Vegetation

Vegetation

The kankra Bruguiera gymnorhiza is one of the characteristic plants of the tiger reserve. (Source:

The entire mangrove forest extends over an area of 4,262 km², of which 2,320 km² is forest and the rest is water, and is called Sundarban owing to the dominance of the tree species Heritiera fomes, locally known as 'sundari' because of its elegance. Thisvegetation consists of elements of the  Peninsular and Polynesian , together with some Indo-Chinese,  and a few of the New World. It is not found elsewhere except in a small part of the Mahanadi and Godaveri deltas to the southwest and the Bay Islands. Prain (1903) lists 334 species found in the Sundarbans. Champion (1936) classified the Sundarbans as moist tropical seral forest, comprising beach forest and tidal forests. The latter are subdivided into four types, of which only low mangrove forest and salt-water Heritiera forests occur within Indian territory. Beach forest occurs on coastal islands comprising low sand-dunes which, together with lime formed from disintegrating shells and salt, give rise to a pronounced xerophytic habitat despite the high rainfall. Sand-dunes are partially covered with spear-grass, behind which are creepers and shrubs or trees, such as jhao Tamarix troupii, palita Erythrina variegata and kulsi Aegiceras corniculatus. Salt-water Heritiera forest (6-11 m high), a low salinity vegetation type, occurs between the Raimangal and Matla rivers, where freshwater flows from the Ichhamati River into the Raimangal River. Characteristic species include garjan Rhizophora sp., kankra Bruguiera gymnorhiza, goran Ceriops sp., and baen Avicennia officinalis. Heritiera fomes is scattered over areas of higher elevation, along with keora Sonneratia apetala, gengwa Excoecaria agallocha, dhundul Carapa obovata and the date palm or hental Phoenix paludosa. The golpata palm Nipa fruticans is relatively uncommon but occurs on wet mud-banks along the creeks. Low mangrove forest (3-6 m high) occurs between Matla and Muriganga, to the west of the national park and tiger reserve, this area being devoid of freshwater because its rivers are cut off from the ramifications of the Hooghly in the north. Soft mud, which is submerged by the tides, supports a dense forest, very similar in composition to salt-water Heritiera forest except that sundari and golpata are virtually absent. Goran and baen are the commonest trees, occupying extensive areas but only growing up to 2 m. Clusters of hental are very common. Certain forest tracts on low-lying islands were cleared some two hundred years ago and gradually claimed for 

cultivation. Various trees and other plants were introduced, including some exotics. In a more recent examination of the composition and structure of the mangrove vegetation, 69 plant species are identified. This report also includes inventories of algae, phytoplankton and fungi. 

Management Constraints

Siltation appears to be an increasing problem. For example, it is thought by local fishermen that within the next few years the Matla River will no longer be navigable up to Canning Town. There are plans to construct a fertilizer plant at Mathurapur, just 5 km from the Satpukur sluice gate at the edge of the Sundarbans. Harmful effluents (sulfur dioxide, sulphates and fluorine) would enter the waterways of the Sundarbans. Oil spills are a potential threat which cause immense damage, especially to aquatic fauna and seabirds and probably also to the forest itself into which oil could be carried by high tides. Between 1975 to 1982, an average of 45 people were annually killed by tigers. This casualty rate has fallen since the introduction of various measures, including deterrents in the form of electrified human dummies and face masks worn on the back of the head. Between 1994 and 1995, the number of victims fell to less than 12, and this has been reduced to 2-4 per year, and villagers now tend to drive tigers back into the forest rather than kill them. Reclamation in the Sundarbans ecosystemas lead to problems of salinization and  Soil acidification although the degree to which this affects the national park is not known. The other main management constraint is poaching.