pine Area.

The main vegetation type in the Area is pure in the northern part of range or mixed with firs (Abies nephrolepis and closed species Abies sachalinensis) in the southern part of range spruce forests. However, Abies sachalinensis can form pure stands in the southern portion of Sakhalin Island and on the southern Kuril Islands. There are several other species of spruce, which forms communities within the Area. Picea koraiensis (the species closed to Picea obovata and Picea abies) forms stands on the well-drained river valleys in continental part of spruce range and Picea glehnii forms stands on the wetlands in few points of southernmost Sakhalin and on Kunashir, Shikotan and Iturup Islands (southern Kurils).

Extensive fires decreased the area of modern distribution of spruce forests, replacing them by the secondary larch forests. Larch forests are the second important vegetation formation in the Area. In a condition of presence of sources of dissemination and absence of wildfires spruce can replace larch on zonal sites in 100-300 years after fire.

In river valleys the basic vegetation types are larch forests and woodlands, Populus suaveolens and Populus maximowiczii forests, Chosenia arbutifolia, Salix udensis and Salix rorida forests. On the lowest parts of valleys the grass meadows with Calamagrostis purpurea are developed. In the depressions with cool air drainage on the sites with the permafrost and on the poorly drained sites the sedge (Carex appendiculata) and sphagnum bogs are widely distributed across the zone.

Northern temperate zone: Daurian Broadleaved forest area

The most of area lies in the northeast China reaching on the west the northeast Mongolia. On the territory of Russian Far East in appeared in upper part Amur River basin called Dauria and in the basin of Lake Khanka. These areas since mid centuries were strongly influenced by human activity, what partly explains the actual state of vegetation in the area. Modern vegetation cover contains meadows, bogs and forests in near equal proportions. Most of meadows and part of bogs after melioration were transformed in agricultural lands. Basic forest type is Mongolian oak forming pure or mixed with Betula davurica stands. All components of forest communities are drought tolerant and fire resistant. Fire is the most important factor influencing the natural selection in the oak communities.

Meadows in the zone are distributed on well-drained insolated slopes (steppose meadows) and in lowlands next to the boggy vegetation. Specific feature of steppose meadows is the presence of xeric and xero-mesic herbs and grasses (Cleistogenes kitagawae, Stipa baicalensis, Arundinella anomala, different species of Astragalus, Galium, Scabiosa, Allium, Artemisia etc.). The mesic and hygric meadows dominated by Miscanthus sacchariflorus, Calamagrostis langsdorffii occur on the lowlands. On the hill slopes and ridges Pinus densiflora (near Lake Hanka), Pinus sylvestris (in upper Amur), Armeniaca sibirica, Ulmus macrocarpa form small patchy stands.

Northern temperate zone: Manchurian Broadleaved - Conifer Area

The area lies on the spurs of Sikhote-Alin Mt. range and on the southerly spurs of Lesser Hingan, Bureinskiy and Badzhalskiy Mt. ranges. Main vegetation type is the broadleaved - Korean pine forests dominated by Pinus koraiensis and a number of broadleaved species: Tilia amurensis, Tilia mandshurica, Fraxinus mandshurica, Quercus mongolica, Betula costata, Abies holophylla (only south from 44th latitude), Kalopanax septemlobus, Phellodendron amurense, Ulmus japonica. Normally in a forest community the number of tree dominants is 3-5 species. On elevation of 600-800 m above sea level, the temperate communities may be enriched by boreal dominants Picea ajanensis and Abies nephrolepis.

Other vegetation types distributed in the area are broadleaved valley forests from Ulmus japonica and Fraxinus mandshurica on the old and stable parts of river valleys, Populus maximowiczii and Populus koreana (in fact close species) on the younger parts of river valleys and Chosenia arbutifolia on the fresh alluvial deposits. The poorly drained parts of Ussuri valley are occupied by grass meadows.

The portion of old-growth forests in the area has been drastically decreased in 20th century as a result of forest exploitation and fires. The secondary forests are represented by mixed broadleaved forests with no conifers, Betula platyphylla and Populus tremula forests, and Quercus mongolica forests with no conifers depending on ecological features of site and kind of damaging factor.

Northern temperate zone: Northern Japanese Broadleaved - Conifer Area

The temperate vegetation in a condition of suboceanic climate on southern Sakhalin, southernmost Kurils (Kunashir, Shikotan, Zelioniy, Tanfilieva) differs from the temperate vegetation on continent by dominants and species composition formed under influence of Japanese flora. Main vegetation type is mixed Abies sachalinensis - Quercus crispula forests with Sasa (fruticose grass relative to bamboo). Most part of the area lies on Hokkaido Island north of Kuromatsunai Lowlands where it borders with the area of Fagus crenata forests. The zonal vegetation in the area is mixed Abies sachalinensis - Quercus crispula forest with an admixture of broadleaved species: Kalopanax septemlobus, Tilia maximowicziana, Fraxinus mandshurica etc.

The moist lowlands are occupied by wet meadows from Carex thunbergii, Calamagrostis langsdorffii, and Myrica tomentosa fringed by Alnus japonica - Fraxinus mandshurica forests. Ulmus japonica and Fraxinus mandshurica form forests with Cercidophyllum japonicum in the second tree stratum and Lysichiton camtschatcense, Symplocarpus renifolius, Trillium camschatcense and Dryopteris crassirhizoma in the understory.

Vertical vegetation zones

Russian Far East is montane area. Mountain systems vary greatly in origin, age, height, modern geological processes, and orientation of the basic mountain ranges. The change of climate along the elevation gradient causes the change in vegetation. Traditionally, in Russian geobotany a vegetation zone formed by climate differentiation with elevation is considered as vertical zone, or belt, and analyzed as a secondary zonation within a frame of horizontal zones (Krylov 1984). The areas described are characterized by a definite sequence of vertical zones and by certain altitudinal position of each zone. Last may vary depending on a number of geomorphologic factors, among of which the general exposition has most expressed effect on an altitude of a zone, making it higher on southerly and lower on northerly slopes.

General sequence of vertical zones in southern part of Russian Far East in submaritime sector repeats the sequence of horizontal zonality, appearing from bottom to top as an alternation of broad-leaved - Korean pine forests, fir-spruce forests, Betula ermanii forests, dwarf-pine thickets and alpine tundra. Vertical belt in most cases may be considered as an analogue of horizontal zone by its physiognomy as well as species composition. However, depending on a region, the species composition of vertical zone may be enriched by the species from the upper or lower lying vertical zone.