Biodiversity of Assam - Flora & Fauna : Assam Geography Study Materials & Notes
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Biodiversity of Assam - Flora & Fauna : Assam Geography
Biodiversity refers to the variety of life forms at all levels of organization, from gene through species to higher taxonomic forms and also includes the variety of ecosystems and habitats as well the processes occurring therein. Biodiversity is fundamental to the fulfillment of human needs – a biodiversity rich region offers wide options and
opportunities for sustaining human welfare including adoption to changes.
India is one of the 17 Mega biodiverse countries in the world and accounts for 7-8 % of the recorded species. The State of Assam is a constituent unit of the Eastern Himalayan Biodiversity Region; one of the two biodiversity “Hot Spots” in the country. The climatic condition and wide variety in physical features witnessed in Assam have resulted in a diversity of ecological habitats such as forests, grasslands, wetlands, which harbour and sustain wide ranging floral and faunal species.
The Orchids of Assam
In Assam as many as 293 species of Orchids are reported which represent 44.39% of North East species and 24.42% of species occurring in India. Orchids as a group of flowering plants exhibit wide range of habits and have specific macro climatic requirements for their growth, development and regeneration. Assam orchids show all the habits and growth forms found in Orchidaceous taxa. Mostly they are epiphytes. Goodyera procera and Spiranthis sinesis are adapted to aquatic habitant whereas Vanilla pilifera and Galeola altissima are climbers.
Orchids grow to their magnificent best in the Evergreen and Semi- Evergreen forest and to some extent in Moist Deciduous forests. Species belonging to genera Acanthephippium, Anoectochilus, Apostasia, Agrostophyllum, Coelogyne, Cymbidium, Dendrobium, Eria, Oberonia,, Calanthe, Eulophia, Geodorum, Habenaria, Malaxis, Nephelaphyllum, Vanilla, Zeuxine, Didymoplexis, Galeola, Bulbophyllum, Camarotis are the commonly found orchids.
Bamboos in Assam
Bamboos have gained considerable importance in the socio-economic life of people in Assam for the variety of uses they cater to. Altogether 38 naturally growing species of bamboo are recorded in Assam of which Bamboosa masrtersei is restricted in distribution to Dibrugarh district. Bamboosa cacharensis, Dinochlora compactiflora, D.india are restricted to Barak Valley. Chimnobabusa griffithiana and Oxetenanthera parviflora are restricted in distribution to N.C.Hills. Bambusa rangaensis grows wild in the Ranga R.F. of Lakhimpur district. Bamboosua vulgaris is the introduced species cultivated throughout Assam as ornamental plant.
Bambusa jaintiana and Melocanna arundiana are the species reported only from Assam. There are no exclusive bamboo forest in the plains of Assam, bamboo grooves are found mostly along the edge of Reserve Forests. But pure bamboo forests occur in N.C Hills and Karbi Anglong districts predominated with Melocanna baccifera and Chimnobambusa griffithiana.
Bamboo is cultivated widely in Assam and every household grows bamboo in its bari land. Commonly cultivated species are Bambusa balcooa (Bhaluka bamboo), Bambusa tulda (Jati bamboo), Malocanna bacciferra (Muli bamboo), Dendrocalamus hamiltonii (Koko bamboo) and Dendrocalamus giganteus (Mokalm bamboo).
Cane Diversity
14 species of cane grow in cane brakes in forests of Assam. Calamus flagellum, Calamus floribunadus, Calamus latifolius are found widely distributed throughout Assam. Plectomia assamica and Plectomia bractealis are endemic species.
Medicinal Plant diversity
Assam is home to a good number of plants having medicinal uses in Aurvedic, Unani, Homeopathic and even modern medical practices. Quite a few of them are used by traditional village practitioners called Bej and people respond favourably to these traditional practitioners particularly in rural areas. Altogether, 952 plants species have been identified which have uses in medical practices in some form or other. Asparagus racemosa (Satmul), Curcuma aromatica (Ban-haldi), Emblica officinalis (bel), Terminalia species (Hilikha, Bahera), Eugenia jambolana(Loha-jam),Garcina species (Thekera), Holarrhina antidysentrica (Dudhkuri), Hydnocarpus kurzii (Chalmugra), Litsea cubeba (Mejankuri), Ocimum species.(Tulsi), Phlogocanthus thyrsiflorus (Titaphul), Piper longum (pipoli), Saraca indica (Asoka), Wedelia calandulacea (Mahabhringraj), Zinziber officinalis (Ada) are some of the most commonly used plants in treatment of various aliments. But the list is not exhaustive.
