Semidesert Zones of Subtropical Belts

natural zones in the subtropical belts of the northern and southern hemispheres where semidesert landscapes predominate. These zones usually do not form a solid band, but are characteristic only of highlands and some mountains where they often constitute a vertical zone intermediate between submontane deserts and mountain steppes. Such semidesert zones are found in the mountains of the Iranian Plateau, western Asia, and North Africa; the Rocky Mountains in North America; the Flinders Range in Australia; the Karroo Plateau in South Africa; and the eastern slopes and foothills of the Andes in South America.

The semidesert zones in subtropical belts have a continental climate with hot summers (20°–25°C) and cool winters with occasional snowfall (in the mountains the temperature sometimes drops to 0°C). The annual radiation balance is 2.1–3.1 megajoules per sq m, or 50–75 kilocalories per sq cm. Everywhere the annual precipitation exceeds 200 mm. The vegetation often consists of wormwood and grass, growing on gravelly sierozems or gray-cinnamonic soils. In the North American se-mideserts the plant cover usually includes cactuses, and on the African plateau and in South America shrub formations are widespread. Desert and mountain fauna predominate. The semidesert zones of the subtropical belts are mostly used for pasture. On irrigated land there is intensive farming and fruit growing.