Mangroves
Mangroves – Complete GK Notes for Railway Exams
1. Introduction & Definition
- Mangroves are salt-tolerant (halophytic) evergreen forests found in inter-tidal estuarine & coastal zones.
- UNESCO tag-line: “Coastal forests that breathe through their roots.”
- Ecotone between land & sea; among the most productive ecosystems on Earth (Net Primary Productivity ≈ 10 t/ha/yr).
| Term | Meaning |
|---|---|
| Halophytes | Plants tolerating saline water |
| Pneumatophores | Aerial roots (e.g., Avicennia) for gas exchange |
| Vivipary | Seeds germinate while still on mother tree (e.g., Rhizophora) |
2. Global & Indian Coverage (Latest Estimates)
| Region | Area (km²) | % of World |
|---|---|---|
| World (2022, FAO) | 1,47,500 | 100 |
| Asia | 1,08,000 | 73 |
| India (2021, ISFR) | 4,992 | 3.4 |
| Sundarbans (IN part) | 2,633 | 52.7 of India |
- India ranks 8th among mangrove nations & 1st in South Asia.
- Forest Survey of India biennial report – ISFR 2021 – shows 23.37% increase since 2011.
3. Distribution in India – State-wise Snapshot
| Rank | State/UT | Area (km²) | % of India’s total |
|---|---|---|---|
| 1 | West Bengal | 2,113 | 42.3 |
| 2 | Gujarat | 1,177 | 23.6 |
| 3 | A&N Islands | 616 | 12.3 |
| 4 | Andhra Pradesh | 404 | 8.1 |
| 5 | Maharashtra | 320 | 6.4 |
| 6 | Odisha | 259 | 5.2 |
| 7 | Tamil Nadu | 49 | 1.0 |
| 8 | Goa | 27 | 0.5 |
| 9 | Kerala | 9 | 0.2 |
| 10 | Karnataka | 18 | 0.4 |
4. Important Mangrove Species
| Scientific Name | Common Name | Key Feature |
|---|---|---|
| Rhizophora mucronata | Red mangrove | Stilt-roots |
| Avicennia marina | Grey mangrove | Pneumatophores |
| Sonneratia apetala | Mangrove apple | Fast growing |
| Bruguiera gymnorhiza | Large-leafed orange mangrove | Knee-roots |
| Excoecaria agallocha | Blinding tree | Toxic latex |
5. Significance & Services
| Benefit | Brief |
|---|---|
| Carbon sink | SOC 1,024 t/ha – 4× tropical forests; Blue-Carbon |
| Storm buffer | Reduce cyclone energy by 70%; save ₹15,000 cr/yr in India (WWF) |
| Biodiversity | Nursery for 1,336 fish spp., 268 bird spp. |
| Livelihood | 1.5 cr coastal Indians depend on honey, fishery, fuel |
6. Threats & Conservation
| Threats | Facts |
|---|---|
| Aquaculture | 38% global loss 1980-2000 (FAO) |
| Sea-level rise | 4 mm/yr IMD projection |
| Cyclones | 2020 Amphan destroyed 8% Sundarbans cover |
Conservation Tools
- MISHTI (Mangrove Initiative for Shoreline Habitats & Tangible Incomes) – 2023 Union Budget – ₹2,500 cr for 540 km² new plantations.
- IUCN Red List – 16% true mangrove spp. threatened.
- Ramsar Sites with mangroves – India: 11 (Sundarans, Bhitarkanika, Pichavaram etc.)
7. Key Dates & Events
| Date | Event |
|---|---|
| 26 July | International Day for Mangrove Conservation (UNESCO 2015) |
| 1987 | Sundarbans (IN) declared UNESCO World Heritage Site |
| 2019 | ISFR introduced mangrove cover as separate class |
| 2022 | India joined UN Global Mangrove Alliance |
8. Quick-Fire One-liners (Revision Capsule)
- Largest single-block mangrove: Sundarbans (10,200 km² Indo-Bangladesh).
- State with fastest mangrove growth 2011-21: Gujarat (+37%).
- Mangrove capital of India: Bhitarkanika (Odisha) – 62 true mangrove spp.
- Sundari tree: Heritiera fomes – after which Sundarbans is named.
- First mangrove pucca tiger reserve: Sundarbans Tiger Reserve (1973).
- Pneumatophores are also called ‘breathing roots’.
- Vivipary helps seedling anchorage in shifting mud.
- Mangrove loss rate globally: 0.13%/yr (FAO 2022) – lowest ever, yet continuing.
- Godavari-Krishna delta hosts India’s 2nd largest contiguous patch.
- Miss Kerala 2023 mangrove festival held at Puzhathur (Kerala).
9. Multiple-Choice Questions (Railway Pattern)
1. India’s total mangrove cover as per ISFR 2021 is approximately
Ans: 4,992 km²
2. Which state has the highest percentage share of mangroves in India?
Ans: West Bengal
3. The aerial roots seen in Avicennia are called
Ans: Pneumatophores
4. Which mangrove species is known for toxic latex?
Ans: Excoecaria agallocha
5. International Day for Mangrove Conservation is observed on
Ans: 26 July
6. India ranks which position globally in mangrove area?
Ans: 8th
7. MISHTI scheme was announced in which Union Budget?
Ans: 2023-24
8. The term ‘vivipary’ is associated with
Ans: Seed germination while attached to parent plant
9. Largest mangrove forest in the world is
Ans: Sundarbans
10. Which state recorded the highest increase in mangrove cover between 2011-2021?
Ans: Gujarat
11. Bhitarkanika mangroves are located in
Ans: Odisha
12. What is the main function of stilt roots in Rhizophora?
Ans: Provide stability & access to oxygen
13. Which of the following is NOT a threat to mangroves?
Ans: Controlled ecotourism
14. The mangrove species Heritiera fomes is commonly known as
Ans: Sundari
15. Pichavaram mangroves are situated near the estuary of
Ans: Vellar-Coleroon (Tamil Nadu)
16. Mangroves are best described as
Ans: Salt-tolerant forest ecosystems of tidal coasts
17. How many Ramsar sites in India include mangrove habitats?
Ans: 11
Last-minute cram: Remember “4-9-26” → India’s mangroves ≈ 4,992 km², 9 coastal states have them, 26 July international day!
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