NATURAL HERITAGE

Mangroves

Mangroves are various types of trees up to medium height and shrubs that grow in saline coastal habitats in the tropics and subtropics. Mangroves in India account for about 5 percent of the world's mangrove vegetation and are spread over an area of about 4,500 km2 along the coastal States/UTs of the country. Kerala was once blessed with this amazing ecosystems about 700 sq.km mangroves were present till 1957 but it is now in a declined state. It has reduced to less than 17.0 sq. km. More than 80% of the mangroves are under the custody of private owners; therefore, they are under serious threat of destruction. There are 59 species of mangroves are represented in India out of that 14 of them are represented in Kerala (Source: Malayala Manorama Daily, 26th Friday, 2006).
There are around 80 different types of mangroves. All of these trees grow in areas with low-oxygen soil, where slow-moving water allows fine sediment to build up. Mangrove forests only grow in tropical and subtropical latitudes near the equator because they cannot tolerate freezing temperatures.
Many mangrove forests can be recognized by the dense interweaving of supporting roots that make the trees appear to be standing on stilts above the water. The intertwining of the roots allows the trees to handle the daily high and low of the tides, which means that most mangroves are flooded at least twice a day. The roots also slow down the tidal movement, causing sediments to settle out of the water and collect on the muddy bottom.
Mangrove forests stabilize the coastline, reducing erosion from storm surges, currents, waves, and tides. The intricate root system of mangroves also makes these forests attractive to fish and other organisms seeking food and shelter from predators. In Kerala, only Kannur district has good natural patches. There were approximately 755 hectare of mangrove forest in Kannur However, it has now become reduced to 17 km. (FSI, 2003).

Distribution of mangroves in Kerala. (Source: Kerala State Biodiversity Board)

The District-wise distribution of mangrove vegetation in Kerala