Baikal ‑ a lake, invariably called the 'Pearl of Siberia', is a unique natural phenomenon of the Asian continent. The vast territory of its basin is subdivided into the Baikal country, including the hollow of the lake proper with mountain ranges fringing it, and Transbaikal ‑ a contrasting upland country embracing mainly the Selenga River basin. Lake Baikal, the majestic mountains, picturesque valleys, boundless expanses of taiga, steppes, lakes with crystal clear water ‑ all this constitutes a peculiar natural region situated on the borderline of the taiga Siberia and desert Central Asia, and on the longitudinal boundary of the Pacific and the Atlantic Oceans ‑ the major generators of climate in the whole of Eurasia. Therefore, represented here are all the main ecosystems of the Northern hemisphere with their unique vegetation and animal communities, with the scenery typical of the Pamir's highlands, Manchurian prairies, Jungar-turan deserts, European flatland meadows and forests, and even the towering summits of the Tibet and the Himalayans. And at the same time the long evolution has enriched the region's vegetation and Animal Kingdom with new species, occurring nowhere else in the world. Only in the waters of Lake Baikal there thrive about a thousand endemic species.
On the other hand, the striking diversity of live nature is the result of extraordinarily contrasting ecological conditions, the latter determined mainly by the complicated orography of the area, by the combination of high mountain ridges, undulating foothills and deep hollows between mountains, as well as by the extreme continental climate and island-like spreading of the permafrost. The vast expanses of the North Baikal country taiga with bare mountain-ridge summits, the dry steppes of the Selenga uplands, the luxuriant motley-grass Alpine meadows with dark coniferous forests covering the slopes of the Sayans and the Khamar-Daban and, last of all, the high Okhinsk elevation ‑ the stronghold surrounded by the taiga, sprinkled with patches of stony tundras, and Alpine wastelands (a real Tibet in miniature) ‑ these are the different faces of the beneficial Baikal land. One can meet here, existing side by side, plants and animals with strikingly different ecological demands. They form peculiar desert saltmarsh, frozen forest-meadow and Alpine tundra-steppe complexes. In the Transbaikal forest-steppe, existing for centuries side by side with each other, are desert and Alpine tundra plants, and quite nearby, one can see a young pine. Such are the contrasts of Transbaikal. All this determines the striking peculiarity of the Baikal region ecosystem, its steppes, meadows, forests, marshes, water-bodies and highlands, rich in unique species and endemic representatives of fauna and flora.
Transbaikal steppe is one of the most ancient and varied types of vegetation. Present here are species of plants and animals having historical connections with the East-Asian meadow, Middle Asian Alpine, East-European forest-steppe and even Central Asian desert-steppe ecosystems. Thus, one can see here not only colourful feather-grass steppes of European type, but severe Gobi landscapes with desert species of wormwood. The steppes stretch along all the altitudes, reaching the very highlands. They are forest-steppes covering the foothills, steppe clearings on sunlit slopes of the forest belt, and cold Alpine steppes at the tops of mountain ridges ‑ wonderful pastures for wild and domestic animals. But first and for most, they are invaluable as models of Central Asian steppes in the Baikal country taiga surroundings.
Lake basin forests are a complicated and most interesting phenomenon in the green cover of the Baikal necklace. They surpass in area all the rest ecosystems. Vast territories are under coniferous forests: spruce, fir, larch and pine. By far less various are small-leaved forests: birch and aspen. Alongside with their great economic significance, Baikal basin forests play a great role in stabilizing concomitant ecosystems, for they perform the main landscape-protecting and water-preserving functions. Baikal country forests present interest from historical and ecological points of view. Thus, found in the Khamar-Daban area are European and Manchurian tall-grass forests, which testifies to their complicated origin.
The Baikal country highland ecosystems form a unique world of their own where picturesquely combined are landscapes of the European Alps, of Siberian bare mountain summits, and of cold, dry Central Asian uplands. Alpine meadows, scree tundras, high altitudinal light forests and even Alpine steppes - such multi-component mountain landscape includes plants and animals wonderfully adapted to the environmental conditions. Alpine ecosystems regulate water balance of all the types of low-upland vegetation and ensure their ecological safety.
From the viewpoint of their landscape, big and small river valleys are the most diverse regions of Transbaikal, most beneficial for man. Dominating here are meadows, steppes, low-lying grass-marshes with their rich and unique vegetation and animal life. Flood-plain landscapes are difficult to imagine without river-bed willow forests, birch and poplar forests, as well as thickets of the powerful steppe grass ‑ derissun and pea tree on the terraces.
And last of all, Baikal proper, which contains about one fifth of the world's pure fresh water. In spite of the fact that Baikal is one of the most ancient of Eurasian lakes (it's more than 20 million years old), life in its depths is strikingly young. Dwelling there are 2630 species. Two thirds of them are endemic, i.e. they have originated in the lake and are not to be found anywhere else.
Everyone, who has ever been to the Baikal shores and on the mountain summits towering over the lake, is struck by the wonderful harmony in which Lake Baikal itself, the mountains surrounding it, the valleys of the rivers flowing into it have lived for millions of years. However, nowadays Baikal is suffering from an unprecedented in its power impact of man on all its systems. Water-bodies are being polluted, forests ‑ cut out, steppes and meadows ‑ degrading. Vast areas of land have been ploughed or destroyed by weathering. All this resulted in a considerable decrease of the biological diversity of its ecosystems. A great many species of plants and animals are on the verge of extinction. Many of the species, quite recently common in the Baikal country forests and steppes, have been referred to the rank of rare. And at the same time, as ecologists report, new species of animals and plants, not typical of Baikal nature, are coming to life. Thus, found in Baikal not long ago is an unusual 'stranger' ‑ green seaweed ‑ Canadian elodea. Not infrequent are such vulgar species of birds as the Northern starling, as well as such a shallow water fish as rotan. Ecologists all over the world are deeply concerned about the active intrusion of man into the most complicated natural systems of Baikal, for Lake Baikal has been pronounced the region of world's heritage.