BIODIVERSITY OF WETLANDS IN TERAI REGION OF NEPAL:
A LITRATURE REVIEW
By: Gandhiv Kafle
Of the 861 bird species (BCN, 2004) found in Nepal, 193(22.5%) are known to be dependent on wetlands. Of these wetland dependent species, about 187 are known to be dependent on the wetlands of the Terai. 180 species of water birds are reported from Koshi Tappu and the Koshi barrage(IUCN Nepal, 1996).The IUCN Red List of 2003 lists 12 globally threatened species that are wetland dependent, including the Critically Endangered Pink-headed Duck(Rhodonessa caryophyllacea), Endangered Greater Adjutant(Leptoptilos dubius) and Lesser Florican(Sypheotides indica) and Vulnerable Baikal Teal(Anas Formosa), Swamp Francolin(Francolinus gularis), Baer’s Pochard(Aythya baeri), Grey Pelican(Pelecanus philippensis), Sarus Crane(Grus antigone), Indian Skimmer(Rynchops albicollis), Black-necked Crane(Grus nigricollis), Lesser Adjutant(Leptoptilos javanicus) and Band-tailed Fish Eagle (Haliaeetus leucoryphus)(IUCN Nepal, 2004).
The oriental darter that breeds in just 13 countries is a resident breeder in Chitwan, Koshi Tappu and at Ghodaghodi Tal. The spot-billed pelican, a globally threatened bird, is found on a seasonal basis at the Koshi barrage, while the wetlands in Rupandehi and Kapilbastu provide habitat for the Sarus crane (HMGN/MFSC, 2002).
The key globally threatened mammals in Nepal that are wetland dependent include the critically endangered pygmy hog(sus salvanius), endangered gangetic river dolphin(Platanista gangetica), wild water buffalo(Bubals bubals), greater one-horned rhinoceros(Rhinoceros unicornis), elephant(Elephas maximus) and tiger(Panthera tigris), Vulnerable Indian smooth-coated otter(Lutrogale perspicillata) and common otter(Lutra lutra), Fishing Cat(Prionailurus viverrinus) and Barasingha(Cervus duvaucelii)(IUCN Nepal, 2004).
Thapa (1997) inventoried 5052 species of insects in Nepal. The vulnerable relict Himalayan dragonfly (Epiophlebia laidlawi) is the only globally threatened wetland dependant species known to occur in Nepal.
A total of 185 species of fish are found in wetlands of Nepal, out of which 8 are endemic. Shah (1995) has recorded 100 species of reptiles (24 lizards, 14 turtles, 2 crocodiles and 60 snakes) and 43 species of amphibians (one salamander, four toads and 38 frogs) in Nepal. The IUCN Red List includes nine reptilian species including the critically endangered Bengal Roof Turtle (Kachuga kachuga), endangered three striped roof turtle (Kachuga dhongoka), Elongated Tortoise (Indotestuda elongate) and Gharial (Gavialis gangeticus), Vulnerable Broad-snouted crocodile (Crocodylus palustris), Crowned River Turtle (Hardella thurjii), Indian Eyed Turtle (Morenia petersi), Black pond turtle (Geoclemys hamiltonii) and Three-keeled Land Tortoise (Melanochelys tricarinata). Of the 20 endemic vertebrate animals found in Nepal, 17- including 8 fish and 9 heterofauna species- are wetland dependant (IUCN Nepal, 2004).
Terai wetlands host considerable floral diversity. At least 318 wetland dependent plant species have been recorded here. Twelve of these are floating species, 16 species are submergent, and 290 species are amphibious/emergent. Of the total amphibious species, 254 species are found exclusively in aquatic habitats, 11 species in riverine and ravine forest habitats, 21 species in savannah grasslands, and 42 species on anthropogenic lands. However it must be noted that a large number of species occur in more than one habitat.
IUCN Nepal (2004) classifies the vegetation (hydrophytes) of oxbow lakes of Terai into 3 categories. They are floating hydrophytes, submerged hydrophytes and emergent hydrophytes. There are over 12 species of floating hydrophytes, which provide a nesting habitat for birds such as the Pheasant-tailed Jacana, Bronze-winged jacana, and Purple Moorhen (Sankhala, 1990). 16 submerged hydrophytes occur in the oxbow lakes of the Terai which provide food for fish and a habitat for large numbers of invertebrates(especially crustaceans) and some birds such as Pintails(Anas acuta).
A total of 290 species of emergent hydrophytes have been reported from the Terai, which provide nesting habitat for bitterns, purple heron, finches; roosts for Rosy Pastor, wagtails, and purple Moorhen and vantage perch for Ringed-tailed Fishing Eagle, Purple Moorhen and kingfishers (Sankhala, 1990).
3. Aquatic invasive species
A recent assessment of aquatic invasive species by IUCN Nepal shows that the most common invasive species in the wetlands of eastern Nepal are Ipomoea carnea ssp. Fistulosa, Alternanthera philoxeroides (Mart.) Griseb and Eichhornia crassipes. They occur extensively in the Koshi Tappu Wildlife Reserve and its surroundings. Mikania micrantha is now seen covering the forest floor and many of the Dalbergia sissoo trees inside the Koshi Tappu Wildlife Reserve (IUCN Nepal, 2004).
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Shree Laxmi Secondary School
Institute of Forestry
Place of Birth:
Gaikhur-1, Gorkha, Nepal