Location and General Description
This large ecoregion includes more than a million square kilometers of temperate grasslands on the inland side of Manchuria’s coastal mountain ranges and river basins. To the west are the desert regions of southern Mongolia and north-central China. Spreading to the southwest of the Da Hinggan Mountains, the Mongolian-Manchurian grassland ecoregion extends one arm west toward the Upper Selinga River Basin that drains ultimately into Lake Baikal in the Russian Far East and then to the Arctic Ocean. Another arm extends southwest toward the deserts of north-central China. Much of the ecoregion consists of nearly flat or rolling grasslands. The southwestern uplands of the Da Hinggan Mountains are also included. Their western slopes are gently inclined toward Mongolia while the eastern slopes drop steeply to the Northeast China Plain. Average elevation throughout the ecoregion is 1,000 to 1,300 m.
The climate is temperate. January mean temperatures are –9oC or less, decreasing westward. Annual precipitation, concentrated during a weak summer monsoon, decreases from an average of 400 to 450 mm in the east to 150 to 200 mm in the west. The trans-montane grasslands northwest of the Da Hinggan Mountains have especially cold winters because there are no mountains to offer shelter from prevailing northwesterly winds. Because of the "continental monsoon effect" created by winter season low pressure over the South China Sea, cold air is sucked southeast from the high latitude regions of Central Asia, creating much colder winter temperatures than occur at other regions of similar latitude. Mean January temperatures in this part of the ecoregion may be less than –20oC despite a comparatively low latitude (equivalent to Nova Scotia, Canada).
The Da Hinggan Mountains support dense forest cover in some areas. Lower slopes have deciduous broadleaf forests dominated by Mongolian oak (Quercus mongolica), or a mixture of species that include poplar (Populus davidiana, P. suaveolens), birch (Betula platyphylla), and willow (Salix rorida). Shrubs include members of the heath family (Rhododendron macromulata, R. dahurica, and Vaccinium vitis-idaea) and wild rosemary (Ledum palustre). Higher on the mountainside, spruce (Picea obovata, P. microsperma), larch (Larix dahurica), and Scotch pine (Pinus sylvestris), the most widely distributed of the world’s pine species, co-occur in shady sites at 1,300 to 1,700 m. Stony slopes support Japanese stone pine (Pinus pumila). Picea asperata occurs in sandy areas at 1,300 to 1,500 m in the Baiyin Aobao Nature Reserve (67 km2). Sunny slopes at the same elevation support montane grassland communities.
Dominant taxa here include feathergrass (Stipa baicalensis, S. capillata,and S. grandis), Festuca ovina, Aneurolepidium chinense, Filifolium sibiricuman, and Cleistogenes sqarrosa. Areas closer to the Gobi Desert regions support desert steppe that have lower productivity. Dominant species here include drought-resistant grasses (Stipa gobica, S. breviflora,and S. glareosa), forbs (Reaumuria soongolica, Hippolytia trifida, and Ajania fruticosa), and small, spiny shrubs that are well-adapted to arid conditions (Caragana microphylla, Ephedra equisetina, and E sinica). Other plant communities include: Kalidium gracile in areas of saline soils and salt marshes dominated by Scirpus rufus, S. planifolium, Ranunculus cymbalaria, and Phragmites communis.
Several species of severely threatened mammals probably occur on the Manchurian-Mongolian grasslands, although remaining populations are severely fragmented. Asiatic wild ass (Equus hemionus) may still occur in the Mongolia border regions, and populations of snow leopards (Panthera uncia) may possibly occur in small numbers in the mountain areas, although there are no records of its occurrence within this ecoregion.
Bactrian camel (Camelus ferus), Przewalski’s gazelle (Procapra przewalskii), and Przewalski’s horse (Equus przewalskii) have been extirpated from this ecoregion as a result of hunting and perhaps displacement by domestic ungulates.
The brown eared-pheasant (Crossoptilon mantchuricum) is the sole endemic bird. It is confined to scattered localities in the Luliang Shan, and mountains of northwestern Hebei, western Beijing, and central Shaanxi. It breeds in montane conifer forests, but winters in lower shrub-grasslands at the forest edge. Four nature reserves are crucial to its protection: Luyashan, Pangquangou, Wulushan, and Xiaowutai (Fuller and Garson 2000). Another reserve, Dalaihu (Hulun Nor) Nature Reserve (4,000 km2), includes a brackish lake which is the fourth largest in China. Marshes and Phragmites reed beds provide breeding habitat for the great-crested grebe (Podiceps cristatus), Oriental white stork (Ciconia boyciana), Japanese crane (Grus japonensis), and relict gull (Larus relictus). Two rare birds that breed on the adjoining plains are the great bustard (Otis tarda) and Oriental plover (Charadrius veredus).
In Mongolia, economic trends of livestock privatization and the collapse of the urban economy have caused people to return to rural lifestyles, contrary to the global trend toward urbanization. As a result, the number of herdsmen in Mongolia is reported to have tripled in the past decade to more than 450,000 while the number of livestock has increased by 30 percent
The results of studies raise concern about the possible effects of global change on the Manchurian-Mongolian grasslands. Studies by Xiao et al. (1995, 1996) indicate that the seasonal distribution and inter-annual variation in temperature and precipitation, especially during the late summer, are important controls on temporal dynamics of plant biomass, rain-use efficiency, as well as carbon flux and storage of these meadow steppe ecosystems.
Types and Severity of Threats
Sheep-grazing is a dominant activity, although goats are more abundant in the rockier, mountainous areas. In recent years, the number of goats raised on the grasslands has increased considerably due to the high prices for cashmere wool, which comes from goats. Because goats eat a wider range of plant species than sheep, and because they forage more aggressively and tend to consume the whole plant, this trend has contributed to degradation of the grasslands over a widespread area.
Wetland habitats (many brackish or saline) exist throughout these grasslands, and many offer important bird-breeding habitat. Threats to these areas include reed-cutting, excessive hunting, egg collection, and over-fishing.
Justification of Ecoregion Delineation
The eastern steppe regions from Hilbig (1995) and the Mongolia Ministry for Nature and Environment (1996) define the Mongolian portion of the ecoregion. The boundary in China is based on the CVMCC (1979) Vegetation Map of China grasslands (classes 37, 38, 39, 40, 41,43, and 44) with patches of deciduous forests and shrubs (15, 28) at higher elevations. This is comparable to all except the southwestern section (removed to form part of the Eastern Gobi desert steppe) of the Mongolian Steppe biogeographic subunit in the Mongolian-Manchurian Steppe Region according to Mackinnon et al. (1996).
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Prepared by: Chris Carpenter
Reviewed by: Batbold D. Otgoid