Baring the biodiverse heart of the Thar desert

  • August 7, 2023
  • Posted by: OptimizeIAS Team
  • Category: DPN Topics
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Baring the biodiverse heart of the Thar desert

Subject: Environment

Section: Ecosystem

Context:

  • The Thar, one of the most populated deserts in the world, has long been perceived as a barren wasteland. However, a recent study by IIT-Jodhpur shows that this arid ecosystem harbours remarkable biodiversity, containing four distinct ecoregions.

Details:

  • The study used community science, specifically crowdsourced bird data from the online resource eBird, to assess the biota and delineate the ecoregions.
  • Crowdsourcing data through citizen science programmes is a cost-effective means of covering a wide spatial area.

Four ecoregions of Thar desert:

  1. Eastern Thar, comprising nine districts, is marked by the Aravalli region and the eastern agro-industrial region.
  2. Western Thar, with five districts, includes the western arid regions.
  3. The ‘transitional zone’ consists of 13 districts on either side of the Aravalli range.
  4. The ‘cultivated zone’, with six districts scattered across the Thar, was identified as an evolving zone due to anthropogenic activities and a higher risk of habitat fragmentation, posing a concern for near-threatened species.

Bird methodology:

  • Birds have been found to be valuable indicators of ecosystem functions, making them essential to ecological research.
  • A total of 492 bird species were recorded across 33 districts in Rajasthan, which collectively make up nearly 70 per cent of Thar.
  • The birds serve as a representative biota for inferring shifts in ecoregions, the effect of anthropogenic activities, and the need for ecoregion-based conservation strategies to protect endangered habitats and species.
  • Birds also helped in identifying invasive species and the ecological changes due to climate change or human activities.

Thar desert:

  • The Thar Desert, also known as the Great Indian Desert, is an arid region in the north-western part of the Indian subcontinent that covers an area of3.85 lakh sq km (82,000 sq mi) in India and Pakistan.
  • The roughly 3.85 lakh sq km Thar Desert accounts for about 9 per cent of India’s land area and 2.12 per cent of its fauna — 682 species of flora and 1,195 species of fauna.
  • It is the world’s 20th-largest desert, and the world’s 9th-largest hot subtropical desert.
  • About 85% of the Thar Desert is in India, and about 15% is in Pakistan.
  • The Thar Desert is about 4.56% of the total geographical area of India.
  • More than 60% of the desert lies in the Indian state of Rajasthan; the portion in India also extends into Gujarat, Punjab, and Haryana.
  • The portion in Pakistan extends into the provinces of Sindh and Punjab (the portion in the latter province is referred to as the Cholistan Desert).
  • The Indo-Gangetic Plain lies to the north,west and northeast of the Thar desert,the Rann of Kutch lies to its south, and the Aravali Range borders the desert to the east.
  • Climate:
    • The climate is arid and subtropical. Average temperature varies with season, and extremes can range from near-freezing in the winter to more than 50º C in the summer months.

History of desertification of Thar:

  1. Ice-age desertification:
    • During the Last Glacial Maximum 20,000 before present, an approximately 2,400,000 square kilometers (930,000 sq mi) ice sheet covered the Tibetan Plateau, causing excessive radiative forcinge. the ice in Tibet reflected at least four times more radiation energy per unit area into space than ice at higher latitudes, which further cooled overlying atmosphere at that time.
    • This impacted the regional climate. Without the thermal low pressure caused by the heating, there was no monsoon over the Indian subcontinent.
    • This lack of monsoon caused extensive rainfall over the Sahara, expansion of the Thar Desert, more dust deposited into the Arabian Sea, a lowering of the biotic life zones on the Indian subcontinent, and animals responded to this shift in climate with the Javan rusa deer migrating into India.
  1. Desertification due to drying up of Sarasvati river:
    • 10,000-8,000 years ago a paleo channel of Ghaggar-Hakra River – identified with the paleo Sarasvati River, after confluence with Sutlej flowed into the Nara river – a delta channel of the Indus River, changed its course, leaving the Ghaggar-Hakra as a system of monsoon-fed rivers which did not reach the sea and now ends in the Thar desert.
    • Around 5,000 years ago when the monsoons that fed the rivers diminished further, the Indus Valley Civilisation (IVC) prospered in this area, with the rise of numerous IVC urban sites at Kalibangan (Rajasthan), Banawaliand Rakhigarhi (Haryana), Dholavira and Lothal (Gujarat) along this course.
    • 4,000 years agowhen monsoons diminished even further, the dried-up Harkra become an intermittent river, and the urban Harappan civilisation declined, becoming localized in smaller agricultural communities.

eBird:

  • Launched in: 2002
  • Created by: Cornell Lab of Ornithology
  • eBird is an online database of bird observations providing scientists, researchers and amateur naturalists with real-time data about bird distribution and abundance.
  • Originally restricted to sightings from the Western Hemisphere, the project expanded to include New Zealand in 2008, and again expanded to cover the whole world in June 2010.
  • eBird has been described as an ambitious example of enlisting amateurs to gather data on biodiversity for use in science.
  • eBird is an example of crowdsourcing, and has been hailed as an example of democratizing science, treating citizens as scientists, allowing the public to access and use their own data and the collective data generated by others.
Baring the biodiverse heart of the Thar desert Environment