grasslands, which include deserts, oases, and lowland meadows in the basins; diversified vertical vegetation belts of steppes, meadows, and forests in the mountains; and high-cold desert and steppe on the plateau.
The vertical climatic change in the Altai and Tianshan mountains (Map 1-5) is very prominent. The mean annual temperature in these mountains is between 0° and –5°C, the warmest monthly temperature is less than 15°C, and the coldest monthly temperature is generally below –20°C. The growing season in the Bayinbuluke grasslands lasts for 167 days and the green period for 107 days. Thermal conditions are better in the Ili valley: the mean annual temperature of Korgas reaches 9.6°C, the warmest monthly temperature is 23.5°C, and the coldest monthly temperature is –9.7°C. The growing season for grass in this area is 257 days, and the green period is 221 days. The mean annual temperature in the pediment of the Altai Mountains and the Ertis River valley is 4°C, the growing season for grass is 211 days, and the green period is 178 days. Below a certain altitude—1500–2000 m in most of these mountains, 1100–1600 m in Ili—the winter temperature inversion produces a warm belt that creates fine winter pastures. Mean annual precipitation is generally less than 250 mm in the low-montane desert belt, 250–500 mm in the midmontane steppe belt, and more than 500 mm in the montane forest meadow belt.
The mean annual temperature in the Junggar Basin of northern Xinjiang is 6–7°C. The warmest monthly temperatures in this basin exceed 20°C, and the coldest monthly temperatures are between –12 and –20°C. The annual precipitation is 100–200 mm. With long, cold winters, dry, hot summers, and strong damaging winds, the Junggar supports little good pasture, and conditions are difficult for livestock.
Thermal conditions are better in the Tarim Basin of southern Xinjiang. The mean annual temperature in this basin is 8–14°C; the warmest monthly temperature in most areas is 25°C, although it can reach 32.7°C in the Turpan Depression. The coldest monthly temperature is between –6 and –10°C. The growing season for grass is more than 250 days, and the green period more than 220 days. Precipitation is generally less than 50 mm, and less than 10 mm in Turpan. With so little rainfall the Tarim is dominated by desert grassland, which is of low quality and has low animal carrying capacity (see Table 7-1).
Xinjiang's natural grasslands can be classified by dominant vegetation into four general types and respective subtypes, as follows (XIST/IOB, 1978).
Meadow, the best-quality grassland, accounts for 18.3% of Xinjiang's grasslands and can be divided into three subtypes, according to the topography in which it is found. Mid- and low-montane tall-grass meadow consists of various