Climate and Microclimate Changes Influencing the Fauna of the Hot Indian Arid Zone

Abstract

The Indian hot arid zone, situated largely in western Rajasthan and Kachchh of Gujarat, is subjected to frequent droughts and famines causing high stress on flora and fauna. Annual rainfall in the region varies from 100 to 500 mm and air temperatures from −5.0 to 48°C. Soil temperature decreases sharply by 10–20°C from the surface to depths below 20 cm, particularly during the summer months, improving life conditions in the burrows of rodents, snakes, reptiles, insects, etc. Drought occurrence in the Thar region has amounted to 47–62% of the last century, causing widespread economic loss due to crop failures, and promoting a substantial migration of human and livestock populations in search of better living conditions. The high densities of human and livestock populations in the region further aggravate the depletion of natural resources and impact on biodiversity. The introduction of irrigation to the Thar Desert via the construction of the Indira Gandhi Canal has resulted in substantial man-induced changes in the microclimate, flora and fauna of the area, due to the conversion of grasslands into irrigated cultivated lands. Notably, extensive long-term irrigation has not only increased vegetation in Sri Ganganagar but it has also improved the rainfall by 1.2 mm/year. Where irrigation has been introduced less extensively in Jaisalmer District, however, only a slight increase in annual rainfall (0.2 mm/year) has been observed, while there has been no significant change in long-term rainfall in irrigation-free Bhuj. Land-use changes continue to influence the microclimate, rainfall patterns and fauna of the Thar region.