Previous Year Question

The Andaman and Nicobar Islands contain all three forest categories—tropical evergreen, moist deciduous and mangrove forests.

Why do all three forest types occur in the islands?

Local variations in rainfall, distance from the sea, salinity, tidal influence, soil, elevation and drainage allow several forest types to develop within a relatively small area.

1. Evergreen forests

• The tropical, humid and high-rainfall climate of the islands favours evergreen forests.

• The islands contain giant evergreen forests, Andaman tropical evergreen forests and southern hilltop evergreen forests.

• Dipterocarpus, Calophyllum, Artocarpus and Mesua are important tree genera in these forests.

• Tall trees and a multi-layered canopy are their important characteristics.

2. Deciduous forests

• Andaman also contains moist deciduous and secondary moist deciduous forests.

• The upper storey consists of tall trees that shed leaves during a particular season, while the lower storey may contain some evergreen species.

• Species such as Pterocarpus dalbergioides, Terminalia and Tetrameles nudiflora occur in these forests.

• Semi-evergreen forests also represent a transition between evergreen and deciduous vegetation.

3. Mangrove forests

• Mangroves occupy tidal seashores, creek mouths and inland tidal channels.

• These trees are adapted to salinity, waterlogged soil and oxygen-deficient conditions.

• Rhizophora, Bruguiera, Avicennia, Ceriops and Sonneratia are important mangrove genera.

• Besides protecting coasts from waves and erosion, mangroves provide habitats and nursery grounds for fish, crustaceans and numerous birds.

Why are the other options incorrect?

• North Coastal Andhra Pradesh may contain mangroves and deciduous forests, but it does not display the characteristic combination of all three forest categories mentioned in the question.

• South-West Bengal is primarily known for the extensive mangrove forests of the Sundarbans; it does not possess the same island sequence of evergreen, deciduous and mangrove forests.

• Southern Saurashtra supports dry deciduous, thorn and some coastal mangrove vegetation, but not wet evergreen forests.

Therefore, the correct answer is the Andaman and Nicobar Islands.