Location and General Description
The Alashan Plateau is a region of low mountains separated by intermontane basins. Ridges attain elevations of 2,000 to 2,500 m while the basins tend to lie at 1,000 to 1,500 m. The whole ecoregion is enclosed by the Helan Mountains to the East and the Qilian Mountains and the northeastern part of the Tibetan Plateau to the southwest. Northward, the plateau extends into southern Mongolia where it constitutes a large portion of the cold, dry Gobi Desert. It is bounded on the north by the Altai Mountains that separate the desert from grassland and forest ecosystems that are transitional to the Siberian taiga. Because the region is enclosed by mountains and lies a great distance from the sea, conditions here are arid. However, numerous oases, fed by mountain snowmelt, occur along the southern flank of the Qilian Range.
The driest parts of the Alashan Plateau consist of shifting sand in the south and denuded, stony landscapes in the north. For example, more than 80 percent of the Badain Jaran Desert in the western part of the Alashan Plateau, an area of 33,000 km2, consists of shifting sand blown into dunes 200 to 300 m high. Arid locations that are more stable acquire communities of the salt-tolerant, xerophytic shrub species, saxaul (Haloxylon ammodendron) and Reaumuria soongolica. Once sand dunes become stabilized with sufficient cover of shrubs like these, they cease to shift and soil development can occur, albeit slowly, enabling a more diverse assemblage of plant species to colonize the site. Other places that are slightly less arid support semi-desert shrub communities, comprised of wormwoods (Artemisia salsoloides, A. ordosica), beancaper (Zygophyllum xanthoxylum), and Calligonum mongolicum.
A few rivers, such as the Dong He and Xi He, traverse the Alashan Plateau, and the Elbow Plains of the Huang He (Yellow River) lie near its eastern edge. Typical vegetation here consists of riparian forests dominated by poplar (Populus diversifolia) where the water is fresh and Tamarix spp. where the water is brackish. Low-lying depressions in the western part support meadows and flooded reed beds of Phragmites communis.
The southern margin of the plateau lies at the foot of the Qilian Mountains. Streams that flow from the mountains seep underground when they reach the unconsolidated alluvial soils at the foot of the mountains, then emerge again near the valley floor in a "green necklace" of desert oases.
The climate of the Alashan Plateau is severe with large seasonal and diurnal temperature variations. Annual precipitation ranges rarely exceeds 150 mm per year, and it is both spatially and temporally variable. In the drier areas of the Gobi Desert in southern Mongolia, several years may pass with no measurable precipitation, or enough rain may fall in one summer to create a green flush of vegetation and fill hundreds of ephemeral ponds with fresh water.
The Great Gobi Protected Area, located in southern Mongolia, conserves much of the northern part of the Alashan Plateau. Over 410 species of plants, 49 mammals, 15 reptiles and amphibians and more than 150 bird species have been recorded in this protected area.
A single mammal, Przewalski's gerbil (Brachiones przewalskii) is considered endemic to this ecoregion.
According to the Mongolia Ministry for Nature and the Environment, "the larger Southern Altai Gobi exhibits flora and fauna typical of the deserts of Central Asia. Desert steppe species are found primarily at higher elevations, and saxaul forests occur on mountain slopes. Moving south, the climate becomes increasingly arid, and lower in elevation. Southern regions of the Southern Altai Gobi are characterized by a special zone of stone-covered super-arid desert where higher plants are largely absent except in dry washes and depressions." This reserve supports one of the two remaining populations of wild Bactrian camels (Camelus ferus). Its estimate population size is about 300 individuals. The other population is found in the Taklimakan Desert. Asiatic wild ass (E. hemionus) are common in the reserve. About 30 Gobi brown bears, a subspecies of (Ursus arctos), survive in the mountains here. Goitered gazelles (Gazella subgutturosa) also occur here. Reptiles found in this ecoregion that are endemic to Central Asia include the Gobi gecko (Cyrtapodion elongatus) and Tatar sand boa (Eryx tataricus).
Mountainous areas in the northern part of this ecoregion support populations of three of Central Asia’s large predators: snow leopards (Panthera uncia), brown bears (Ursus arctos), and wolves (Canis lupus). The ibex (Capra sibirica) and the Gobi argali (Ovis ammon) also occur here.
In China, Anxi Bebi Caoyuan Nature Reserve (3,400 km2) is located in the southwestern part of the Alashan Plateau. Here, grasslands are sustained by springs that flow from the foot of the western Qilian Mountains. Although wild ungulates have been extirpated from this area, potential exists to reintroduce the Saiga antelope (Saiga tartarica) and perhaps other species as well. There is also an opportunity to increase the amount of desert grassland under protection. This would be a valuable contribution to conservation of biodiversity in this ecoregion, because desert grasslands have the potential to support rich wildlife communities.
