Mangroves of India

 

Mangrove are the dense shrubs or forests found along tidal estuaries and deltas, salt marshes, and on muddy coasts in the tropical and sub-tropical regions. These are mostly found in Asia, Africa and South America. The largest area of mangroves are found in Indonesia, followed by Brazil, Australia, Nigeria, and Mexico. 

The areas where mangroves are found poses many challenges for the plant community like high salinity, tidal inundation twice a day, low oxygen etc. However, mangroves are equipped with varied morphological and physiological adaptations to survive these conditions. They have complex root system that extend above and below the water line with amazing filtration system to sieve out or exclude salt. This allows them to survive in saline sea water as well as in fresh water. Mangrove have additional benefits for environment like they prevent coastline erosion, protect inner areas from tsunamis, storms and high waves and also provide habitat, breeding, and feeding grounds for aquatic and other organisms. They are important carbon sinks also known as blue carbon.

As per the Indian State of Forest Report of 2019, mangrove cover in the country is 4,975 square km, which is 0.15% of the country’s total geographical area. The largest area under mangroves is in West Bengal. Indian mangroves consist of 46 species representing about 57% of the world's mangrove species (Ragavan et al, 2016)

In India, the mangroves are mostly located in the river estuaries and deltas; backwaters and islands. Therefore, the mangroves of India are broadly classified into three regions, as (Mandal and Naskar, 2008) -

1. Deltaic or Eastern Coast Mangroves,

2. Estuarine & Backwater or Western Coast Mangroves and

3. Insular mangroves or Andaman & Nicobar Islands. 

 

Deltaic or Eastern Coast Mangroves	West Bengal - Sunderbans (Ganga-Brahmaputra)
	Odisha - Bhitarkanika (combined delta of the Mahanadi, Brahmini and Baitarani)
	Andhra Pradesh - Coringa wetland (the Gautami-Godavari river), Krishna (three islands located between Gollamattapaya and Nadimeru distributaries, and the Krishna river).
	Tamil Nadu - Pichavaram and Muthupet mangrove (Cauvery)
	Puducherry mangroves
Estuarine & Backwater or Western Coast Mangroves	Gujarat - Gulf of Kachchh; Saurashtra coast or Kathiawar; Gulf of Khambhat (estuaries like the Sabarmati, the Mahi, the Narmada, and the Tapti); South Gujarat coast (small tidal creeks and few minor estuaries.
	Maharashtra – Mumbai, Thane creek and small patches in Raigarh, Ratnagiri and Sindhudurg district.
	Goa coast - Zuari and Mandovi estuary
	Kerala - Mangroves in Kannur and Kasaragod, Kozhikode (Kadalundi), Ernakulam (Pithuvypin, Mangalvanam Bird Sanctuary and Kundannur area.), Allepey.
	Daman and Diu mangroves
Insular mangroves or Andaman & Nicobar Islands.	The mangrove forests of these islands are situated along the tidal creeks, inland channels and in shores (bays).

References -

India State of Forest Report, 2019. Forest Survey of India, Ministry of Environment, Forest & Climate Change, Government of India

Mandal, R.N. and K.R. Naskar. (2008). Diversity and classification of Indian mangroves: a review. Tropical Ecology 49, 131–146.

Ragavan, P., Saxena, A., Jayaraj, R.S.C., Mohani, P.M., Ravichandran, K., Saravanan, S., and A. Vijayaraghavan (2016). A review of the mangrove floristics of India. Taiwania, 61 (3), 224‒242.

Selvam, V. (2003). Environmental classification of mangrove wetlands of India. Current Science. 84.

 

Blue carbon

 

Mangrove Forest, Andaman and Nicobar Islands, India.

 Blue carbon is the carbon stored in coastal and marine ecosystems such as mangroves, tidal marshes and coastal seagrass meadows. These systems store large amount of carbon not only in the above and below ground biomass of the plants i.e. tree trunks, stems and leaves and root systems but also in the carbon-rich organic soils. 

 

Watch this video by Conservation International, to understand What is Blue carbon ?

 

These ecosystems are valuable to coastal communities as they provide food, timber, source of livelihood and security from storms/cyclones etc. In the same way, they have many environmental benefits such as filtration of saline water, prevention of coastal erosion and biodiversity protection.

Mangroves are estimated to be worth at least US$1.6 billion each year in ecosystem services that support coastal livelihoods and human populations around the world*.

The Blue Carbon Initiative

 

Recently their role for mitigating climate change effects has also been recognized due to their ability to remove carbon dioxide (CO2) from the atmosphere. They can act as huge carbon sinks due to their capacity to store more carbon than the terrestrial forest.

Conversely, if they are degraded or damaged, not only their carbon sink capacity is lost but it releases the stored carbon causing carbon dioxide (CO2) release that can contribute to rise in greenhouse gases. 

 

Experts estimate that as much as 1.02 billion tons of carbon dioxide are being released annually from degraded coastal ecosystems, which is equivalent to 19% of emissions from tropical deforestation globally*.

The Blue Carbon Initiative

 

On site projects and policy to protect and restore “Blue Carbon” ecosystems are being developed country wise as well as globally. For more information visit the The Blue Carbon initiative Website.

References – 

IUCN. Issues brief - Blue carbon. International Union for Conservation of Nature website, https://www.iucn.org/resources/issues-briefs/blue-carbon. Accessed on 16/12/2020.

NOAA. What is Blue Carbon? National Ocean Service website, https://oceanservice.noaa.gov/facts/bluecarbon.html. 07/24/19

The Blue Carbon Initiative. Mitigating climate change through coastal ecosystem management. The Blue Carbon Initiative website. https://www.thebluecarboninitiative.org/. Accessed on 16/12/2020