Semidesert Zones

natural zones in which semidesert landscapes predominate. These zones lie between the desert zone and the zone of steppes and savannas in the temperate, subtropical, and tropical belts of the northern and southern hemispheres. They have an arid climate, with winter temperatures generally ranging from 0° to 10°C and summer temperatures of 20°–25°C. The radiation balance is usually positive throughout the year (only in certain semidesert regions of the temperate belts is it sometimes negative during the winter), and it fluctuates between 1.68 and 8.4 megajoules per sq m, or between 40 and 200 kilocalories per sq cm. The evaporation is normally from three to six times the annual precipitation, which usually does not exceed 300 mm. There is little surface runoff, and rivers often dry up.

The soils of the semidesert zones are chiefly light chestnut and brown in the temperate belt of the northern hemisphere, gray-cinnamon and typical sierozems in the subtropical belt, and red-brown in the tropical belt. The landscapes of these zones have a sparse vegetative cover, often in a mosaic pattern. Grass and wormwood predominate in Eurasia and perennial grasses and shrubs on the other continents. The semidesert zones are used primarily for the grazing of livestock. Regularly recurring harvests are possible only with irrigation.