Passage

Directions for the following 7 (seven) items : Read the following four passages and answer the items that follow. Your answers to these items should be based on the passages only. Passage—1 ‘Desertification’ is a term used to explain a process of decline in the biological productivity of an ecosystem, leading to total loss of productivity. While this phenomenon is often linked to the arid, semi-arid and sub-humid ecosystems, even in the humid tropics, the impact could be most dramatic. Impoverishment of human-impacted terrestrial ecosystems may exhibit itself in a variety of ways : accelerated erosion as in the mountain regions of the country, salinization of land as in the semi-arid and arid ‘green revolution’ areas of the country, e.g., Haryana and western Uttar Pradesh, and site quality decline—a common phenomenon due to general decline in tree cover and monotonous monoculture of rice/wheat across the Indian plains. A major consequence of deforestation is that it relates to adverse alterations in the hydrology and related soil and nutrient losses. The consequences of deforestation invariably arise out of site degradation through erosive losses. Tropical Asia, Africa and South America have the highest levels of erosion. The already high rates for the tropics are increasing at an alarming rate (e.g., through the major river systems—Ganga and Brahmaputra, in the Indian context), due to deforestation and ill-suited land management practices subsequent to forest clearing. In the mountain context, the declining moisture retention of the mountain soils, drying up of the underground springs and smaller rivers in the Himalayan region could be attributed to drastic changes in the forest cover. An indirect consequence is drastic alteration in the upland-lowland interaction, mediated through water. The current concern the tea planter of Assam has is about the damage to tea plantations due to frequent inundation along the flood-plains of Brahmaputra, and the damage to tea plantation and the consequent loss in tea productivity is due to rising level of the river bottom because of siltation and the changing course of the river system. The ultimate consequences of site desertification are soil degradation, alteration in available water and its quality, and the consequent decline in food, fodder and fuelwood yields essential for the economic well-being of rural communities.

Which of the following is/are the correct inference/ inferences that can be made from the passage? 1. Deforestation can cause changes in the course of rivers. 2. Salinization of land takes place due to human activities only. 3. Intense monoculture practice in plains is a major reason for desertification in Tropical Asia, Africa and South America. Select the correct answer using the code given below.

(a) 1 only ✓ UPSC's answer
(b) 1 and 2 only
(c) 2 and 3 only
(d) None of the above is a correct inference

Why the answer is (a)

• Statement 1 is correct because the passage states that deforestation leads to 'adverse alterations in the hydrology,' which logically includes changes in river courses due to altered water flow and erosion.

• Statement 2 is incorrect because the passage links salinization to 'human-impacted terrestrial ecosystems' and 'green revolution' areas, but does not state that it occurs 'only' due to human activities, nor does it exclude natural causes.

• Statement 3 is incorrect because the passage cites monoculture as a cause of site quality decline in the 'Indian plains,' not specifically in Tropical Asia, Africa, and South America, which are mentioned only in the context of deforestation consequences.

• Therefore, only Statement 1 is a valid inference, making option (a) the correct answer.

Why the other options are wrong

(b) 1 and 2 only: Statement 2 is incorrect because the passage does not claim salinization is caused 'only' by human activities.
(c) 2 and 3 only: Statement 3 is incorrect because the passage attributes monoculture issues to the Indian plains, not Tropical Asia, Africa, and South America.
(d) None of the above is a correct inference: This option is incorrect because Statement 1 is a valid inference supported by the passage's mention of hydrological alterations.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2018, held on 3 June 2018. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.