Brief overview of natural conditions and vegetation cover of Altai-Sayan ecoregion
Altai-Sayan eco-region (ASER) is situated in the center of Asia and includes Altai (Altai mountain country), Sayan mts., ranges Kuznetsky Alatau and Salair, mountains of Tuva and Mongolia (between Mongolian Altai, Khangai and Hovsgol lake), and intermountain depressions. The territory covers over 1000000 km2 within Russia, Kazakhstan, China, and Mongolia. The region stretches 1600 km from the west to the east, and 1300 km from the north to the south. Altai-Sayan eco-region geographically coincide with Altai-Sayan mountain country. Altai-Sayan mountain country is the highest upland of Northern Asia. Its highest peaks are the two-headed Belukha (4506 and 4400 m) in Katunsky range and mountain knot Tawan-Bogdo-Ula (five divine summits with three highest peaks - 4374, 4360, and 3981 m). Besides, seven ranges and mountain massifs have peaks exceeding 4000 m (Munkh-Khirekhan, Tsast-Ula, Northern-Chuysky Alps, Kharkhira, Khangai, Sutai-Ula, Turgen-Ula), and other 10 ranges and mountain massifs of Altai and Sayan have peaks higher than 3700-3900 m. The whole system becomes lower from Altai to the north-east. Thus, highest peaks of ranges of Sayan are predominantly 1800-2300 m high, though absolute height of Munku-Sardyk mt. is 3491 m. At the border of West and East Sayan, a mountain knot with a summit of Grandioznyi Peak (2922 m) is situated. The lowest altitudes are typical for Kuznetsky Alatau (400-800 m, maximal altitude is 2178 m - Verkhni Zub [Upper Tooth] mt.), and Salair (400-600 m); both ranges are situated longitudinally. Intermountain depressions Minusinskaya, Kuznetskaya, Kanskaya and others lay at the altitudes of 150 to 300 m a.s.l. Absolute altitudes of these depressions grows southward; e. g., Chuya depression is situated at 1750-1900 m a.s.l. A remarkable peculiarity of Altai-Sayan mountain country is the multistage construction of the whole elevation with three basic levels of planation as well as a presence in the central cupola-shaped elevation of the extensive high-mountain plateau at the altitude of 2200-2400 m, and also the presence of a two-step system of the flat intermountain valleys at the altitude of 1400 and 1800-1900 m, and, finally, a combination of sublatitudinal and submeridianal (up to meridianal) direction of ranges. This peculiarity is connected to the fact that the bulks of ancient peneplene still present at the different altitudes and in different regions of the mountain country, which were exposed to multiple block elevation, and only at the end of the Tertiary and during the Quaternary periods they were renewed by recent tectonic activity and by ancient congelation which was stronger than the most recent one. This is why the summits of numerous ranges of the mountain country represent flat watersheds with separate peaks or both recently appeared and rather ancient massifs. This is especially characteristic to the Russian Altai, the southern part of Mongolian Altai, and Adzh-Bogdo range.|
Dominance of massive block elevations in the tectonic structure of Altai is also emphasized by the presence at the north-west periphery of Altai and also in Zaissan depression and, partly, in Barun-Khurai depression, of the front terrace at the altitude of neighboring plains - to an average of 300-340 m in the north and west of the whole country, and about 450-500 m in Zaissan and Barun-Khurai depressions. In the eastern part of Altai mountain mountry, the pedestal of the front foothills and, sometimes, of rather considerably and even sharply elevated high mountain massifs are higher, especially in the direction from the north to the south. This is quite evident, because it is formed by the levels of intermountain valleys - Minusinsk depression (lowest altitude 240 m), Tuva depression (640 m), Ubsunur depression (743 m), Depression of the Great Lakes (1028 m), Shargyn-Gobi (948 m), Transaltai Gobi (1000 m).
Altai-Sayan mountain country is also an important watershed. The major part of the upper (mountainous) basin of Ob and Irtysh, the minor part of the basin of Yenissey, and basins of rivers flowing into the closed depressions of Kazakhstan, Dzungaria and Mongolia, are situated here. The latter are the big depressions of the northern part of Dzungarian Gobi (Urungu-Noor lake, which just recently has been isolated from the basin of Irtysh), a part of the Depression of the Great Lakes, the borders of Barun-Khurai depression, and also the closed depressions of the lakes Achit-Nuur, Ereg-Nuur and Tsagan-Nuur in the north and Alag-Nuur in the south, as well as of the biggest lake of the region - Uvs-Nuur (Ubs-Nuur). The mountain country is covered with a dense web of rivers (somewhere rivers flow through the big ranges).
