Thar Desert ecosystem
The Thar Desert, also known as the Great Indian Desert, spans approximately 172,202 square miles across western India, eastern Pakistan, and southern Afghanistan, making it a significant yet not the largest desert globally. Characterized by a tropical desert climate, the region experiences extremely high temperatures during summer months, with average highs reaching 106°F (41°C). Despite its arid conditions, the Thar is notable for being the most densely populated desert in the world, hosting an average of 83 people per square mile, which is considerably higher than in other deserts.
The ecosystem is rich in biodiversity, influenced by its varied soil types and water availability. The Thar serves as a convergence zone for different biogeographic regions, promoting a diverse avian population with around 250 to 300 bird species recorded. However, ongoing environmental changes, such as the Indira Gandhi Nahar Project, threaten the delicate balance of its ecosystem by altering traditional land use and increasing pressure on habitats.
Vegetation in the Thar primarily consists of thorn and scrub forests, with many plant species providing economic value through fibers, dyes, and medicinal properties. Wildlife is also diverse, with over 50 mammal species, including domesticated camels, which are crucial for transportation in the challenging desert landscape. As climate change and population growth impact the region, conservation efforts are critical to maintain the fragile equilibrium of the Thar Desert ecosystem.
Subject Terms
Thar Desert ecosystem
Category: Desert Biomes.
Geographic Location: Asia.
Summary: The Thar Desert, also called the Great Indian Desert, is one of the smaller deserts in the world, but it is the largest in India, exhibiting a wide variety of habitats and biodiversity.
Deserts are territories that generally receive less than 5 inches (120 millimeters) of rainfall, averaged over more than 30 years. The Thar, also called the Great Indian Desert, includes the arid portions of western India, eastern Pakistan, and southern Afghanistan. It covers an area of about 172,202 square miles (446,000 square kilometers). The Thar Desert is not one of the largest deserts in the world, but it exhibits a wide range of habitats and biodiversity. It is the most thickly populated desert in the world, with an average density of 83 people per 0.4 square mile (1 square kilometer), whereas in other deserts of the world, the average is only seven people per 0.4 square mile (1 square kilometer). The Thar is considered to be an important desert in terms of its location where Palaearctic, Oriental, and Saharan elements of biodiversity are found.
Climate and Water Resources
The Thar area has a tropical desert climate. April, May, and June are the hottest months. The average maximum and minimum temperatures during this period are 106 degrees F (41 degrees C) and 75 degrees F (24 degrees C), respectively, while December, January, and February are the comparatively coldest months, with average maximum and minimum temperatures of 82 degrees F (28 degrees C) and 48 degrees F (9 degrees C).
Rainfall varies from year to year. Most of the rain falls in the monsoon months from June and September, whereas winter rains are insignificant. The Thar Desert of Afghanistan receives annual rainfall of 13 inches (324 millimeters), and some groundwater comes from the Helmand River flowing through this region. The water resources of the Pakistan desert include water of the Indus River and its tributaries, the Kabu, Jhelum, Chenab, Ravi, Beas, and Sutlej. Local rainfall and usable groundwater from the aquifers underlying the plains are the other available water resources. The average annual rainfall in this region is 10 inches (250 millimeters).
The Thar is a transition zone between major wind belts. Midlatitude cyclones produce moderate amounts of winter precipitation in the northern and western portions, while the eastern portion receives its rainfall from the monsoon circulation that dominates the subcontinent in the summer. The monsoon movement of moist air terminates in western India, resulting in light and irregular rainfall in the Thar. Summers are hot and winters warm throughout the area.
For the Thar as a whole, the entire desert consists of level to gently sloping plains broken by some dunes and low, barren hills, interspersed with sandy and medium- and fine-textured depressions or river terraces and floodplains. Stony and gravelly soils are confined to the slopes of the mountains on the south and east, and the plateaus in the northwest.
Biodiversity
The biodiversity of the region is strongly influenced by soil conditions and water availability, with communities varying distinctively among sand, gravel, and rock areas. Despite its comparatively small area, the Thar Desert has high avian diversity thanks to its location on the crossroads of the Palaearctic and Oriental biogeographic regions. As the Thar Desert is not isolated, avian endemism (species found only here) is low. To the west, it is connected through the Sind Plains with the Persian and then the Arabian Deserts; to the northeast, to the Gangetic plains; and to the east, it joins the semiarid biogeographic zone. In the south, it merges with the Rann of Kutch Desert.
Most species of birds of the Thar are widely distributed; a total 250 to 300 species have been reported here overall. This variation is mainly due to the fact that some authors include Kutch, parts of Saurashtra, and the western side of the Aravalli Mountains in the Thar Desert, while others have more a restrictive definition of the desert that includes only nine districts of western Rajasthan and Kutch in Gujarat.
Tremendous changes in the avifaunal structure of the Thar Desert are taking place due to the Indira Gandhi Nahar Project (IGNP), and species never seen here previously are now regularly found near this canal area. However, the project is wreaking havoc with the desert ecosystem by changing the crop pattern and traditional grazing regimes. Also, the desert is being colonized by new people who do not have the same conservation value system that the desert people have always had.
