Mangroves
Mangroves are plants of different types such as a tree, shrub, palm and even fern of diverse evolutionary origins, evolved with convergent adaptation to thrive in harsh intertidal environment between land and sea which is open to vagaries of both sea and land such as flood, storm, high salinity, draughts, shifting of sediments, tidal inundation and exposure. The community of mangroves is an ecological assemblage of plants rather than taxonomical or morphological grouping.
In other words, representative plants of different families have evolved the means to survive intertidal environment between land and sea and become a mangrove in the course of evolution. There are many plant families that are adopted to the intertidal environment, but only a few families are exclusive mangroves. This suggests that mangroves are not primitive, and they evolved in due course of time.
Extent and Distribution
Mangroves are restricted to 30° North and 30° South latitude. However, the most northernly mangroves are located at 31°22.5' N near the town of Kiire of Japan in the northern hemisphere and most southerly mangroves are located at 38°45' S of Australia, where the mangroves exist below freezing point.
Generally, mangroves dominate on the coast and the river banks up to which the tidal water ingress during high tide in the tropical and sub-tropical regions. The distribution pattern of mangroves is the result of latitudinal limit; particularly sea surface temperature, air temperature and inland rainfall.
Global Mangrove Cover
The total mangrove cover area of world is 152,361 sq. km (Giri et al., 2011). The mangrove cover has greatly decreased since the last century. Globally, it comprises less than 1% of tropical forest cover and 0.4% of total forest cover of world (FAO, 2006).Mostly mangroves are dominantly tropical forests and are found in the tropical region of South-east Asia, south Asia, North and Central America, South America, West and Central Africa and south Asia.Among them maximum area of mangroves is found in South-East Asia region over an area of 52,049 sq. km followed by South America region with 23,882 sq. km, North and Central America region with 22,402 sq. km and West and Central Africa region with 20,040 sq. km. The least mangrove cover is found in the Middle East with 624 sq. km.
In political perspective mangroves are found in 123 countries worldwide among which 12 countries comprise nearly two thirds of mangrove cover. Indonesia has maximum mangrove cover comprising 20.9 % of world total mangrove cover. Next to Indonesia, Brazil, Australia, Mexico, Nigeria, Malaysia, Myanmar, Bangladesh, Cuba, India, Papua New Guinea and Columbia have mangrove cover in descending order area wise
Figure 1.2: Global Mangrove Distribution by Region
TABLE 1.1: Twelve countries with the largest mangrove area
| Country | Mangrove Area (sq.km) | Proportion of Global Total |
|---|---|---|
| Indonesia | 0 | 20.9% |
| Brazil | 0 | 8.6% |
| Australia | 0 | 6.5% |
| Mexico | 0 | 5.0% |
| Nigeria | 0 | 4.8% |
| Malaysia | 0 | 4.7% |
| Myanmar | 0 | 3.3% |
| Bangladesh | 0 | 3.2% |
| Cuba | 0 | 3.2% |
| India | 0 | 2.8% |
| Papua New Guinea | 0 | 2.8% |
| Colombia | 0 | 2.7% |
| Rest of countries | 0 | 22.5% |
