Grasslands are the large continuous regions having different types of grasses with either no trees or negligible presence of trees. These grasslands of the world are one of the largest biomes of the world. Steppe is the largest grassland in the world.
Types of Grasslands
There are two types of grasslands i.e. temperate grasslands and the tropical grasslands.
1. Temperate Grasslands
Temperate Grasslands are also known as the true grasslands as the grasses are dense with negligible presence of trees. The height of these grasses vary from 50 centimeters to 2.5 meters.
- Location: The temperate grasslands are primarily located between 30 to 60 degree latitudes in interior parts of the continents in the northern and southern hemisphere.
- Climate: The temperate grasslands grow in the cold continental climate (-40°C to 22°C) with an average rainfall of approximately 75-100 centimeters. This region remains under the impact of westerly winds but due to interior location, the temperate grasslands receive low annual rainfall. The temperate grasslands of the southern hemisphere lie on the eastern margins of continents which are under the influence of warm ocean currents. Hence, there is availability of more moisture to the temperate grasslands of the south hemisphere than the north hemisphere.
- Soil: The temperate grasses flourish on chernozem or black soil which are rich in humus, phosphorus and ammonia. Since this soil can absorb a lot of water, the grasses do not die out during the drier part of the year. In the fringes of temperate grasslands, the dry grasses grow on the chestnut soil.
- Important Temperate Grasslands: The most important and large grasslands of the world are (See in Fig. 1):
- Steppes in Eurasia
- Prairies in North America
- Pampas in Argentina
- Velds in South Africa
- Downs in Australia
- Pustaz in Hungary
- Canterbury in New Zealand and
- Manchuria grasslands in China
Flora in Temperate Grasslands
- The important types of grasses which grow in temperate grasslands are festuca and stipa in Steppes; june grass, blue gramma, buffalo grass and purple needle grass in Prairies; themeda in Velds; kangaroo grass and danthonia in Downs, tussock grasses (festuca and poa) in Canterbury. The main types of flowers in temperate grasslands are wild indigos, blazing stars, asters, goldenrods and coneflowers.
Fauna in Temperate Grasslands
- Due to availability of herbaceous grasses, a lot of species of large herbivore animals such as bison, horse, deer, small underground animals such as rabbits, rodents etc. and small carnivore animals such as prairie dogs, foxes, jackals etc. thrive in these grasslands. Since, the temperate grasslands are not particularly tall like Savanna grasslands, the large carnivore animals do not get cover during hunting. Hence, large carnivore animals are not present in temperate grasslands. Some flightless birds like emu, ostrich and cassowary also thrive in these grasslands.
2. Tropical Grasslands
Tropical grasslands are also referred to as savannah grasslands. These are not true grasslands because there are plenty of intermittent trees in these grasslands.
- Location: Tropical grasslands are located in the periphery of the equatorial forest region towards the eastern coasts of continents. It is a transition zone between equatorial rainforests and the completely dry deserts.
- The tropical grasslands fall within the monsoon climatic zone and experience seasonal rainfall in summer and remain mostly cold and dry during winters. The influence of warm currents on the eastern coasts of continents in tropical zones along with onshore monsoon winds provide more moisture and rainfall to tropical grasslands than the temperate grasslands. Therefore, the tropical grasslands are so tall that they can hide large animals like elephants and giraffes within them.
- Soil: Tropical grasslands grow on the soils of different types i.e. alluvial soil, black soil, red soil, chestnut soil etc.
- Important Tropical Grasslands: The important tropical grasslands of the world are (see fig. 1):
- Llanos in Venezuela
- South American Savannah
- African Savannah
- Indian Savannah
- Australian Savannah
Flora in Tropical Grasslands
- There are three layers of vegetation in the tropical grasslands.
- The ground layer contains the different varieties of grasses which attain a height of upto 5 meters. The important species of grasses are Hyperrhenia or elephant grass, Panicum, Andropogon, Pennisetum etc.
- The middle layer contains the shrubs ranging from 6-12 meters in height.
- The top layer includes the deciduous trees of various species.
Fauna in Tropical Grasslands
- The tropical grasslands have the maximum biological diversity among all the biomes of the earth. The animals in these grasslands have grown large in size as a part of evolution to move through thick and tall grasses. Hundreds of species of herbivore and carnivore animals in these biomes i.e. deer, zebra, wildebeest, giraffe, elephants, lions, hyenas, cheetahs, leopards etc.
Human Impact on Grasslands
Human beings are one of the largest factors of change in natural order in the contemporary world. We have trespassed on the large swathes of natural landscape which lead to extinction of plants and animals. Similarly, the humans have cleared huge amounts of lands for agriculture, habitation, mining and manufacturing.
- The humans have wiped out most of the population of indigenous animals from grasslands i.e. bison, wild horses, rodents, foxes etc.
- With the use of chemical fertilizers, pesticides and weedicide, the soil and water table is polluted.
- In fact, the tropical grasslands are not even true grasslands because it is the humans who have cleared the vast swathes of tropical forest which has lead to emergence of tropical grasslands.
- Grasslands are practically the basket of grains for the world with no signs of the original natural landscape.
To conclude, we can argue that the grasslands are the largest regions with fertile plains but humans have cleared these plains for agricultural and economic purposes leading to degradation of these biomes. We must conserve the remaining grasslands for preservation of climate. We must make laws, establish institutions and enforce these laws for conservation of the natural grassland ecosystem.
Kulwinder Singh is an alumni of Jawaharlal Nehru University, New Delhi and working as Assistant Professor of Geography at Pt. C.L.S. Government College, Kurukshetra University. He is a passionate teacher and avid learner.