taiga(redirected from Boreal forests)
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taiga(tī`gə), northern coniferous-forest belt of Eurasia, bordered on the north by the treeless tundra and on the south by the steppe. This vast belt, comprising about one third of the forest land of the world, extends south from the tundra to about lat. 62°N in Norway, Sweden, and Finland, but dips still farther south to about lat. 53°N in the Urals. It extends through northern European Russia across the Ural Mountains and over most of Siberia. It has a continental climate, with long, severe winters of 6 or 7 months. Thawing occurs during late April or early May, and the growing season is short. The mean average summer temperatures are fairly high, but there are night frosts. Podzols are the soils of this zone. Only the hardier cereals and roots, such as barley, oats, and potatoes, can be cultivated. The principal species of trees are cedar, pine, spruce, larch, birch, and aspen. The taiga has many swampy areas formed during the spring.
A zone of forest vegetation encircling the Northern Hemisphere between the arctic-subarctic tundras in the north and the steppes, hardwood forests, and prairies in the south. The chief characteristic of the taiga is the prevalence of forests dominated by conifers. The dominant trees are particular species of spruce, pine, fir, and larch. Other conifers, such as hemlock, white cedar, and juniper, occur locally, and the broad-leaved deciduous trees, birch and poplar, are common associates in the southern taiga regions. Taiga is a Siberian word, equivalent to “boreal forest.” See Tundra
The northern and southern boundaries of the taiga are determined by climatic factors, of which temperature is most important. However, aridity controls the forest-steppe boundary in central Canada and western Siberia. In the taiga the average temperature in the warmest month, July, is greater than 50°F (10°C), distinguishing it from the forest-tundra and tundra to the north; however, less than four of the summer months have averages above 50°F (10°C), in contrast to the summers of the deciduous forest further south, which are longer and warmer. Taiga winters are long, snowy, and cold—the coldest month has an average temperature below 32°F (0°C). Permafrost occurs in the northern taiga. It is important to note that climate is as significant as vegetation in defining taiga. Thus, many of the world's conifer forests, such as those of the American Pacific Northwest, are excluded from the taiga by their high precipitation and mild winters.
a city under oblast jurisdiction in Kemerovo Oblast, RSFSR. Junction on the Trans-Siberian Railroad with a branch line to Tomsk, Asino, and Belyi lar. Population, 26,400 (1974). Taiga has food-processing, light-industry, and building-materials enterprises and enterprises serving railroad transportation. There is a railroad transportation technicum in the city.
coniferous forests of the northern temperate zone, consisting of boreal species of spruce, fir, larch, and pine, including nut pines, with some hardwood species. The transitional zone between the taiga and broad-leaved forests is called the subtaiga. The taiga has an average July temperature of 10°C–18°C. It has a relatively short frost-free period, cold winters, precipitation that exceeds evaporation, and a stable snow cover. The term “taiga” also designates one of the geographic subzones of the northern temperate zone. The taiga occupies enormous areas of northern Eurasia and North America, extending over large mountainous regions in northern Europe, Japan, and the Pacific coast of North America. In regions with a continental climate the taiga reaches far north; for example, in the Taimyr it is situated north of 72° N lat. In regions with an oceanic climate, however, it is situated at 42° N lat., for example, on Honshu Island, Japan.
The taiga is divided into northern, central, and southern zones. In the USSR these zones are most marked in the East European and Western Siberian plains. The taiga is also divided according to vegetation into dark-coniferous and light-coniferous zones. The dark-coniferous zone is characterized by spruce, fir, Siberian stone pine, and stone pine, while the light-coniferous zone features common pine, larch, and some American pine species.
Tree species harvested for timber form pure stands, for example, spruce and larch, and also mixed spruce-fir stands. The dark-coniferous forest, the most widespread and most typical of the taiga, grows on characteristic taiga soils, which are covered with mosses, lichens, or a layer of decaying pine needles. Dark-coniferous taiga species are shade-tolerant, since their needles are capable of photosynthesis with little sunlight. Because there is little light in the forest, taiga forests are sometimes completely lacking in underbrush. Shrub, subshrub, and herb species are few. Shrubs include juniper, honeysuckle, currant, and willow, while the most common subshrubs are whortleberry and mountain cranberry; Oxalis, Pyrola, and ferns predominate among the herbaceous plants. Despite the scarcity of species, shrubs, sub-shrubs, and herbaceous plants occur in dark-coniferous taiga forests in Eurasia and America.
Forests featuring green mosses, herbaceous shrubs, and dark-coniferous forests are distributed on the more fertile, loamy soils. In addition to dark-coniferous species, they include pine, birch, and occasionally larch. Southern regions of the European taiga belt have oak, linden, Norway maple, and European alder. As humidity decreases, the ground cover in associations of dark-coniferous taiga consists of sphagnum and other marsh mosses. In some regions, dark-coniferous forests are being replaced by sphagnum peat bogs, which are especially typical of the northern and central taiga. In southern areas of distribution, especially in the mountains and near ocean coasts, taiga vegetation has more varied species and more complex species combinations.
Eastern Siberia mainly features light-coniferous taiga, which, besides larch, has various other classes of associations. Larch forests are light, usually thin, and often have underbrush of dwarf stone pine, Rhododendron dahuricum, and scrub birch, and a developed herbaceous cover of varying composition. The principal tree species are Siberian larch and dahurian larch. The mountainous light-coniferous taiga of Transbaikalia is characterized by a mixture of stone pine and spruce. Light-coniferous taiga forests of common pine, which prefer light soils, are widespread in the northern and central taiga of Europe, the Trans-Ural region, and elsewhere.
Almost one-third of the USSR is situated in the taiga subzone and in high-altitude zones. In the mountains large taiga massifs are concentrated in Siberia and the Far East, in regions with the most continental climate. In Northern Europe, for example, the European part of the USSR, Finland, Sweden, and Norway, taiga forests, predominantly spruce, are influenced by sub-Atlantic climate. Substantial taiga massifs occupy the North Atlantic provinces of Canada, where black and blue-gray spruce and tamarack predominate. Mountainous taiga in Canada is confined to the Appalachians, which have black spruce, as well as red spruce and American species of fir.
On all continents the taiga forms the northern boundary of the forest zone. In Europe there is spruce on the boundary with the tundra. There is spruce and Siberian larch in Western Siberia and dahurian larch in Eastern Siberia. In North America the black spruce and tamarack form the northern boundary.
The taiga contains a significant concentration of commercial timber reserves. It also has valuable areas for commercial hunting and reindeer breeding.
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V. B. SOCHAVA