Chapter 4: Grasslands in Central Asia

In what kind of a climate are the grasslands growing in Central Asia, in NE China and on the Tibetan High Plateau? We shall find out more about this in Ecosystems of the World 8B Natural Grasslands, Eastern Hemisphere. Edited by Robert T. Coupland (1993) Grasslands of China. By Zhu Ting-Cheng, Institute of Grassland Science, Northeast Normal University, Changchung, Jilin, P. R. of China. Zonal grassland regions in northern China, Table 3.1 p. 64.

Meadow steppe

In NE China, 120 to 250 m above sea level. The ground is usually flat. Precipitation 350-500 mm av. 425 mm ppt yr. 1800-2500° temperature about 10°C (daily mean temperature above 10°C). Forage yield 1.5-2.5 t/ha = 150 to 250 gDM/m² yr, average 200 gDM/m² yr. 200 gDM/m² yr : 425 mm ppt yr = 0.4705882353 gDM/m²/mm ppt yr. near 43°N = ca. 40 kcal cm² yr net radiation at earth’s surface.

Typical steppe

In the north-eastern and central part of the Inner Mongolian plateau and extends southward into the loess plateau. Elevation ranges from 800 to 1400 m. Precipitation 280-400 mm av. 340 mm ppt yr. 1900-2400° temp. sum above 10°C. Forage yield 0.8-1.0 t/ha = 80 to 100 gDM/m² yr, av. 90 gDM/m² yr. 90 gDM/m² yr : 340 mm ppt yr = 0.2647058824 gDM/m²/mm ppt yr. near 43°N. Ca. 40 kcal cm² yr net radiation at earth’s surface.

Desert steppe

Desert steppe is the most arid type of grassland. Desert steppe occupies a belt across Inner Mongolia west of the typical steppe and extends into Ningxia Huizu Zizhiqu and the eastern part of Gansu province (the northern and north-western parts of the loess plateau). Precipitation 250-310 mm = av. 280 mm ppt yr. 2100-3200° temp. sum above 10°C. Forage yield 0.2 t/ha = 20 gDM/m² yr. Herbage yield, which is dependent on moisture supply, is highly variable from year to year, but is always less than 100 g m². 20 gDM/m² yr : 280 mm ppt yr = 0.07142857143 gDM.m²/mm ppt.yr. 41°N = 40 kcal cm² yr net radiation at earth’s surface

Shrub steppe

Shrub steppe is transitional between grassland and shrub forest. Islands of shrubs are growing there in a sea of herbs and grasses. Precipitation 380-460 mm av. 429 mm ppt yr. 2400-4000° temp. sum above 10°C. Forage yield 0.5 t/ha = 50 gDM/m² yr. 50 gDM/m² yr : 429 mm ppt yr = 0.1165501166 gDM.m²/mm ppt yr. 48°N = ca. 50 kcal cm² yr net radiation at earth’s surface

Alpine Steppe

This type covers extensive areas of the Tibetan plateau of south-western China. Annual precipitation ranges from 450 to 700 mm and annual air temperature accumulations (above 10°C) are from 200 to 500. Because of low temperatures and shallow soil (often with a permafrost layer), the grass canopy is no taller than 20 to 30 cm. Herbage yield is about 20 to 35 g m². Precipitation 450-700 mm av. 575 mm ppt yr. <500° 10°C temp. sum. Forage yield 0.20-0.35 t/ha = 20-35 gDM/m² yr, av. 27.5 gDM/m² yr. 27.5 gDM/m² yr : 575 mm ppt yr = 0.04782608696 gDM.m²/mm ppt yr.

Yield of dry matter in four types of meadows in northern China

After: Zhu Ting-Cheng (1993:72) Table 3.2

Dry Steppe on Tibetan High Plateau

Large parts of the Tibetan High Plateau are covered now with dry steppe. In what kind of a climate is this dry steppe growing up there? And how much fodder does it produce? Would an elephant find there enough to eat? This also shows us, where the Yak is still able to live. And it may also show us, on what kind of a plant-cover the Jarkov mammoth would have had to graze, if it had lived in central eastern Taimyr during the height of the Last Glaciation.