However, contemporary congelation of Altai is rather moderate although Altai is a comprehensive centre of glaciations of the whole country: about 1500 glaciers of a general square ca. 910 km2 are concentrated here. The main center of congelation in Altai is a mountain knot Tavan-Bogdo-Ula, where the biggest valley glaciers are situated (chiefly in Mongolia). Another big centers of glaciation are the glaciers of Belukha, Northern-Chuysky Alps, Southern-Chuysky Alps, Mest-Ula, to a less degree - glaciers of Turgen-Ula and Mongun-Taiga. The ice cupolas of Tsast-Ula, Sutai-Ula and Tsengel-Ula are apparently remnants of the past, much stronger, glaciation. Congelation of high mountain massive Munkh-Khirekhan is very peculiar: small glaciers in narrow valleys exist as a result of gradual degradation of pendent glaciers, not forming a continuous ice cover of the tops. Some other ranges also have small glaciers and firn fields. In general, however, glaciers form only an insufficient part of the drain of the biggest rivers flowing from Altai mts. The annual melting of the rather thick snow cover plays a greater role, especially in northern and western parts of Altai, as well as in the knots of interception of wet air masses (orientation of which is mostly south-western).
Vegetational cover (principal characteristics)
Because of the exceptional diversity of environmental conditions, vegetation cover of Altai mountain country is also highly diverse in its' different parts, and in some of them it is exceptionally peculiar. The principal features of distribution of vegetation are determined here, first of all, by latitudinal, zonal and sectoral position of the territory, and also by differences in the system of altitudinal zonality in different parts of the mountain country, which differ in their localization both in the system of zonality and within the mountain country. The northern part of Altai is situated in the subzone of northern forest-steppe, but through the forests of Kuznetsky Alatau (its western macroslope) it is connected also with the southern plain taiga of Tshulym-Ketsky taiga region. A comparatively small part of Western Altai is connected directly with southern plain forest-steppe of Ob-Irtysh watershed, whereas the main part of Western Altai has a connection with the steppe zone (under specific conditions of eastern part of Central Kazakhstan Highlands). Northern-Turan-Dzungarian desert types become a zonal element only at the far south of Altai (southern slopes of Tarbagatai, Chinese and Mongolian Altai).|
However, at the western border of Altai some important factors of the influence of this giant mountain system on adjacent plains are visible. First of all, it is evident from the decrease of subzonal limits of forest-steppe and zonal limits of steppe and northern deserts southward (in the area of influence of mountains and in complicated conditions of low upland). This phenomenon is even more expressed in the east of Altai mountain country, where, under conditions of the "rain shadow" on the highly elevated plains, the Gobi-type deserts (in the south), then desert steppes (northward) and, finally, dry steppes and complexes "semideserts, dry steppes and genuine steppes" (in an insular conditions) are developed. This considerable shift of zonal limits nortward is, of course, noteworthy, but not unique: at the same latitudes the same shift northward is observed in the Turgai Hollow and in the north-eastern vicinities of Central Kazakhstan Upland.
The fact that Altai mountain country is situated on the border of two sectors of Northern Asia - West Siberian-Middle Asian-Himalayan and extreme continental Central Siberian-Central Asian-Indochinese - is also of a great importance. In general, this border runs next to 900 orient. long., but in Altai it is more complicated: it starts in an almost latitudinal direction along the Sayan range and Tchulyshman plateau, then - south-westward amidst Kuraiskaya and Chuyskaya steppes to the Ukok plateau - then, passing Tavan-Bogdo-Ula, eastward, to the Tsengel-Ula and Munkh-Khirekhan, south-eastward to Alag-Khirekhan, then again south-westward between Baitag-Bogdo and Ikh-Khavtgijn-Nuruu, and then - southward and westward through the ranges of Eastern Tian-Shan to the 800 meridian. This broken line represents the western limit of most continental phenomena (in high mountain conditions) on the Asian continent. Latitudinal and zonal borders also define difference between two basic systems of altitudinal zonality in AMC - with and without well developed forest belt (or belts), although the difference between these systems are not reduced to only this characteristic. The general composition of flora, vegetation, and formations of vegetation also display marked differences of these.
