Mangroves Plantation Along Odisha Coast

In News :

The Odisha government has proposed to raise mangrove and casuarinas plantation in the coastal belt. 

• The state has around 480-kilometres-long coastal belt.

Need

• Odisha is one the most cyclone-prone states in the country and it also is vulnerable to various natural disasters like flood, hailstorm, drought due to its unique geo-climatic condition. 
• The mangroves have acted as a bio-shield against the strong winds in all the cyclones that struck the state. 
  • Previously, the mangroves served as a natural barrier to cyclonic winds in Bhitarkanika National Park during Cyclone Yaas.
  • As many as 96 cyclones have hit Odisha coast in the last 130 years. 

• Therefore, it is important to build a coastal shelter belt to protect the coastal areas. 

• The Odisha coastal area is a wildlife hotspot as well as an economic zone.  

Mangroves

• A mangrove is a small tree or shrub that grows along coastlines, taking root in salty sediments, often underwater. 
• The word ‘mangrove’ may refer to the habitat as a whole or the trees and shrubs in the mangrove swamp. 
• Mangroves are flowering trees, belonging to the families Rhizophoraceae, Acanthaceae, Lythraceae, Combretaceae, and Arecaceae.
• The upper trunk, including the branches and leaves, of a mangrove tree, lives completely above the waterline, while the lower trunk and the large root system are partly covered by seawater. 
• Many species have roots diverging from stems and branches and penetrating the soil some distance away from the main stem (like banyan trees).
• Features:
  • Saline Environment: A speciality of mangroves is that they can survive under extreme hostile environments such as high salt and low oxygen conditions.
    • Mangrove trees contain a complex salt filtration system and complex root system to cope with saltwater immersion and wave action. 
    • The roots filter out 90% of the salt they come into contact with within the saline and brackish water they call home. Some species of mangrove excrete salt through glands in their leaves.
  •  Low oxygen: Underground tissue of any plant needs oxygen for respiration. But in a mangrove environment, the oxygen in soil is limited or nil.
    •  Hence the mangrove root system absorbs oxygen from the atmosphere.
    • Mangroves have special roots for this purpose called breathing roots or pneumatophores.
      •  These roots have numerous pores through which oxygen enters the underground tissues.
  • Store Freshwater: Mangroves, like desert plants, store fresh water in thick succulent leaves. A waxy coating on the leaves seals in the water and minimises evaporation.
  • Mangroves are viviparous: Their seeds germinate while still attached to the parent tree. Once germinated, the seedling grows into a propagule. 
    • The mature propagule then drops into the water and gets transported to a different spot, eventually taking root in a solid ground.

Distribution of Mangroves 

• Mangroves can be found in over 118 countries and territories in the tropical and subtropical regions of the world. 
  • Asia has the largest coverage of the world’s mangroves, followed by Africa, North and Central America, Oceania and South America. Approximately 75% of the world’s mangrove forests are found in just 15 countries.
  • In India:
    • The deltas of the Ganges, Mahanadi, Krishna, Godavari, and the Cauvery rivers contain mangrove forests. 
    • The backwaters in Kerala have a high density of mangrove forest.
    • The Sundarbans in West Bengal is the largest mangrove region in the world and a UNESCO World Heritage Site. It spans from the Hooghly River in West Bengal to the Baleswar River in Bangladesh.
    • The Bhitarkanika mangrove system in Odisha is India’s second-largest mangrove forest. 
    • Pichavaram in Tamil Nadu has a vast expanse of water covered with mangrove forests. It is home to many aquatic bird species.

Importance of Mangroves

• Mangrove forests act as natural barriers against storm surge, coastal flooding and sea-level rise. 
  • Their intricate root system stabilises the coastline, reducing erosion from storm surges. Together with the tree trunks, they work like speed-breakers to slow down the tides.
• Mangrove thickets maintain water quality by filtering pollutants and trapping sediments originating from land.
• They provide habitat for a diverse array of terrestrial organisms. 
  • Their branches provide homes for lizards, snakes and nesting birds. Many species of coastal and offshore fish and shellfish rely exclusively on mangroves as their breeding, spawning, and hatching grounds.
• Mangroves also have a big impact on climate. Mangroves are powerhouses when it comes to carbon storage. 
  • Studies indicate that mangroves can sequester (lock away) greater amounts of carbon than other trees in the peat soil beneath. They store this carbon for thousands of years.
• Many people living in and around mangroves depend on them for their livelihood.
  •  The trees are a source of wood for construction and fuel. The ecosystem provides local fishermen with a rich supply of fish, crabs and shellfish. The ecosystem also supports tourism.

Image Courtesy: UNEP

Major Threats

• Scientists estimate that at least one-third of all mangrove forests have been lost during the last few decades.
  • Coastal development, including the construction of shrimp farms, hotels, and other structures, is the primary threat to mangroves.
  • Mangrove forests are cleared to make room for agricultural land and human settlements.
  • Mangrove trees are used for firewood, construction wood, charcoal production, and animal fodder. In some parts of the world, there has been overharvesting which is no longer sustainable.
  •  Overfishing, pollution, and rising sea levels are the other threats to mangrove forests and their ecosystem.

Conclusion

• The mangroves have a crucial role in sustaining and preserving the coastal ecosystem. The threats posed by human activities can disrupt the natural balance and cause their depletion. 
• Hence, efforts need to be taken to compensate for the plants that are damaged due to various natural and anthropogenic activities with proper plantation drives.

Source:DTH