Shankar IAS Test: Terrestrial Ecosystem- 1 - UPSC MCQ

• Tundra means a “barren land” since they are found where environmental conditions are very severe. There are two types of tundra - arctic and alpine.

• Distribution: Arctic tundra extends as a continuous belt below the polar ice cap and above the tree line in the northern hemisphere. It occupies the northern fringe of Canada, Alaska, European Russia, Siberia and the island group of the Arctic Ocean. On the South Pole, tundra is very small since most of it is covered by the ocean.

• They are protected from chillness by the presence of thick cuticle and epidermal hair. Mammals of the tundra region have large body size, small tail and small ear to avoid the loss of heat from the surface.

Temperate evergreen forest:

• Parts of the world that have the Mediterranean type of climate are characterised by warm, dry summers and cool, moist winters.

• These are commonly inhabited by low broad-leaved evergreen trees.

• Fire is an important hazardous factor in this ecosystem and the adaptation of the plants enables them to regenerate quickly after being burnt.

• In the North, Montane wet temperate forests are found in the region to the east of Nepal into Arunachal Pradesh.

• There are three layers of forests: the higher layer has mainly coniferous, the middle layer has deciduous trees such as the oak and the lowest layer is covered by rhododendron and Champa.

• In the South, it is found in parts of the Nilgiri Hills, the higher reaches of Kerala.

• The forests in the northern region are denser than in the South. Rhododendrons and a variety of ground flora can be found here.

• In this practice a patch of land is cleared, vegetation is burned and the ash is mixed with the soil thus adding nutrients to the soil.

• This patch of land is used for raising crops for two to three years, and the yield is modest. Then this area is abandoned and is left to recover its fertility, and the same practice is repeated elsewhere on a fresh piece of land.

Both the statements are correct.

• The grasslands are found where rainfall is about 25-75 cm per year, not enough to support a forest, but more than that of a true desert.

• Typical grasslands are vegetation formations that are generally found in temperate climates. In India, they are found mainly in the high Himalayas.

• Semi-arid zone: It covers the northern portion of Gujarat, Rajasthan (excluding Aravallis), western Uttar Pradesh, Delhi and Punjab. The topography is broken up by hill spurs and dunes.

• Dry sub-humid zone: It covers the whole of peninsular India (except Nilgiri).

• Moist sub-humid zone: It covers the Ganga alluvial plain in Northern India. The topography is level, low lying and ill-drained.

• Humid montane regions: This extends to the humid montane regions and moist sub-humid areas of Assam, Manipur, West Bengal, Uttar Pradesh, Punjab, Himachal Pradesh and Jammu and Kashmir. The savanna is derived from the humid forests on account of shifting cultivation and sheep grazing.

• Due to heavy grazing pressure, the quality of grasslands deteriorates rapidly, the mulch cover of the soil reduces, microclimate becomes drier and is readily invaded by xerophytic plants and burrowing animals.

• Due to the absence of humus cover, the mineral soil surface is heavily trampled, when wet it produces puddling of the surface layer. In turn, it reduces the infiltration of water into the soil and accelerates run off, resulting in soft erosion.

The animals are physiologically and behaviorally adapted to desert conditions. They are fast runners, they are nocturnal in habit to avoid the sun’s heat during day time, they conserve water by excreting concentrated urine, animals and birds usually have long legs to keep the body away from the hot ground.

Thar desert: The climate of this region is characterized by excessive drought, the rainfall being scanty and irregular.

The winter rains of northern India rarely penetrate the region. The relative humidity of the atmosphere is always low. The climate is hostile to all vegetation, only plants and animals possessing special adaptations being able to establish themselves.

• It is the destruction of the biological potential of the land which can ultimately lead to desert-like conditions.

• In arid and semiarid regions, the restoration of the fragile ecosystem is very slow, and issues like deforestation, mining enhances desertification.

• Desertification is the main problem faced by desert adjoining areas, which stretches across parts of Rajasthan, Gujarat, Punjab and Haryana.