Daily Quiz: UPSC Prelims Marathon – February 22, 2019

Photoperiod refers to the time that a plant or animal is exposed to light in a 24-hour period. Hibernation, Breeding time and Migration of living organisms in different habitat is influenced by the Photoperiod.

Elfin Forest: Elfin forest is also known as Dwarf forest or pygmy forest. It is a rare ecosystem featuring miniature trees, inhabited by small species of fauna such as rodents and lizards. They are usually located at high elevations, under conditions of sufficient air humidity but poor soil.

There are two main dwarf forest ecosystem types, involving different species and environmental characteristics: coastal temperate and montane tropical regions. Temperate coastal dwarf forest is common for parts of Southern California.

Sclerophyll Forest: Sclerophyll is a type of vegetation that has hard leaves, short internodes (the distance between leaves along the stem) and leaf orientation parallel or oblique to direct sunlight. The sclerophyll leaves have three leaf stress traits used to cope with hot and dry summer.

This type of forest is found in parts of Australia, in the Mediterranean forests and parts of south Africa.

Alpine Forests: Alpine Forests occur at altitudes ranging between 2,900 to 3,500 metres. These forests can be divided into: (1) sub-alpine; (2) moist alpine scrub and (3) dry alpine scrub. It is a mixture of coniferous and broad-leaved trees in which the coniferous trees attain a height of about 30 m while the broad leaved trees reach only 10 m. Fir, spruce, rhododendron, etc. are important species.

Montane Forest: Montane Forest grows at a height of 1800 to 3000 m above sea level. Mean annual rainfall is 150 cm to 300 cm. The trunks have large girth. Branches are clothed with mosses, ferns and other epiphytes. The trees rarely achieve a height of more than 6 metres. Deodar, Chilauni, Indian chestnut, birch, plum, machilus, cinnamomum, litsea, magnolia, blue pine, oak, hemlock, etc. are important species.

In India, Montane Forest is found in higher hills of Tamil Nadu and Kerala, in the Eastern Himalayan region.

The major peninsular rivers from north to south direction:

Narmada, Tapi, Godavari, Krishna, Penneru, Palar, Kaveri and Periyar.

Statement 1 is incorrect.

When the Monsoon trough keeps on moving northward or southward, it results spatial distribution of rainfall. It does not stop the rain or no break in Monsoon occurs due to this.

Statement 2 is correct.

Over the west coast the dry spells are associated with days when winds blow parallel to the coast.

Statement 3 is incorrect.

When the axis of the monsoon trough lies over the plains, rainfall is good in these parts (plains).

During the south-west monsoon period after having rains for a few days, if rain fails to occur for one or more weeks, it is known as break in the monsoon. These dry spells are quite common during the rainy season.

These breaks in the different regions are due to different reasons:

• When the Monsoon trough shifts to the foothills of Himalayas, which leads to sharp decrease in rainfall over most parts of the country but increase along the Himalayas and parts of Northeast India and Southern Peninsula.
• When the monsoons become weak, generally during July and August. Then, rainfall practically ceases over the country outside the Himalayan belt and southeast peninsula.
• The breaks are believed to be brought about by the northward shifting of the monsoon trough (minimum low-pressure cell in ITCZ). The axis of the trough lies at the foothills of the Himalayas during the break period.

Peaty Soils are found in the areas of heavy rainfall and high humidity, where there is a good growth of vegetation. Thus, large quantity of dead organic matter accumulates in these areas, and this gives a rich humus and organic content to the soil.

It is arid soil not Peaty which develops in the areas where salt content is very high.

Organic matter in Peaty Soils may go even up to 40-50 per cent.

These soils are normally heavy and black in colour. At many places, they are alkaline also.

These soils occur widely in the northern part of Bihar, southern part of Uttarakhand and the coastal areas of West Bengal, Orissa and Tamil Nadu.

The river Cauvery thrice forks into two streams and reunites a few miles farther on, and forms the islands of Sivasamudram, Sringapattanam and Srirangam in the eastern part of Tamilnadu.

Sudden rise of temperature and low pressure over the Indian Sub-continent during summer season pulls air from the Arabian Sea and Bay of Bengal. It is the South-West Monsoon, which brings rainfall in India.