Mangrove forest
Explanation
The vegetation in deltaic regions is primarily determined by the interplay of fresh river water and saline seawater brought in by tides. These areas support specialized littoral and swamp forests capable of surviving in brackish water and marshy soil.
Analysis of Options:
- Coniferous forest Coniferous forest: Incorrect. These forests are found in high-altitude montane regions (such as the Himalayas) where temperatures are low. They are not found in low-lying deltaic plains.
- Deciduous forest Deciduous forest: Incorrect. Tropical Deciduous forests are the most widespread forests in India, typically found in regions with distinct dry and wet seasons (monsoon climate). They are not the primary vegetation of saline deltaic swamps.
- Mangrove forest Mangrove forest: Correct. The Ganga-Brahmaputra delta is covered by Mangrove forests, also known as Tidal forests. This region is home to the Sundarbans, the largest mangrove forest in the world. The vegetation here is adapted to high salinity and tidal submersion, with the 'Sundari' tree (Heritiera fomes) being the most dominant species, providing durable hard timber.
- Thorn forest Thorn forest: Incorrect. These forests are characteristic of semi-arid and arid regions with low rainfall (less than 70 cm), such as Rajasthan, Gujarat, and parts of the leeward Deccan Plateau.
Key Takeaway:
The Ganga-Brahmaputra delta is characterized by Mangrove forests (Sundarbans), which are distinct for their halophytic (salt-tolerant) vegetation and dense root systems that stabilize the coast against tidal surges.