George B. Schaller is Director of Science for International Programs for the Wildlife Conservation Society. He reports about his findings in his new book Wildlife of the Tibetan Steppe (1998):

"The Chang Tang Reserve in Tibet, at about 34°N and 86°W. In the south the lakes generally lie at an elevation of 4300-5000 m, whereas in the north they lie at around 4800-500 m. Permafrost may occur at elevations above 4100 m in areas with an average annual temperature of –2.5 to –3.5°C. Much of the northern Chang Tang lies within this permafrost zone. The maximum depth of the seasonal thawed sediment layer was 1-6 m in the eastern Chang Tang along the Lhasa-Goldmud highway., and permafrost thickness reached 155 m. In mid-June 1992 we dug three holes at 5000 m in the plains near Toze Kangri north of the Ari Basin. Permafrost was reached at 59-63 cm, indicating only a shallow thawed layer beyond which the plant roots had not penetrated." Schaller, G. B. (1998:30, 31)

"Lying generally between 4000 and 5000 m, the alpine steppe is cold and windy, the sun’s radiation is intense, and the daily changes in temperature are great. Plant coverage is sparse, seldom more than 30%, and the soil is poor (gravel, sand, silt, and clay, alluvial or eolian in origin) and without a sod layer. The alpine steppe extends up the hillsides to 5200-5300 m, at an elevation above which only scattered subnival species persist... Alpine steppe is covered predominantly with Stipa grass, an important feed for most ungulates, especially in winter." (1998:36, 37)

"Since most terrain lies above 4600 m and the vegetation limit lies at around 5200 m, available habitat is confined to a narrow band of plains and hills. Plant growth is dependent on precipitation and temperature. With winter long and precipitation scant, the growing season is short, from late May or June to September." (1998:212)

"Biomass. Much of the ground bare and most vegetation less than 15 cm tall, the Chang Tang provides little aboveground standing biomass. In the southern Chang Tang, outside the reserve, Cincotta et al. (1991) found that only 28% of their study area supported a net primary productivity greater than 10 g/m². The total biomass of the Aru Basin is about 15.6 g/m². The standing crop of most areas probably lies between 8 and 16 g/m², or 80-160 kg/ha, dry weight" Schaller, G. B. (1998:220, 221)

Water needed

This also shows us, how the mammoth would have fared on the dry arctic steppe, if it had tried to live up there during the height of the Last Glaciation. Would the mammoth find enough drinking water on the dry steppe of the Tibetan High Plateau?

G. B. Schaller: "Drinking water may be critical to ungulates in arid environments in that it can restrict their movements to the vicinity of streams, springs, and other such sources. Fresh water is seasonally scarce in the Chang Tang. Most lakes and streams are brackish or saline. Traveling cross-country in desert-steppe, we sometimes found no drinking water for 100 km or more. Occasionally a puddle with seepage water occurred in a dry streambed, and kiangs and yaks visited such sites to drink. Blue sheep sometimes descended to a rivulet, and chirus may drink at a stream, though they usually waded across without halting." (1998:242)

"The total aboveground plant biomass of the Aru Basin in the Chang Tang Reserve is about 15.6 gDM/m² per year. Most areas in the Chang Tang Reserve in the Tibetan Plateau, with its Alpine steppe has an average aboveground plant mass of 8 to 16 g/m² or an average of 12 gDM/m² per year. In the south of the Chang Tang Reserve, average annual precipitation is about 300 mm. And in its northwestern part, only about 60 mm per year, according to the map in G. B. Schaller (1998:25) Fig. 2.2. The average annual precipitation in the middle of the Chang Tang Reserve is about 180 mm.

15.6 gDM/m² yr in the Aru Basin : 180 mm ppt yr = 0.0866666 gDM.cm²/mm ppt yr. On most of the areas of the Chang Tang Reserve on the Tibetan Plateau annual average aboveground plant production is about 12 gDM/m² yr. 12 : 180 = 0.0666666 gDM.m²/mm ppt yr.