Included here are the lowlands of the lower courses of the Ganges and Brahmaputra, the lowlands of Orissa north of the Mahanadi River and the tropical parts of Assam, Manipur, Nagaland and Tripura.

Bengalian Sundarbans Tidal Forest

The tidal forests of Sundarbans occupy some 7800 km2 and represent the most extensive stretch of mangrove forest in the world. They are subject to massive amounts of freshwater flushing from upland snowmelt and the heavy monsoonal rainfall and so salinity remains relatively low. In fact, one of the principal trees Heritiera fomes has little adaptive tolerance to high salinity and is unknown from any other mangrove swamp.  Nevertheless, virtually all plants of this ecosystem are distributed according to variations in salinity caused by tidal inundation. In the Sundarbans of Bangladesh the main arboreal species include Dalbergia spinosa, Heritiera fomes, Phoenix paludisa and Sonnerata apelata, while the nipa palm Nypa fruticans is abundant in the most frequently inundated, low salinity areas adjacent to riverbanks. In the driest areas typical mangrove species become less conspicuous while species like Casuarina equisetifolia, Ipomoea pescapre, Pongamia pinnata, Tamarix dioica and Vitex trifolia often dominate. The mangroves Rhizophora apiculata and R. mucronata occur in southern areas but are mostly shrub-like and in fact, species of Rhizophora are generally of minor importance compared with most of the other world’s mangrove swamps. On the other hand, the Sundarbans support a huge diversity of plants but very few are of economic importance. Some other the typical herbacous species include Cyperus tegetiformis, Fimbristylis ferruginea, Mariscus albescens, Bulbophyllum xylocarpi, Dendrobium rhizophoretii, Pandanus fascicularis, Andropogon squarrosus, Oryza coarctata, Zoysia pungens, Typha elephantina, Finlaysonia maritima, Hoya parasitica, Sarcolobus carinatus, Derris heterophylla, Dendropthoe pentandra, Entata pursaetha, Stenochlaena palustre, Polypodium irioides, and Acrostichum aureum.


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