With the canal providing easy availability of water everywhere, unsustainable livestock grazing is taking place, and the famous Sewan grasslands, which have survived for hundreds of years with low grazing pressure, are now under tremendous pressure. These grasslands are the major habitat of the highly endangered great Indian bustard (Ardeotis nigriceps), the winter migrant (Houbara), and the Macqueen’s bustard (Chlamydotis macqueeni).
Other important desert species are the cream-colored courser (Cursorius cursor); greater hoopoe-lark (Alaemon alaudipes); and various species of sandgrouse, raptors, wheatears, larks, pipits, and munias. In the Rann of Kutch of Gujarat, both greater flamingoes (Phoenicopterus roseus) and lesser flamingoes (P. minor) breed when conditions are suitable. These nesting colonies come under increasing pressure due to tourist disturbance, and a large number of nests have been reported to have been destroyed. As the sites of the nesting colonies shift, it is difficult to protect them.
Vegetation
Ecologically, the vegetation of the major part of the region falls in the categories of thorn forest type or scrub forest type. Vegetation in this region is sparse, but a surprisingly large number of plant species exist and have immense economic value. Some of the important plants yielding fiber for cottage industries are Acaccia jacquemontii, Leptadenia pyrotechnica, Saccharum bengalense, S. munja, Calotropis procera, Acacia senegal, and Acacia nilotica. Natural dyes are extracted from Butea monosperma and Lawsonia alba. Citrillus colocynthis and C. lanatus yield nonedible oil for the washing-soap industry.
Famine-food plants that provide grain include Cenchrus biflorus, Panicum turgidum, and P. antidotale. Plants of medicinal value are Plantago ovate and Commiphora wightii. In the extreme west of the region, there is hardly any tree to meet the tired eyes of a traveler except the king of desert trees, the khejri (Prosopis cineraria), which grows only near wells.
In the 2010s and into the 2020s, the growing population coupled with erratic monsoon seasons caused by climate change have reduced the region’s grasslands. Many of the area’s villagers have historically relied on these grasslands to feed their livestock. In 2019, a project sponsored in part by the Indian government, the United Nations, and several non-government organizations, began an effort to restore pastureland near several desert villages.
Wildlife
The Great Indian Desert is fairly rich in fauna. About 38 species of fish occur in the perennial lakes in the desert. In the larger lakes, Crocodilus palustris is fairly abundant, but now its numbers are declining, partly due to the drying of lakes during droughts and partly due to human persecution.
More than 50 mammalian species inhabit the Thar Desert, including large carnivorous flying bats and tiny rodents. The panther (Panthera tigris) is usually associated with hilly regions, but its numbers are also dwindling. Rodents constitute one of the largest animal groups in the region. Among insect pests, the desert locust (Schistocerca gregaria) is the most pernicious destroyer of vegetation.
The inhabiting populations of the region have domesticated the camel (Camelus dromedarius), upon which they are widely dependent for purposes including transportation. The camels in the region are also called the “ships of the desert” because they are the only mode of transportation in the Thar, where human feet and car tires sink into the soft dunes.
Human, animal, and plant desert dwellers are generally well adapted to face the problem of scarcity of water, food, and shelter. An excellent equilibrium has been maintained between the resources available in this area and their use, so that the ecological balance has not been seriously disturbed. But the desert ecosystem is a fragile one, so it has to be handled very carefully in a tender fashion and with great mercy. Slight carelessness, poor planning, and climate change may spoil it to the point of no return.
Bibliography
Baqri, Q. H. and P. L. Kankane. “Deserts: Thar.” In Ecosystems of India, edited by J. R. B. Alfred. Kolkata, India: ENVIS-Zoological Survey of India, 2001.
Champion, H. G. and S. K. Seth. A Revised Survey of the Forest Types of India. Delhi: Manager of Publications, University of Michigan, 1968.
Gupta, R. and I. Prakash. Environmental Analysis of the Thar Desert. Dehradun, India: English Book Depot, 1975.
Mathur, C. M. “Forest Types of Rajasthan.” Indian Forester 86 (1960).
Pardikar, Rishika. “The Destructive ‘Greening’ of the Thar Desert in India.” The Third Pole, 19 Aug. 2020, www.thethirdpole.net/en/nature/the-destructive-greening-of-the-thar-desert-in-india/. Accessed 30 Aug. 2022.
Planning Commission, Government of India. “Report of the Task Force on Grasslands and Deserts.” http://planningcommission.nic.in/aboutus/committee/wrkgrp11/tf11‗grass.pdf.
Tewari, D. N. Desert Ecosystem. Dehradun, India: International Book Distributors, 1994.
Ward, D. The Biology of Deserts. Oxford, UK: Oxford University Press, 2009.
Whitford, W. G. Ecology of Desert Systems. Waltham, MA: Academic Press, 2002.