NDA (I) 2018 General Ability Test · Question 110 of 150

Correct — D, Deodar. The four options are best separated by the altitude band each occupies, and only deodar covers the whole of the 1,800 to 2,600 metre stretch the question names. Deodar, Cedrus deodara, grows between about 1,500 and 3,200 metres in the western Himalaya, so the band asked about sits comfortably in the middle of its range. Chir pine tops out at about 2,000 metres and only occasionally reaches 2,300, so it is fading out where this band begins. Himalayan spruce does not start until about 2,400 metres, so it is only appearing where this band ends. Sal is not a montane conifer at all. Deodar is the one species present across the whole interval.

• (a)Saal — Sal, Shorea robusta, is the great hardwood of the tropical moist deciduous forest — the Terai, the Siwalik foothills, central India and the Chota Nagpur plateau. It belongs to the plains and the low foothills, not to a band that begins at 1,800 metres, and it is a broad-leaved tree rather than a conifer.
• (b)Chir — Chir pine, Pinus roxburghii, occupies the belt immediately below the one asked about: roughly 500 to 2,000 metres, occasionally up to 2,300. It is the pine of the lower and middle Himalayan slopes and of hill stations, and it is exhausted before the top of this band is reached.
• (c)Spruce — Himalayan spruce, Picea smithiana, grows between about 2,400 and 3,600 metres, so it belongs to the belt above this one, in company with silver fir. It appears only in the last two hundred metres of the range named and cannot be the species of the band.

Vegetation in a mountain range is arranged in horizontal belts, because temperature falls with height at roughly 6·5 °C per kilometre and precipitation and soil change with it. In the Indian Himalaya the sequence runs from tropical moist deciduous forest with sal in the foothills, through subtropical pine forest dominated by chir, to temperate conifer forest with deodar, blue pine, spruce and silver fir, and then to alpine scrub and meadow above the tree line. The same latitudinal sequence one would walk from the equator to the pole is compressed into a few thousand metres of climb.

Answer altitude items by overlap, not by memory of a single number, because published ranges differ slightly between sources. The safe method is to fix the neighbours: sal below the hills, chir on the lower slopes, deodar in the middle temperate belt, spruce and silver fir above it, and birch and juniper near the tree line. Once that ladder is in place, a band quoted anywhere between about 1,800 and 2,400 metres can only be deodar. Deodar has a second identity worth knowing — Cedrus deodara is the national tree of Pakistan, is native from eastern Afghanistan through northern Pakistan and north-central India to western Nepal and south-western Tibet, and its durable, rot-resistant timber has been the building wood of Himachal and Kashmir for centuries, which is where the Sanskrit name devadaru, the timber of the gods, comes from.

• Deodar grows between about 1,500 and 3,200 metres; chir pine between about 500 and 2,000 metres; Himalayan spruce between about 2,400 and 3,600 metres.
• Sal is a tropical moist deciduous hardwood of the foothills and plains, not a montane conifer.
• Deodar is native to eastern Afghanistan, northern Pakistan, north-central India, western Nepal and south-western Tibet.
• Alpine vegetation reaches higher in the eastern Himalaya than in the western because the east is warmer and much wetter.

• Reading sal as a hill species because it is a famous Indian timber.
• Placing spruce and fir too low; they belong above the deodar belt, not within it.
• Memorising one published altitude figure instead of the order of the belts, which is what the item actually tests.

NDA and UPSC both set this as a species-to-altitude or species-to-region match, and the winning method is always to fix the sequence of belts first.

• practice — not a real PYQ

  Which one of the following trees is characteristic of the tropical moist deciduous forests of the Himalayan foothills and central India rather than of the temperate Himalaya?

  • (a)Deodar
  • (b)Silver fir
  • (c)Sal
  • (d)Blue pine

  Answer(c) Sal — a broad-leaved hardwood of the foothills and plains, not a montane conifer.

• practice — not a real PYQ

  Alpine vegetation in the eastern Himalaya extends to a greater altitude than in the western Himalaya mainly because the eastern Himalaya

  • (a)has older rocks
  • (b)is nearer the equator and receives far heavier monsoon rainfall
  • (c)has thinner soils
  • (d)is higher in average elevation

  Answer(b) is nearer the equator and receives far heavier monsoon rainfall — warmth and moisture together push the forest limit upward.