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Q110 (IAS/2003) Environment & Ecology › Ecology & Ecosystem Basics › Tropical rainforest ecology Answer Verified

Assertion (A) : Unlike temperate forests, the tropical rain forests, if cleared, can yield productive farm-land that can support intensive agriculture for several years even without chemical fertilizers. Reason (R) : The primary productivity of the tropical rain forest is very high when compared to that of the temperature forests.

Result
Your answer:  ·  Correct: D
Explanation

The Assertion is false while the Reason is true. Tropical rainforests have very high above‑ground productivity, but most nutrients are held in living biomass and are rapidly cycled; dead litter decomposes quickly and released nutrients are immediately absorbed by roots, leaving soils low in organic matter and humus [1]. Clearing by fire (slash‑and‑burn) temporarily increases soil fertility through ash inputs, yet this fertility typically declines within a few years (commonly 3–5 years), forcing shifting cultivation—so such cleared rainforest cannot sustainably support intensive agriculture for many years without external inputs [2]. Thus R is correct about high productivity, but it does not validate A’s claim about long‑term productive farmland.

Sources

  1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 1. Tropical Evergreen Rainforest Biome > p. 5
  2. [2] FUNDAMENTALS OF HUMAN GEOGRAPHY, CLASS XII (NCERT 2025 ed.) > Chapter 4: Primary Activities > Primitive Subsistence Agriculture > p. 27
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