Ecology of Rajasthan Desert

Ecology of Rajasthan Desert:-

Introduction:-

> Dry landmass called as the Desert. 

> Earth has numerous land areas covered by deserts. 

> Among all the terrestrial ecosystems, deserts are very typical landforms due to their unique ecological conditions. 

> Desert and near-desert areas cover nearly 1/3 of the land surface of the globe. 

> Deserts alone covers about 1/7 of the land surface. 

> We normally call deserts as “sand seas or oceans of sands”. 

Rajasthan desert or Thar desert or the great indian desert:-

1. Size and Location:-

> Thar Desert, also called great Indian desert , located on the Indian subcontinent. It is bounded by Aravali range in east and located partly in Rajasthan state, northwestern India, and partly in Punjab and Sindh (Sind) provinces, eastern Pakistan 

> The desert stretches its area of 238,254 km² (77,000 sq mi). 

> It is considered to be the 20th largest desert and 9th largest subtropical desert of the world. 

> 27.4695° N, 70.6217° E (Coordinates of the centre of the desert)

2. Physical Features:-

> The Indian desert lies on the western edge of the hills of Aravalli. 

> It is an undulating sandy plain surrounded by dunes of sand. 

> Very low rainfall, below 150 mm per year, occurs in this area. 

> With poor vegetation cover, it has an arid atmosphere. 

> During the rainy season, streams emerge. They vanish into the sand shortly after, as they do not have enough water. 

> Barchans (crescent-shaped dunes) cover larger areas, but along the Indo Pakistan border, longitudinal dunes are becoming more prevalent.

3. Rivers and canals:- 

> There is one and only one river in thar Desert. That is ‘Luni’. 

> The Luni is the largest river in the Thar Desert of northwest India. 

> Luni originates in the Pushkar valley of the Aravalli Range, near Ajmer, passes through the southeastern portion of the Thar Desert, and ends in the marshy lands of Rann of Kutch in Gujarat, after travelling a distance of 495 kilometres. 

> Indra Gandi Canal is drawn from satluj to the desert for peoples. 

4. Climate:-

> The amount of annual rainfall in the desert is generally low, ranging from about 4 inches (100 mm) or less in the west to about 20 inches (500 mm) in the east. 

> Precipitation amounts fluctuate widely from year to year. 

> About 90 percent of the total annual rainfall occurs during the season of the southwest monsoon, from July to September (see also Indian monsoon). 

> During other seasons the prevailing wind is the dry northeast monsoon. 

> May and June are the hottest months of the year, with temperatures rising to 122 °F (50 °C). 

> During January, the coldest month, the mean minimum temperature ranges between 41 and 50 °F (5 and 10 °C), and frost is frequent. 

> Dust storms and dust-raising winds, often blowing with velocities of 87 to 93 miles (140 to 150 km) per hour, are common in May and June 

> It has a hot arid climate with unfertile sand. It has extreme climate. 

> It is very hot in day and very cold in night. 

> Due to high temperature, pressure is high in this area.

5. Natural vegetation and wildlife:-

> The desert vegetation is mostly herbaceous or stunted scrub; drought-resistant trees occasionally dot the landscape, especially in the east. 

> On the hills, gum arabic acacia and euphorbia may be found. 

> The khajri (or khejri) tree (Prosopis cineraria) grows throughout the plains. 

> The thickly populated grasslands support blackbucks, chikara (gazelles), and some feathered game, notably francolins (partridges) and quail. 

> Among the migratory birds, sand grouse, ducks, and geese are common. The desert is also the home of the endangered great bustard. 

> The ship of the desert ‘camel’ found here useful for travel, milk, fibre and has a great significance.

6. Flora:-

> These adaptations in general are of two types, having two distinct objects in view: to enable the

plant to obtain water, and to retain it when obtained.

> The bulk of the vegetation consists of a kind of scrub made up of shrubs and perennial herbs, capable of great drought resistance.

> There are a few trees and these are stunted and generally thorny or prickly, thus protecting themselves against plaint feeding animals.

> The proper desert plants may be divided into two main groups.

a. Depending directly upon on rain

b. Depending on the presence of subterranean water

a. Depending directly upon on rain:- Two types - 

i. Ephemerals

ii. Rain perennials

i. Ephemerals:- They are delicate annuals, apparently free from any xerophilous adaptations, having

slender stems and root-systems and often large flowers. They appear almost immediately after

rain, develop flowers and fruits in an incredibly short time, and die as soon as the surface layer of

the soil dries up.

ii. Rain perennials:- They are visible above the ground only during the rainy season, but have a perennial underground stem.

b. Depending on the presence of subterranean water:-

i. By far the largest number of indigenous plants are capable of absorbing water from deep below the surface of the ground by means of a well- developed root systems the main part of which generally consists of a slender, woody tap root of extraordinary length.

ii. Generally, various other xerophilous adaptations are resorted to such as reduced leaves, thick

hairy growth, succulence, coatings of wax, thick cuticle, protected stomata, etc., all having for their

object of reduction of transpiration.