Detailed Explanation:

Answer: Option 4 — Statement I is incorrect but Statement II is correct

This question tests understanding of tropical rainforest soil characteristics and nutrient cycling. Statement I incorrectly claims that tropical rainforest soils are nutrient-rich, when in reality they are nutrient-poor due to rapid leaching by heavy rainfall. Statement II correctly explains that high temperature and moisture accelerate decomposition of organic matter.

❌ Statement I – Incorrect: Tropical rainforest soils are actually nutrient-poor (not rich) because heavy rainfall causes rapid leaching, washing away nutrients before they can accumulate in the soil.

✅ Statement II – Correct: High temperature and moisture in tropical rainforests create ideal conditions for rapid decomposition of dead organic matter by bacteria and fungi, quickly recycling nutrients back into the ecosystem.

📝 Short Notes: Tropical Rainforest Soil and Nutrient Cycling

• Soil Characteristics: Tropical rainforest soils are typically nutrient-poor, acidic, and have low fertility despite supporting dense vegetation.
• Rapid Leaching: Heavy rainfall (2000-10000 mm annually) washes away soluble nutrients from the topsoil, preventing their accumulation.
• Nutrient Paradox: Despite poor soil, rainforests support luxuriant growth because nutrients are locked in the biomass (living plants and organisms) rather than in the soil.
• Rapid Decomposition: High temperature (25-30°C) and humidity (>80%) facilitate quick breakdown of organic matter by decomposers within weeks.
• Closed Nutrient Cycle: Nutrients released from decomposition are immediately absorbed by plant roots and mycorrhizal fungi, preventing loss through leaching.
• Shallow Root Systems: Most rainforest trees have shallow, spreading roots to quickly capture nutrients before they are leached away.
• Agricultural Implications: When rainforests are cleared for agriculture, the thin nutrient layer is quickly depleted, making the land infertile within 2-3 years.