Mangrove

Also called: Mangrove forest · Topic: Natural Vegetation and Forests of India · NCERT: Class 7, Ch 1 "Geographical Diversity of India"; Class 7, Ch 2 "India and Her Neighbours"; Class 11, Ch 5 "Natural Vegetation"

Meaning

A mangrove is a salt-tolerant tree or shrub that grows on salt marshes, tidal creeks, mudflats and estuaries along tropical and subtropical coasts. It has special roots that let it breathe and stand firm in soft, airless mud. India has 4,991.68 sq km of mangrove cover, which is 0.15 per cent of its geographical area (ISFR 2023) [2].

Mangroves matter because they protect coasts from cyclones and tsunamis, store blue carbon, act as fish nurseries and support coastal livelihoods. UPSC often tests them through map sites, state rankings and schemes like MISHTI.

Explanation

Where mangroves fit in India's forest types

• Mangroves belong to the littoral and swamp forests. Littoral means "of the seashore".
• This group has two parts:
• Mangroves, which grow in deltas (where a river splits into many channels before it meets the sea) and estuaries (where a river mouth mixes fresh water with sea water).

• Swamp forests, which grow in inland marshes and wetlands.

• NCERT puts "mangrove forests and other island wetlands" as one of India's eight wetland categories, with the Andaman and Nicobar island arcs as the example.

• A tidal creek is a narrow channel that fills and empties with each tide. Mangroves line these creeks.

How mangroves survive: problem → root → result

• Problem 1: there is very little oxygen in the mud.
• Tidal mud stays soaked with water, so it holds very little air.
• Pneumatophores (breathing roots) grow upward, out of the mud.

• They take in air directly, so the roots below can breathe.

• Problem 2: the mud is soft and moves.

• The mud shifts with every tide.
• Stilt roots (prop roots) arch down from the trunk into the mud.

• They hold the tree firmly in place, the way tent ropes hold a tent.

• Problem 3: the water is salty.

• Mangroves are salt-tolerant, so they can live where sea water floods the land every day.

Conditions mangroves need

• Warm tropical or subtropical coasts.
• Sheltered, gently sloping shores with wide tidal mudflats.
• Fine silt brought by rivers, which builds the mudflats.
• A balance of salt and fresh water. River water must keep reaching the coast. When upstream dams hold back river water, this balance is upset.
• Why the east coast has more mangroves:
• East-flowing rivers (Ganga, Mahanadi, Godavari, Krishna, Kaveri) build wide, gentle deltas with large mudflats.

• The Bay of Bengal coast is more sheltered.

• Why the west coast has fewer:

• The west coast is narrow and steep and has few deltas, so mangroves grow there only in thin strips.
• Gujarat is the exception. Its gulfs are shallow and have large tidal mudflats.

What mangroves do

• They protect coasts from storm surge and tsunami. A storm surge is sea water pushed onshore by a cyclone.
• Dense roots and trunks slow the incoming waves.
• Wave energy and water speed fall.
• Less land floods, and there is less damage inland.

• In the 2004 Indian Ocean tsunami, villages behind thick mangroves, for example around Pichavaram (Tamil Nadu), suffered less damage than open coasts.

• They store blue carbon. Blue carbon is carbon stored in coastal ecosystems such as mangroves, seagrass and salt marshes.

• Mangroves take in CO₂.
• Their roots and fallen leaves get trapped in waterlogged mud.

• With little oxygen, they decay slowly, so the carbon stays locked in the soil for a long time.

• They support fisheries and livelihoods.

• Young fish, prawns and crabs grow up safely among the roots, so mangroves act as fish nurseries.

• They also shelter birds and give honey, crabs and prawns to coastal communities.

• They keep the shoreline stable. Roots trap silt, which holds the coast against erosion.

Where it occurs

India's share and spread

• NCERT figure: 4,992 sq km, about 7 per cent of the world's mangroves. NCERT says they are best developed in the Sundarbans and the Andaman and Nicobar Islands, then in the Mahanadi, Godavari and Krishna deltas.
• ISFR 2023 ranking by share of India's mangrove cover:

Rank	State or UT	Share	Area
1	West Bengal (Sundarbans)	42.45% [2]	2,119.16 sq km [2]
2	Gujarat (Gulf of Kachchh coast)	23.66% [2]	1,164.06 sq km [2]
3	Andaman and Nicobar Islands	12.39% [2]	—

• Gujarat's growth: mangrove cover rose by 253.06 sq km between 2001 and 2023, through large planting drives, Public-Private Partnership, community involvement and protection [2].

Key sites (from east to south along the coast)

• Sundarbans (West Bengal, about 21–22°N)
• It lies in the Ganga–Brahmaputra–Meghna delta on the Bay of Bengal [5].
• It is the world's largest mangrove forest, shared by India and Bangladesh [5].
• The wider area covers about 10,000 sq km of land and water, and more than half of it is in India [5].
• About 78 mangrove species have been recorded here, which makes it the richest mangrove forest in the world [5].
• It is named after the sundari tree (Heritiera fomes).
• It has the world's largest population of tigers living in mangroves. The Royal Bengal tiger here lives an almost amphibious life (partly on land, partly in water). It swims long distances and eats fish and crabs [5].
• Other threatened animals here include Ganges and Irrawaddy dolphins, estuarine crocodiles and the critically endangered river terrapin (Batagur baska) [5].

