Temperate grasslands of the world

Topic: World Physical Features and Natural Regions · NCERT: Beyond NCERT

Meaning

Temperate grasslands are wide, mostly treeless lands covered with grass. They lie in the mid-latitudes, about 30°–55° N and S. Most of them are deep in the interiors of continents, far from the sea. They get only 25–75 cm of rain a year and have cold winters. The main ones are the Prairies, Pampas, Steppes, Velds, Downs, Canterbury Plains and Puszta.

They matter because their fertile black soils and big machine-run farms grow most of the world's traded wheat and maize. A drought, war or price shock in these lands raises food prices across the world.

Explanation

Why grass grows here and not forest

• Distance from the sea
• These lands are far from the ocean.
• Moist sea winds lose most of their water before they reach them.

• This gives a continental climate: hot, short summers, very cold winters and a wide yearly range of temperature.

• Rainfall pattern

• Rainfall is 25–75 cm a year.

• Most of it falls in spring and early summer, often as convectional showers (short, heavy showers from rising warm air).

• Climate class: in the Köppen scheme (a way of grouping world climates by temperature and rainfall), the drier edges fall under BSk. BSk means a cold, semi-arid steppe climate.

• Why there are so few trees
• Low rain: there is not enough water for deep-rooted trees.
• Frost: hard winters kill young trees.
• Fire: dry grass burns often. Grass grows back from its roots, but tree seedlings die.

• Grazing: wild animals such as the bison, and later cattle and sheep, eat young shoots.

• Vegetation: tall grass grows in the wetter parts and short grass in the drier parts. Trees grow only along rivers.

Chernozem: the black soil of the grasslands

• Chernozem is Russian for "black earth". It is a deep soil with a thick black top layer rich in humus (rotted plant matter). It is among the most fertile soils in the world [2].
• Conditions it needs: 450–600 mm of rain a year, mostly in spring or early summer, with cold winters and short, hot summers [2].
• How it forms
• Grass roots die every year and add a lot of humus to the soil.
• Low rain means little leaching (water washing nutrients down and out of the soil).

• Calcium and humus therefore stay in the top layer. The soil becomes black and crumbly.

• Spread: about 230 million hectares worldwide, mainly in the steppes of Eurasia and the plains of North America [2].

• Chestnut soils are found at the drier edges.

How people use these lands

• Extensive commercial grain cultivation (very large, machine-run farms that grow grain, mainly wheat, for sale)
• The land is huge and workers are few, so tractors and combine harvesters do the work.
• Low yield per hectare: each hectare gets little fertiliser and labour.
• High yield per worker: one farmer with machines handles hundreds of hectares.

• Winter wheat is grown in milder areas and spring wheat in colder areas. The harvest season is the main limit.

• Livestock ranching (keeping large herds of cattle or sheep on big fenced farms called ranches) for meat, wool and hides. It is common in the drier parts that are not good for ploughing.

• Railways opened these lands
• Trans-continental railways carried settlers in and took grain out to the ports.
• Without them, the interiors had no route to world markets.

Misuse: when the grass is ploughed away

• Dust Bowl, USA (1930s)
• Cause: farmers ploughed up the prairie grass to plant dryland wheat. Rising demand for wheat led to millions more acres being ploughed [3].
• Trigger: a severe drought hit the south-western Great Plains between 1930 and 1940 [3]. NASA research links it to unusual tropical sea-surface temperatures, made worse by land–air feedback [4].

• Result: the bare soil blew away in dust storms, some of which reached the Atlantic Ocean. About 400,000 people left the Great Plains [3][5].

• Virgin Lands campaign, USSR

• A Soviet plan under Nikita Khrushchev. It started in 1953 and was officially launched in March 1954. It ploughed up the grasslands of northern Kazakhstan and western Siberia for wheat, worked by Slavic settlers [6].
• Grain output rose at first. Over the following decades, soil erosion led to an ecological disaster [6].

Where it occurs

Grassland	Where	Key facts
Prairies	USA and Canada. Interior plains east of the Rockies. Canada's Prairie Provinces are Alberta, Saskatchewan and Manitoba	The "wheat basket" of the world. Spring wheat in the colder north (Canada, North Dakota), winter wheat in the milder south (Kansas), maize on the wetter eastern side. Chinook wind
Pampas	Argentina and Uruguay, around the Rio de la Plata estuary	Wheat, alfalfa (a fodder crop for cattle) and beef from big ranch-farms called estancias. South America's densest rail network, spreading out from Buenos Aires. Refrigerated ships (from the late 19th century) took chilled beef to Europe
Steppes	Eurasia, from Ukraine across southern Russia and Kazakhstan to Mongolia	Black-earth wheat belt. Wheat goes out through Black Sea ports such as Odesa. Home of pastoral nomads (herders who move with their horses, sheep and camels to find grass), such as the Kazakhs and Mongols
Velds	South Africa. The high veld is about 1,200–1,800 m high, around Johannesburg and Pretoria	High altitude keeps summers mild even at about 26° S. Rain falls in summer. Maize, wheat, merino sheep. Gold of the Witwatersrand
Downs	South-eastern Australia, mainly the Murray-Darling basin (New South Wales and Victoria)	Wheat and merino sheep. Stock is watered from artesian wells of the Great Artesian Basin
Canterbury Plains	Eastern South Island, New Zealand, in the rain shadow of the Southern Alps	Grain and sheep. Frozen Canterbury lamb is exported. Main town: Christchurch
Puszta	Hungary, the Great Hungarian Plain in the middle Danube basin	Wheat and maize. It was once grazing land for cattle and horses

