Steppe Climate – Temperate Continental Climate
- Bordering the deserts, away from the Mediterranean regions & in the interiors of the continent are the Temperate grasslands
- Feature semi-arid or steppe climate, which lies between the tropics & Polar Regions.
- Though they lie in the westerlies wind belt, they are so remote from maritime influence that the grasslands are practically treeless.
- Grass are generally distinct in natural vegetation as those lie in S-Hemisphere have a much moderate climate due to coastal effects of the seas & warm currents alongside
- Whereas grasslands in N-Hemisphere are comparatively warmer in summers & colder in winters as they are entirely continental.
- In Eurasia, they are called Steppes, which stretches eastward from the shores of Baltic Sea across the Great Russian plains, to the foothills of Altai Mountains, for approx. 2000 miles
- In isolated sections of Hungary & Mongolian-Manchurian region, they are known as Pustaz
- In North America, the grasslands are quite extensive & known as Prairies, lying between foothills of Rockies & the Great lakes astride American – Canada border
- In the southern hemisphere, due to the narrowness of temperate portions of southern continents, grasslands are rather restricted & less continental
- In case of Pampas of Argentina & Uruguay, the grasslands extend right to the sea & enjoy much maritime influence
- In South Africa, the grasslands are sandwiched between the Drakensberg & Kalahari deserts; & are further divided into the more tropical Bush Veld in the north, & more temperate High Veld in the south
- In Australia, the grasslands are better known as Downs & are found in Murray-Darling basin of southern Australia
- In northern hemisphere, they lie in the heart of continents & thus have little maritime influence
- Hence climate is continental with extremes of temperature.
- Summers are very warm, approx. 25* C, with winters are chilling cold, with well below freezing point viz. approx. – 20*C
- Hence have high annual range of temperature
- In contrast, in southern hemisphere, climate is never severe, with mild winters of ~ 10* C & warm summers with ~ 20* C, due to the maritime effect of the coasts
- Hence annual range of temperature is way less than that in northern hemisphere steppes.
- Annual precipitation in N – Hemisphere has a mean annual of approx. 50 Cm, with majority of rainfall in summers from convectional sources.
- Winter rainfall of approx. 25 mm/ month is occasional by depressions of the westerlies & in form of snow.
- Due to maritime influence in southern hemisphere, mean annual rainfall always averages more than 50 cm, mainly due to warm ocean currents that wash the shores of steppe lands.
- On the eastern slopes of the Rockies in Canada & USA, a local wind similar to Fohn (Switz), called Chinook, comes in south west direction to the Prairies, descending from the Rockies. It is a hot wind that rises the temperature & melts snow covered pastures, generally in winters & early springs, hence frequent chinook means mild winters in the region.
Natural Vegetation of Steppe
- Natural vegetation of steppes is generally referred as temperate grasslands, differing only in density & quality of grass.
- Their greatest difference from tropical savannas is that steppes are practically treeless & grasses are much shorter.
- Regions in N – Hemisphere, where the rainfall averages above 50 cm, the grasses are tall, fresh & nutritious & are better described as long prairie grass
- Examples include North America, Rich black earth of Russia –Ukraine & better watered areas of Asiatic steppe.
- Where the rainfall is light, less than 50 cm, or the soil is poor, as in continental interiors of Asia, the short steppe type of grass prevails.
- The grasses are not only shorter but also wiry & sparse, often found in discontinuous clumps, with bare soil exposed between them.
- The climatic requirement of grass are quite different from trees as they require less moisture than trees & an annual precipitation of approx. 25 – 50 cm is adequate.
- Their growth is not abruptly checked by summer drought & winter cold as they lie dormant throughout this period & sprout instantly as soon as temperature is moist & warm again.
- Trees are very scarce in steppes, because of the scanty rainfall, long droughts & severe winters; with long rolling plains of endless grass.
- Poleward, an increase in precipitation gives rise to a transition zone of wooded steppes where some conifers gradually appear, but are very scattered & few in number.
- Towards the equator, the steppe grass becomes shorter & sparser, till it merges into desert with thorny scrub.
Agricultural developments of Steppe
- Grasslands have been ploughed up for extensive mechanized wheat cultivation & are termed as granaries of the world.
- Beside wheat, maize is also increasingly cultivated, mainly in warmer & wetter areas.
- Farms are extensively long, hence due to less attention & high mechanization, average yield per acre is low, but the yield per man is very high
- Hence grasslands of mid latitudes produce greatest exporters of wheat in the world.
- The tufted grasses have been replaced by more nutritious lucerne & alfalfa grass for cattle & ship rearing.
Natural conditions suit animal farming & with the introduction of more nutritious grass & refrigerated ships, temperate grasslands became major pastoral regions, exporting large quantities of beef, mutton, wool, milk, butter, cheese & other dairy products viz. Pampas became lead exporter of beef & Australia became world’s leading wool exporter.