Russia's remaining territory, to the south and east, constitutes about one-fourth of the country's total area and is dominated by a complex series of high mountain systems. These include the Altai Mountains, which lie on the border with Kazakhstan and Mongolia; the area around Lake Baikal; the Stanovoy, Dzhugdzhur, Kolyma, Verkhoyansk, and
Chersky ranges in the east; and a volcanic zone on the Kamchatka Peninsula. The mountainous zone continues on narrow Sakhalin Island, which is separated from the Siberian mainland by the Tatar Strait.
The Russian landscape is known as much for its many and massive rivers as for its geological variety. Five main drainage basins may be distinguished: the Arctic, Pacific, Baltic, Black Sea, and Caspian. The Arctic basin is drained by three gigantic Siberian rivers: the Ob (2,268 miles [3,650 km]), the Yenisey (2,540 miles [4,090 km]), and the Lena (2,734 miles [4,400 km]). These rivers pro vide transport arteries from the interior to the Arctic sea route, although they are blocked by ice for long periods every year. South-eastern Siberia is drained by the large Amur system into the Pacific. The Dnieper, of which only the и pper reaches are in Russia, and the 1,162-mile-long (1,870 km) Don flow south to the Black Sea, and a small north-western section drains to the Baltic. The longest European river is the Volga. Rising in the Valdai Hills north-west of Moscow, it follows a course of 2,193 miles (3,530 km) to the Caspian Sea. Outranked only by the Siberian rivers, the Volga drains an area of 533,000 square miles (1,380,000 square km). The rivers of the Russian Plain, separated only by short overland portages and supplemented by several canals, have long been important transport arteries; indeed, the Volga system carries two-thirds of all Russian waterway traffic.
In addition to its numerous rivers, Russia contains some 2 million freshwater and saltwater lakes. In the European section the largest are Ladoga and Onega in the north-west, with surface areas of 6,830 (inclusive of islands) and 3,753 square miles (17,690 and 9,720 square km), respectively; others are Peipus, on the Estonian border, and the Rybinsk Reservoir on the Volga north of Moscow. What are described as narrow lakes, some 100 to 200 miles (160 to 320 km) long, are located behind barrages (dams) on the Don, Volga, and Kama. In Siberia similar artificial lakes are located on the upper Yenisey and its tributary the Angara, where the Bratsk Reservoir is among the world's largest. All of these are dwarfed by Lake Baikal, the largest body of fresh water in the world. Some 395 miles (636 km) long and with an average width of 30 miles (50 km), Baikal has a surface area of 12,200 square miles (31,500 square km) and a maximum depth of roughly 5,315 feet (1,620 metres). There are also innumerable smaller lakes found mainly in the ill- drained low-lying parts of the Russian and West Siberian plains, especially in their more northerly parts.
Russia's climate has historically been both a blessing - in times of war, most famously during Napoleon's 1812 invasion-and a heavy burden in terms of the difficulties it imposes on everyday life. The country's vast size and compact shape - the great bulk of the land is more than 250 miles (400 km) from the sea, while certain parts lie as much as 1,500 miles (2,400 km) away - produce a dominance of continental regimes. The great mountain barriers to the south and east shut out the potentially gentler influences from the Indian and Pacific oceans, and the absence of relief barriers on the western and northern sides leaves the country open to Atlantic and Arctic influences. All these factors, combined with the country's northerly latitude, mean that in effect there are only two seasons, winter and summer; spring and autumn are brief periods of rapid change from one extreme to the other. Harsh winter cold is characteristic of most of Russia: the frost-free period exceeds six months only in the North Caucasus, and varies with latitude from five to three months in the European section and from three to less than two months in Siberia. The world's lowest minimum January temperature outside Antarctica,-96 F (-71 C), was recorded at Oymyakon in eastern Siberia.
The main characteristics of precipitation throughout Russia are its modest to low total amounts and the pronounced summer maximum. Snow falls in virtually the entire country. The duration of snow cover varies with both latitude and altitude, ranging from 40 to 200 days across the Russian Plain and from 120 to 250 days in Siberia,
Climate, soils, vegetation, and animal life are closely interrelated, and variations among these within Russia form a series of broad latitudinal environmental belts. Moving roughly from north to south are zones of Arctic desert, tundra, taiga, mixed and deciduous forest, wooded steppe, and steppe.
Russia's Arctic desert is completely barren land, often ice- covered, with little or no vegetation. This area is confined to the islands of Franz Josef Land, much of the Novaya Zemlya and Severnaya Zemlya archipelagos, and the New Siberian Islands. Tundra, on the other hand, covers nearly one-tenth of Russian territory. This treeless, marshy plain occupies a narrow coastal belt in the extreme north of the European Plain, widening to a maximum of about 300 miles (500 km) in Siberia. Tundra soils are extremely poor, highly acidic, and frozen for much of the year. During the summer thaw, drainage is inhibited by the presence of permafrost beneath the thawed surface layer. Vegetation includes mosses, lichens, and stunted birch, larch, and spruce. Apart from reindeer, which are herded by the indigenous population, the main animal species are the Arctic foxes, musk oxen, beavers, lemmings, snowy owls, and ptarmigan.
South of the tundra, the vast taiga (boreal forest) zone is the largest of Russia's environmental regions, and the world's largest timber reserve. It occupies the Russian and West Siberian plains north of latitude 56 to 58 N, together with most of the territory east of the Yenisey River. In the western section forests of spruce and fir alternate with shrubs and grasses interspersed with pine on lighter soils; in the east these are present too, but the larch predominates. Only small areas have been cleared for agriculture, though coniferous forest is not continuous; there are large stands of birch, alder, and willow, and, in poorly drained areas, huge stretches of swamp and peat bog. The taiga is also rich in fur-bearing animals, such as sables, squirrels, martens, foxes, and ermines, and home to many elks, bears, muskrat, and wolves.
As conditions become warmer with decreasing latitude, deciduous species appear in greater numbers and eventually become dominant. Oak and spruce are the main trees, but there are also growths of ash, aspen, birch, elm, hornbeam, maple, and pine. The mixed and deciduous forest belt is widest along Russia's western border and narrows toward the Urals, but much of this zone has been cleared for agriculture, particularly in the European section. As a result, the wildlife is less plentiful, but roe deer, wolves, foxes, and squirrels are common.
Farther south still is the wooded steppe, which, as its name suggests, is transitional between the forest zone and the steppe proper. Forests of oak and other species (now largely cleared for agriculture) in the European section and birch and aspen across the West Siberian Plain alternate with areas of open grassland that become increasingly extensive toward the south. The wooded steppe eventually gives way to the true steppe, which occupies a belt some 200 miles (320 km) across and extends from southern Ukraine through northern Kazakhstan to the Altai. Russia has a relatively small share of the Eurasian Steppe, mainly in the North Caucasus and lower Volga regions, though pockets of wooded steppe and steppe also occur in basins among the mountains of southern Siberia. The natural steppe vegetation is characterized by turf grasses such as bunch-grass, fescue, bluegrass, and agropyron, with drought-resistant species common in the south. Much of the steppe vegetation, particularly in the west, has been replaced by grain cultivation, in no small part because of the region's chernozem, or black earth, a highly fertile soil of low acidity and high humus content. Typical rodents of the zone include the marmot and other such burrowing animals, and various mouse species. Skunks, foxes, and wolves are common, and antelope inhabit the south. The most common birds are bustards, eagles, kestrels, larks, and grey partridge.