Location and General Description
The Tian Shan extend 2,500 km east-to-west across Central Asia. An extensive mountain system that comprises part of the basin-and-range topography of northwestern China, the mountains were formed by faulting and uplift during the Pliocene, 7 million to 2.5 million years ago. Like the Rocky Mountains of North America, the Tian Shan are thought to be one of the greatest examples of intra-continental mountain-building in the world. Ridges average about 4,000 m while the highest summits exceed 7,400 m elevation.
The western part of the Tian Shan breaks down into a complex series of ridges and lake basins that extend westward toward the steppes of Central Asia, away from the steep and dry, basin-and-range topography of northwestern China. Here mountains and foothills are exposed to moist arctic air from western Siberia. Increased precipitation in this part of the Tian Shan promotes vegetation at low elevations that is more mesic than in the eastern part of the range where mountains rise from the deserts of the Tarim and Junggar Basins. Due to increased precipitation and diverse habitats, the western foothills of the Tian Shan are richer in plant species than other parts of the range.
Zonation patterns are well-defined in the northwest part of the Tian Shan. River basins at the foot of the range support a shrub and meadow savanna with poplars and large sand dunes. Grasses along the Ili River in eastern Kazakhstan include feather-grass Stipa and fescue Festuca. Dominant shrubs are Artemisia spp., similar to the sagebrush of the North American Great Basin. Lower foothills (150 to 660 m) support semi-desert vegetation dominated by salt-tolerant shrubs like Tamarix spp. and Alhagi camelorum together with Artemisia steppe. The major rivers, including the Syr Darya, Ili (Yili), and Chu, flow generally westward.
The climate of this region is influenced by its distance from the sea and the sharp change of elevation from neighboring plains. Conditions vary from permanent snow in high-altitude cold deserts to hot deserts in the lowlands. From the end of June through mid-August most afternoons reach 32°C (90°F) or higher, with an average annual maximum of 40°C (104°F). During the winter months, temperatures remain below freezing for about 40 days. The coldest month is January when winds blow in from Siberia.
Deciduous forests grow at elevations ranging from 1,200 to 1,700 m. One notable tree that grows along river valleys at these elevations in the Yili region of the Tian Shan is Sievers’ apple (Malus sieversii). These trees are restricted to moist places sheltered from cold, dry winter winds but exposed to moist air from the west. The presence in the Tian Shan of wild apple and other temperate trees species like Ansu apricot (Prunus armeniaca) and the maple (Acer semenovii), is significant. These trees represent the remnants of broad-leaved temperate forests that flourished in this area during the Tertiary, but were nearly extirpated during the Pleistocene glaciations of the past two million years. Thorny shrubs like Rosa spp.and Berberis spp. are also abundant here, especially in places that are heavily grazed.
Understory vegetation in the deciduous forests of this ecoregion is different from other parts of the Tian Shan. Grass diversity is higher than in the desert foothills to the east and includes the endemic grass, Atraphaxis muschketovii, various species of tulip (Tulipa spp.), some of which are endemic, desert candle (Eremurus spp.), and the composite Ligularia macrophylla.
In the higher part of the deciduous forest belt, stands are dominated by aspen (Populus tremula) and the "nettle-tree" (Celtis caucasia). There is an understory of economically important wild plants such as the aromatic (Dictamnus turkestanicus). River valleys support birch (Betula tianshanica) and sea buckthorn (Hippophae rhamnoides).
A number of endemic species occur in this ecoregion. One example is Niedzwedzkia semiretschenskia, a perennial semiherbaceous plant with beautiful flowers and the oldest relic endemic in Kazakhstan. This species has survived only in the Chu-Ili mountains at an area of 7 hectares. The sagebrush Artemisia cina is a steppe endemic species of southern Kazakhstan and occurs on salty grey-brown soils. This plant is widely used in medicine for treating ascariasis and as a bactericidal agent; it is also used in perfume industry. Other endemic plant species include Tulipa greigii and Juno orchioides.
