Littoral beach forests include about 400 species of trees, shrubs, herbs and climbers forming impenetrable thickets along the shore. The broad natural zonation is often disturbed by human activities in populated islands. The out-post species of the littoral forest include Ipomoea pes-caprae, Vigna marina, Scaevola sericea, Vitex trifolia etc. The inner littoral species are Hernandia peltata, the giant Manilkara littoralis, the massive Calpohyllum inophyllum etc. Among the species thriving in the coastal zone about lpO species have economic value and are subjected to human pressure. Important coastal plant species, about 76 in number and their economic utility are given. Of these coastal plant species 7 are endemic while 60 species are common. There are 14 rare species and 2 species namely Neisosperma oppositifolium and Xylocarpus moluccensis are threatened with exploitation.
Tidal swamp forests in the islands are constituted by about 30 species. Large scale exploitation of germplasm i.e. seeds, Suits and associated macrofungi may endanger the natural regeneration capacity of these species.
The most important component of coastal vegetation is the occurrence of fringing mangroves in several islands. Occupying about 11.6% of the total geographical area, the mangroves of Andaman and Nicobar Islands are the third largest in India after Sunderbans and Gujarat on the mainland. There are about 50 species of mangroves, semi-mangroves and associate mangroves occuring in these mangrove forests. There has been a decrease in mangrove forests, which were cleared for human settlement, and for plantation of red oil palm in Little Andaman, besides extraction of timber and fuel wood. Between the years 1981-82 and 1984-85 a total of 73668m3 of wood was extracted from mangroves for charcoal. This and other exploitative activities have reduced the mangrove cover from 1826 sq. km. in 1957 to 966.sq. km. in 1998. The latest satellite figure is, however, to be verified by ground data. But sonic of the management practices such as cessation of wood extraction from mangroves, the process of regeneration in some areas and declaration of Wild Life Sanctuaries. National Parks have prevented mangroves from further degradation. The mangroves in the islands arc still in a better condition than those on the mainland. The National Committee 011 Mangroves and Coral Reefs had recommended a Management Plan for the mangroves of North Andaman islands.
The marine algae and sea grasses were dealt in other reports of the project and hence those aspects which were not covered in them are dealt in this report. For the first time, through the efforts of this project, the species diversity of seaweeds and their utility have been projected. About 65.3% of the estimated algal diversity has been enumerated up to species level. But there are still gaps in our knowledge on their spatial distribution. Coralline algae are the least known group. Altogether 16 species of crustose corallines and 8 species of articulated corallines are known to occur in the islands. However, more studies are needed with reference to this group and capacity-building in taxonomy is essential. Mariculturc potential of the islands was stressed by several committees but so far no attempt was made to start the culture of seaweeds. A pilot phase programme for the culture of seaweeds for sustainable coastal livelihood may form an important component of the full project.