Shmakov A. I.
Animal world (principal details)
Diversity of natural conditions, in particular, a position of Altai-Sayan region at the limit of zoogeographical provinces, diversity of vegetation cover, climate differences lead to a great diversity of an animal world which is resulted in an enormous (under conditions of Palaearctics) number of taxa. On one hand, this is due to a presence in the fauna of both east- and west-Palaeoarctic species at the western or eastern limits of their distribution, respectively. On the other hand, the level of endemism is rather high especially in Mongolian Altai where (first of all in the south-wet part) a highly special combination of Siberian, Dzungarian, and autochtonous faunistic elements is observed. Vertical zonality is one of the main factors leading to the variability and heterogeneity of the Altai-Sayan fauna. The richest biodiversity of animal taxa is observed in the ranges of Central Altai, Southern Tuva and of course in SE Altai where the column of the vertical zonality is the most complete. Species typical for taiga, steppe, semi-desert, tundras of different types, can not rarely be found within the distance of few kilometers, e. g., in the ranges Kuraisky or Tannu-Ola. This phenomenon leads to the para- or sometimes sympatry of the species from different faunistic groups.|
A history of Altai and Sayan was so that alpine belt of these mts. is currently inhabited by numerous arctic-alpine faunistic elements with disjunct distribution ranges. Such a complex is mot developed in Central Altai (Chuysky Alps, Ukok plateau), in East Tuva and Pre-Baikal region (Pribaikalye). Deserts. Semi-deserts, and steppes of southern part of the region are inhabited by a specific fauna combining Dzungarian and Central Asian elements. The beetles, especially Tenebrionidae, desert moths (Coleophoridae, Phycitidae, Cossidae, Noctuidae), spiders, reptiles, desert birds, bats and rodents are rather abundant.
Dry montane steppes are not faunistically rich but many highly specialized animals occur there. Spiders, beetles, reptiles (blizzards), various Passeriformes, rodents play a big role in montane-steppe faunistic complexes.
Forests, forest-steppes, and steppes of Altai and Sayan are most rich with animals. The fauna of these belts includes many species with rather wide distribution (Trans-Palaeoarctic, East- or West -Palaeoarctic). Because of specific conditions and isolating effect of mountain ranges, a good amount of such species is represented in Altai and Sayan by rather distinct subspecies or specific ecological forms. Tundras of different types are inhabited by specific fauna which includes, besides arctic-alpine elements, also rather high per cent of species endemic to the mountains of Siberia and South Mongolia.
It should be noted that the fauna of Altai-Sayan region is studied very irregularly. While the level of knowledge on the fauna of Rusian and Rudny Altai, Sayan and Pre-Baikal region is comparatively satisfactory, the vast areas in Mongolia and West China represent "white spots" in this respect. The data on the animal world of such isolated and interesting areas as the ranges Baitak-Bogdo and Adzh-Bogdo, Barun-Khurai depression, some ranges and reservoirs in the Chinese Altai are nearly absent. Therefore, it can be assumed that the real level of animal endemism in Altai and Sayan is (probably considerably) higher than it is currently estimated. This is especially true with regards to the fauna of spiders and insects; a study of these groups is most urgent at the present moment in view of resolving both taxonomical and zoogeographical problems. As it was emphasized by a well-known Russian zoologist and zoogeographist, O.L. Kryzhanovsky, a clarification of bigeographic limits is greatly based on the study of fauna of Invertebrata. This problem is especially actual for Altai-Sayan region situated within both Boreal and Ancient Mediterranean provinces.
Another problem is a study of rare and endangered species of animals in Altai and Sayan, including study of biology, distribution, and a monitoring of their population. The fauna of Altai- Sayan region includes a good number of rare and endangered species of mammals, birds, invertebrates, protected by Red Books of different level. However, estimation of a number and a condition of the populations of rare species is optimal within the natural limits of distribution ranges and not within the sites artificially outlined by administrative borders.
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