Common mammals include red fox (Vulpes vulpes), corsac fox (Vulpes corsac), wolf (Canis lupus), steppe cat (Felis libyca), jungle cat (Felis chaus), weasel (Mustela nivalis), Altai ferret (M. altaica), ferret (M. eversmanni), marbled polecat (Vormela peregusna), badger (Meles meles), saiga antelope (Saiga tatarica), arkhar (Ovis ammon), tolai hare (Lepus tolai), Indian porcupine (Hystrix leucura), various jerboas (Allactaga jaculus, A. elater, A. bobrinskii, Alactagulus saltator, Pygerethmus zhitkovi, Dipus sagitta, Scirtopoda telum), birch mouse (Sicista subtilis), sousliks (Citellus fulvus, C. erythrogenys), gerbils (Rhombomys opimus, Meriones erythrourus, M. meridionalis, M. tamariscinus), water vole (Arvicola terrestris), vole (Microtus arvalis), long-eared hedgehogs (Hemiechinus auritus), shrews (Sorex minutus, Crocidura suaveolens, C. leucodon), mice (Mus musculus, Apodemus agrarius). Birds found in this ecoregion include larks (Galerida spp.), doves (Streptopelia spp.), wheateaters (Oenanthe spp.), Egyptian vulture (Gyps fulvus), saker falcon (Falco cherrug), hawks (Accipiter nisus, A. badius), long-legged buzzard (Buteo rufinus), kite (Milvus korshun), falcons (Falco tinnunculus), buntings (Emberiza spp.), warblers (Sylvia spp.), and shrikes (Lanius spp.). Common reptile species in the ecoregion are lizards (Lacerta spp.), runners (Eremias spp.), skinks (Ablepharus spp.), geckos (Cyrtopodion spp.), rat snakes (Coluber spp.).
The most spectacular large predator, Turanian tiger (Panthera tigris virgata) lived in this ecoregion in the 19th century (along the Ili river tugai, or desert riparian forest) but was hunted to extinction about 100 years ago.
Among rare and endemic animal species found in the ecoregion included in IUCN or local (Kazakhstan) Red Data Lists are goitered gazelle (Gazella subgutturosa), corsac fox, arkhar, saiga antelope, black vulture (Aegypius monachus), imperial eagle (Aquila heliaca), short-toed eagle (Circaetus gallicus), lesser kestrel (Falco naumanni). The Central Asian tortoise (Testudo horsfieldii) is also included in the IUCN Red Data list. The Kulan, or onager (Equus hemionus onager), is an endangered subspecies of Asian wild ass which has been recently introduced in this ecoregion (Kapchagai preserve) from Turkmenistan, where the only remaining wild population lives in the Badghyz Reserve.
On the western side of the border, in Kyrgyzstan and Kazakhstan the population is denser and industrialization more advanced. Oil, coal, iron, and copper deposits are exploited and contamination from such extraction affects air and water quality. Habitat in the foothill steppe areas has been negatively impacted by grazing and hunting.
Types and Severity of Threats
Overgrazing, oil and mineral extraction, and poaching are the major threats to this ecoregion. Livestock raising is also a dominant activity. Wild ungulates are the most affected large animals by human influence in this ecoregion, both from traditional hunting by the local population, but also trophies prized by foreign hunters. A number of rare plant species are of a high value as food or medicinal plants.
Justification of Ecoregion Delineation
This ecoregion skirts the northwestern mountains between the desert and Tian Shan conifer forests at approximately 150-660 meters. It includes the semi-deserts and steppes of inner and north Tian Shan regions according to Pereladova’s (1998) map of Central Asian ecosystems. In China, the boundary is based on CVMCC (1979) Vegetation Map of China classes shrub desert (60b) and agriculture (70b) that extend across the border with Kazakhstan.
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Prepared by: Chris Carptenter, Galina Fet, Victor Fet
Reviewed by: In process