In general, wildlife populations of the Alashan Plateau are larger and less vulnerable in Mongolia than in China. Typical wildlife of the stony deserts include goitered gazelles, (Gazella subgutturosa) which are probably now extinct in China, and Przewalski’s gazelles (Procapra przewalskii), whose population is thought to be declining in China. Bactrian camels (Camelus ferus) used to roam widely through this ecoregion, but are now extirpated within China except for one population in the southeastern part of the Taklimakan Desert.
The Great Gobi Protected Area (53,000 km2), located in southern Mongolia, conserves much of the northern part of the Alashan Plateau. This expansive reserve includes two units, the Southern Altai Gobi (44,000 km2) and the Dzungarian Gobi (8,810 km2), the first of which is located in the Alashan Plateau ecoregion.
In the Chinese part of the Alashan Plateau, human population is increasing due to government-initiated translocation programs that are underway. These programs are accompanied by efforts to convert "empty desert" to irrigated agricultural land. In most well-watered sites, irrigated agriculture is very productive so that little trace of the native forest and woodland vegetation remains. With population increases come increases in hunting and trapping of wildlife. Today, populations of gazelles are thought to be in decline. Illegal capture of falcons for export to the Middle East is also practiced here.
Types and Severity of Threats
Recent efforts to fence grassland areas to control livestock is disruptive to wild ungulate populations. Other problems for wildlife that accrue from animal husbandry are desertification and replacement of local plants with unpalatable (spiny or toxic) species as well as the practice of pumping groundwater from bore holes. This practice concentrates livestock and leads to overgrazing.
In Mongolia, threats to protected areas include uncontrolled motor-vehicle use and high concentration of humans and domestic livestock at scarce natural water sources that are critical to the survival of wildlife populations.
Justification of Ecoregion Delineation
This ecoregion has a wide east-west expanse from the Ordos desert in the east to the Peishan desert, southernmost of western Gobi, in the west. In China, the boundary is based on the CVMCC (1979) Vegetation Map of China classes corresponding to shrub desert (51b,d, 52, 55, 56, 59). This is comparable to the Alashan Plateau biogeographic subunit in the Takla-Makan-Gobi Desert according to Mackinnon et al. (1996). In Mongolia, the ecoregion is defined as desert in Mongolia Ministry for Nature and Environment (1996). This corresponds to the Transaltai-Gobi and Alashan Gobi in Barthel (1983) and Haase (1983).
Barthel, H. 1983. Die regionale und jahreszeitliche Differenzierung des Klamas in der Mongolischen Volksrepublik. Gartenbau 25: 85-86, Berlin.
Chinese Vegetation Map Compilation Committee (CVMCC). 1979. Vegetation map of China. Map (1:10,000,000). Science Press, Beijing, China.
Conservation International. Retrieved (2000) from: http://www.conservation.org/science/cptc/capbuild/unesco/asia/grtgobi/species.htm
Haase, G. 1983. Beitrage Zur Bodengeographie der Mongolischen Volksrepublik. Studia geogr. 34: 231-367, Brno.
Laidler L. and K. Laidler. 1996. China’s threatened wildlife. Blandford, London.
MacDonald, D., editor. 1999. The encyclopedia of mammals. Barnes and Noble Books.
MacKinnon, J. 1996. Wild China. The MIT Press, Cambridge MA.
MacKinnon, J., Meng Sha, C. Cheung, G. Carey, Zhu Xiang, and D. Melville. 1996. A biodiversity review of china. Worldwide Fund for Nature (WWF) International, Hong Kong.
Mongolia Ministry for Nature and Environment, United Nations Development Programme (UNDP)/Global Environment Facility (GEF), and World Wide Fund for Nature (WWF). 1996. Mongolia’s wild heritage. Avery Press, Boulder, Colorado.
Xianying Xu, Renduo Zhang, Xuzhang Xue, and Ming Zhao. 2000. Determination of Evapotranspiration in the Desert Area Using Lysimeters. Communications in Soil Science and Plant Analysis 29(1): 1-13. Retrieved (2000) from:http://www.dekker.com/e/p.pl/00103624/029/001002/001/abs
Zhao Ji, editor. Zheng Guangmei, Wang Huadong, Xu Jialin. 1990. The Natural History of China. McGraw Hill Publishing Company, New York.
Prepared by: Chris Carpenter
Reviewed by: In process