• Sundarbans National Park became a UNESCO World Heritage Site in 1987 [5]. The Bangladesh part is a separate World Heritage property [6]. The Indian Sundarbans became a Ramsar site in 2019.

• Bhitarkanika (Kendrapara district, Odisha)

• It is India's second largest mangrove ecosystem, in the Brahmani–Baitarani delta.
• It is known for saltwater (estuarine) crocodiles.

• Nearby Gahirmatha beach is a mass-nesting site for olive ridley turtles. This mass nesting is called arribada: thousands of female turtles come ashore together to lay eggs.

• Mahanadi delta (Odisha).

• Coringa (Godavari delta, near Kakinada, Andhra Pradesh).
• Krishna delta (Andhra Pradesh).
• Pichavaram (Tamil Nadu, near the Vellar–Coleroon estuary).
• Gulf of Kachchh coast (Gujarat).
• Andaman and Nicobar Islands.

MISHTI (Mangrove Initiative for Shoreline Habitats and Tangible Incomes)

• It was announced in the 2023-24 Union Budget and launched on 5 June 2023 (World Environment Day) [3].
• Target: about 540 sq km of mangroves in 9 coastal states and 4 Union Territories [3].
• Period: 2023-24 to 2027-28 [4].
• Funding: convergence, meaning money is joined from schemes that already exist: MGNREGS, CAMPA (the fund that projects pay into when they use forest land, kept for replanting) and other sources [4].
• Where it plants: along the coastline and on salt-pan land.
• Progress: in FY 2024-25, ₹17.96 crore went to Andhra Pradesh, Gujarat, Kerala, Odisha, West Bengal and Puducherry to restore 3,836 hectares of degraded mangroves [3].

Don't confuse with

• Rann of Kachchh: this is a saline wetland (a vast salty expanse), not a mangrove forest. Gujarat's mangroves grow along the Gulf of Kachchh coast.
• Swamp forests: these grow in inland freshwater marshes and wetlands. Mangroves grow on tidal, salty coasts, deltas and estuaries.
• Chilika Lake: this is a brackish-water lagoon in Odisha (a shallow coastal water body cut off from the sea by a sand bar), not a mangrove site. Odisha's major mangroves are at Bhitarkanika.
• Pneumatophores vs stilt roots: pneumatophores grow upward to breathe in oxygen-poor mud. Stilt roots arch downward to hold the tree up in soft mud.

Prelims Hooks

• ISFR 2023 mangrove cover: 4,991.68 sq km, which is 0.15% of India's area [2]. (NCERT gives 4,992 sq km, about 7% of the world's mangroves.)
• Ranking (ISFR 2023): West Bengal (42.45%) > Gujarat (23.66%) > Andaman and Nicobar (12.39%) [2].
• Sundarbans: Ganga–Brahmaputra–Meghna delta; named after the sundari tree; Royal Bengal tiger; UNESCO World Heritage Site 1987 [5]; Ramsar site 2019; shared with Bangladesh.
• Site–state pairs: Bhitarkanika → Odisha (Brahmani–Baitarani delta); Coringa → Andhra Pradesh (Godavari delta); Pichavaram → Tamil Nadu.
• Root–function pairs: pneumatophores → breathing; stilt roots → support in soft mud.
• MISHTI: launched 5 June 2023; 540 sq km; 9 states and 4 UTs [3]; 2023-24 to 2027-28; MGNREGS and CAMPA convergence [4].

Mains Points

• Uneven distribution (GS-I):
• Mangroves are concentrated on the east coast and in the islands, because large deltas build wide tidal mudflats on a sheltered Bay of Bengal coast.
• The steep, narrow west coast has only thin strips. Gujarat's shallow gulfs are the exception.

• Gujarat's gain of 253.06 sq km between 2001 and 2023 shows that planting led by communities and partnerships can reverse the loss [2].

• Bio-shield and blue carbon (GS-III):

• The 2004 tsunami and repeated Bay of Bengal cyclones show that mangroves reduce surge damage. This supports "green-grey" coastal defence, which uses mangroves together with sea walls.

• Their blue-carbon storage helps India's carbon-sink goals, and their fish nurseries support coastal food security.

• Threats and policy response (GS-III):

• Threats: prawn and shrimp ponds (for example in the Godavari and Krishna deltas), land reclamation for farms, salt pans and towns, port building, pollution, and dams that reduce fresh-water flow.
• Response: environmental impact assessment should count these losses. MISHTI's 540 sq km target through MGNREGS and CAMPA convergence is the main policy response [3] [4].
• Open questions: how many planted seedlings survive, how well salt-pan land is chosen, and how much local communities take part.

Related concepts

• Littoral and swamp forests
• Bhitarkanika mangroves
• MISHTI

Read more

• Littoral and swamp forests: wetlands and mangroves