Location and General Description
The Qaidam is a graben, or sunken valley, that lies between the Altun Mountains to the north (highest peaks exceed 6,000 m) and the Kunlun Mountains to the south (highest peaks exceed 7,000 m). The western part of the Qilian Mountain Range also encloses the Qaidam Basin. It is about 850 km east-to-west and about 300 km north-to-south with an elevation of 2,700 to 3000 m.
Because of high elevation and great distance from the moderating effects of the ocean, the Qaidam Basin has a severe climate despite its position at lower temperate latitudes. Winters are long and very cold, and the region is subject to high winds and sandstorms during spring. Mean annual temperature is about -6oC, although temperatures during the warm season average 18 to 20oC on the floor of the basin. The Qaidam lies north of numerous other mountain ranges that it is almost completely cut off from the South Asian monsoon that brings large amounts of precipitation to much of the Tibetan Plateau. Mountains to the north block incursions of arctic moisture. As a result, the center of the basin, especially the western part, is one of the driest places in China (mean precipitation is 35 mm per year) while higher elevations near the base of the mountains receive somewhat more precipitation, mostly during summer thunderstorms.
Most of the Qaidam Basin supports sparse desert vegetation on gravelly, well-drained soils. A typical pattern is scattered shrubs on the upper parts of alluvial fans where ground water lies closer to the surface, and in canyons where rivers emerge from the mountains. Flat areas farther from the mountains may almost completely lack vegetation. The eastern part of the basin receives more precipitation and has a relatively higher level of vegetation coverage. Dominant species include the cold-tolerant, xerophytic shrub, Haloxylon ammodendron (Goosefoot Family Chenopodiaceae), the tamarisk (Reaumuria spp.), and the gymnosperm Ephedra przewalski. Other species include Nitraria vannoides, Salsola collina, and Tamarix spp. The western part of the basin consists of arid desert with almost no vegetation at all, including expanses of gravel, and shifting sand. Other areas of the basin are covered in salt deposits as much as 15 m deep.
The southern part of the Qaidam Basin, where elevations are lowest, acts as a sink for rivers flowing from the adjacent mountain ranges. Extensive saline meadows and salt marshes occur in this part of the basin. Characteristic vegetation in this frigid, flooded, saline/alkaline environment consists of Koresia littledalei, Aneurolepidium dasistachyum, and Polygonum sibiricum.
Surrounding mountain slopes at higher elevations support shrubs adapted to cold, windy, semi-arid conditions. This alpine desert vegetation consists mainly of Ajania tibetica and the cushion plant Ceratoides compacta. Small needle-grasses like Stipa subsessiliflora form a thin ground cover in such places.
Oases, watered by snowmelt from the surrounding mountains, support forests of the poplar Populus diversifolia. The ecology of these places has been severely altered by irrigated agriculture.
Large mammals recorded during a 1986 survey of the Qaidam Basin and adjoining mountain valleys (Cai et al., 1989) include the predators brown bear (Ursus arctos), wolf (Canis lupus), red fox (Vulpus vulpus), lynx (Felis lynx) and the ungulates goitered gazelle (Gazella subgutturosa), blue sheep (Pseudois nayau). Wooly hare (Lepus oiostolus) was also found. Mammals recorded in 1972 that were not detected in 1986 include Asiatic wild ass (Equus kiang) and wild yak (Bos grunniens). Hides of a number of other mammal species were also recorded in 1986, although these might not have come from Qaidam Basin populations.
Qaidam Basin is one of the few places in China where Bactrian camels (Camelus bactrianus) and Przewalski’s horse (Equus przewalskii) have been reported in recent years, although it is unlikely that either of these severely endangered mammals remains in the Qaidam Basin today. The basin does support a large number of domestic Bactrian camels. Scrubby and forested mountain valleys on the slopes to the south of the Qaidam Basin contain some of the richest wildlife habitat and wildlife populations, including musk deer (Moschus spp.) and Tibetan antelope (Pantholops hodgsoni).
Although reptiles in the region are not well-studied, at least one endemic lizard, the toad-headed agamid (Phrynocephalus vlangalii), occurs here.
Between 1946 and 1986, the human population of the Qaidam Basin increased 27-fold to 270,000. This increase was accompanied by a severe reduction in forest cover and an expansion of agriculture into marginal areas. Affected forests include Populus diversifolia in valley oases and conifer forest stands in outlying mountain valleys. Livestock grazing and hunting have also increased. The result of these trends has been a decline in wildlife throughout the region.
The Qaidam Basin currently lacks nature reserves or other types of protected areas, although salt marshes at the center of the basin could offer significant habitat for birds such as black-necked crane (Grus nigricollis) and bar-headed goose (Anser indicus).
Types and Severity of Threats
Mining of salt and potash are some of the extractive industries that occur here. Oil exploration and development of oil fields is another potentially disruptive activity that takes place.
The Qaidam Basin is the site of the Dulan agricultural resettlement plan in which large numbers of farmers from other parts of China are slated for settlement in areas inhabited by ethnic Tibetan herders. This project, initially endorsed by the World Bank but later discontinued amid international controversy, is still supported by the Chinese Central Government. Resettlement of 61,000 people to this area will accompany planting of windbreak forests and increased irrigation.
Justification of Ecoregion Delineation
The ecoregion boundary is based on CVMCC (1979) Vegetation Map of China classes shrubby desert (51d, 52, 56), sparse alpine vegetation (65), but also includes some saline shrub and meadow (31, 67) in the alluvial areas and sand dunes. This is comparable to the Qaidam Basin biogeographic subunit in the Takla-Makan-Gobi Desert according to Mackinnon et al. (1996).
Cai, Guiquan, Liu Yongsheng and B.W. O’Gara. 1990. Observations of large mammals in the Qaidam Basin and its periperhal mountainous areas in the People’s Republic of China. Canadian Journal of Zoology 68: 2021-2024.
Chinese Vegetation Map Compilation Committee (CVMCC). 1979. Vegetation map of China. Map (1:10,000,000). Science Press, Beijing, China.
Laidler L. and L. Keith. 1996. China’s threatened wildlife. Blandford, London.
Lu, J. 1995. Ecological significance and classification of Chinese wetlands. Vegetatio 118: 49-56.
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.
Zhao, Ji. editor. Zheng Guangmei, Wang Huadong, Xu Jialin. 1990. The Natural History of China. McGraw Hill Publishing Company, New York.
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Prepared by: Chris Carpenter
Reviewed by: In process