• Chinook (Prairies): a warm, dry wind that blows down the eastern slopes of the Rockies in winter and spring.
• Moist air rises over the Rockies, cools and drops its rain or snow on the western side.
• The dry air sinks down the eastern side and warms up as it is squeezed.

• It can melt snow in hours, so it is called the "snow eater". This clears pastures for grazing and allows early sowing.

• Rain shadow (Canterbury): the dry side of a mountain range.

• Moist westerly winds from the Tasman Sea rise over the Southern Alps and drop their rain on the west coast.

• The dry air comes down on the east side, so grass grows there and not forest.

• Artesian well (Downs): a well where water rises by itself under pressure. The water-bearing rock layer is fed by rain on higher ground far away. The water is often too salty for crops, so it is used mainly for sheep and cattle.

• India: none of the major temperate grasslands lie in India. India's dry lands in Rajasthan and the Deccan can still learn from the Dust Bowl and the Virgin Lands campaign.

Don't confuse with

• Tropical grasslands (Savanna in Africa, Llanos in the Orinoco basin of Venezuela and Colombia, Campos in the Brazilian Highlands): these are hot all year, have a wet and a dry season, and have tall grass with scattered trees. Temperate grasslands have cold winters and short grass.
• Mediterranean lands (Köppen Cs): these lie on the western sides of continents at about 30°–45° and get rain in winter from the westerlies. Temperate grasslands lie in continental interiors and get rain in spring and early summer.
• Chinook vs Foehn: both are warm, dry winds that blow down mountain slopes. The Chinook blows on the eastern Rockies (Prairies). The Foehn blows in the Alps.
• Velds vs Pampas: the Velds are a high plateau (high veld about 1,200–1,800 m) in South Africa. The Pampas are flat lowlands around the Rio de la Plata in Argentina and Uruguay.

Prelims Hooks

• Grassland and country pairs: Pampas → Argentina/Uruguay, Velds → South Africa, Downs → Australia, Canterbury → New Zealand, Puszta → Hungary, Steppes → Ukraine to Mongolia, Prairies → USA/Canada.
• Trap: the Llanos, Campos and Savanna are tropical grasslands, not temperate ones.
• Chernozem ("black earth") is the soil of the Steppes, Prairies and Pampas. It forms under 450–600 mm of spring and early-summer rain with cold winters [2].
• Extensive grain farming means low yield per hectare but high yield per worker.
• The Black Sea Grain Initiative (July 2022) was brokered by the UN and Türkiye and ran until July 2023. It moved nearly 33 million tonnes of food to 45 countries. Maize (over 16.8 million tonnes) was the largest export, not wheat (8.9 million tonnes). China was the largest buyer, at about 8 million tonnes [1].
• The Canterbury Plains are dry because of the rain shadow of the Southern Alps. The Witwatersrand gold field lies in the high veld. The Great Artesian Basin waters stock on the Downs.

Mains Points

• Grasslands as world breadbaskets (GS-I/GS-III)
• Flat land, fertile chernozem, machine-run farms and railways to the ports give these lands a large grain surplus for export.

• The world depends on only a few such regions, so the food supply is fragile. When Russia's 2022 invasion blocked Ukraine's Black Sea ports, world grain prices jumped. Food-importing countries in Africa and West Asia were hit hard. About 40% of the wheat shipped under the Black Sea Grain Initiative went to low- and lower-middle-income countries [1].

• Land degradation from misuse (GS-III)

• The Dust Bowl in the 1930s USA [3][5] and the Virgin Lands campaign in Kazakhstan [6] show what happens when semi-arid grassland is ploughed without soil conservation: wind erosion, crop failure and people leaving the land. Climate change is expected to make such risks worse.

• Responses: keep grass cover, plant shelter belts (rows of trees that break the wind), use contour ploughing (ploughing across a slope, not up and down it) and match farming to rainfall. These are direct lessons for India's dry lands in Rajasthan and the Deccan.

• Distribution logic (GS-I)

• Temperate grasslands lie in continental interiors, or in rain shadows such as Canterbury, where sea winds bring little moisture and rain falls mainly in spring and early summer.
• Mediterranean lands, at similar latitudes, lie on west coasts and get winter rain. Both patterns come from distance from the sea and the seasonal shift of the pressure belts.

Related concepts

• Prairies
• Pampas
• Steppes
• Velds
• Downs
• Canterbury Plains

Read more

• Natural regions II: temperate grasslands and Mediterranean lands