Endemic Flora
Endemic flora is plants which occur in a restricted area. Altogether 165 species of plants have been recorded which are restricted in distribution to certain pockets in Assam, though some of them show extended destruction in the N.E. Region and elsewhere in India. However about 100 such species have distribution restricted to Assam only. These include trees e.g. Accacia gageana, Adiantum assamicum, Alseodaphne andersonii, Alseodaphane khasyana, Angiopteris assamica, Cedrela fabrifuga, Cinnamomum cacharensis, Coelogyne assamica, Combretum wallichii, Dinochloa indica, Diospyros cacharensis, Dipterocarpus mannii, Eugenia cyanophylla, bamboos e.g. Bambusa cacharensis, Bambusa mastersii, Chimnobambusa griffitheana, orchids e.g. Bulbophyllum elassonotum, Bulbophyllum vireus, Dendrobium assamicum etc.
Rare and Endangered Species
From all available account following categories of threatened plants recognized by the IUCN have been reported from Assam.
Extinct: Bambusa mastersii, Cleisostoma arietinum, Cyperus corymbosus, Dendrobium assamicum, Dendrobium aurantiacum, Hetaeria anomala, Liparis stachyurus and Sapria himalayana.
Paphiopedilum specerianum is reported to be extinct in wild. Besides the above; 284 species of plants are observed to be critically endangered, 149 species as endangered, 58 species as vulnerable, 13 species as near threatened.
The Rich Faunal Diversity
Assam is part of the transitional zone between the Indian, Indo- Malayan and Indo- Chinese Biographical regions. Favourable climate, topographic and edaphic factors support luxuriant growth of diverse plant communities and create varied habitats. The Wet Evergreen, Semi-Evergreen, Moist Deciduous, Wet Savannah and riparian forest as
well as extensive network of river systems and swamps , marshes and wetlands provide ideal conditions and suitable habitat for sustenance of wide variety of fauna be it mammals, primates, reptiles, amphibians, fishes, mollusks , birds, butterflies, moths etc. With existence of one of the most diverse faunal population; Assam provides the gateway for spread of both oriental and Palaearctic fauna to other parts of the country.
Mammals
Assam forms the western most boundary for the Indo-Chinese species including primates and the easternmost limit of several peninsular mammalian fauna. The distributional extent of several Indian species including clawless otter, the spotted deer, the swamp deer, the stone marlin, the hispid hare, the great Indian one horned rhinoceros, the pigmy hog etc. have terminated in Assam plains. The distributional range of several Indo-Chinese fauna gets its sustenance from this region. Mention can be made of its sustenance from this region. Mention can be made of such species like clouded leopard, the marbled cat, the golden cat, the spotted linsang, the large Indian civet, the binturong, the crab eating mongoose, the ferret badger, the hog badger, the hoary bamboo rat, the bay bamboo rat
etc .Assam is home to all the primate species found in the North Eastern region. Besides, many of the relict mammalian fauna of peninsular India particularly those occurring in the Western Ghats have close relationship with Assam and N.E region and therefore undoubtedly Assam holds a key place in the evolutionary process of divergence of mammalian fauna in India.
Assam’s mammalian diversity is represented by 193 species which are widely distributed in this region. But of late some of the species like one horned rhinoceros, water buffalo, pigmy hog, swamp deer, golden langur, and hoolock gibbon have their distribution limited to isolated pockets and protected areas.
Primates
Out of 15 Indian primate species 9 are found in Assam. Hoolock gibbon is the only ape found in India. The other primate species are golden langur, capped monkey, rhesus macaque, pigtail macaque, stump tailed macaque, Assamese macaque, and slow Lorries. Golden langur or “Sonali Bandar” as it is known locally is confined between Sankosh river in the west; Manas in the east; Brhmaputra in the south and mountains in Bhutan in the north. Pigtail macaque and stumped tailed macaque locally known as Gahorinejia Bandar and “ Senduiria Bandar” respectively are distributed in the Eastern, central and southern part of the state. Rhesus macaque, capped monkey and Assamese macaque are more or less distributed through the State. Assamese macaque and Rhesus monkeys are also found in villages and in urban areas.
Most of the primates are predominately arborcal in nature but Rhesus monkey, Assamese macaque and stump tailed macaque are partly terrestrial also.
Slow Lorries is the only prosimian found in Assam and the N.E. region. Locally known as “Lajuki Bandar” they are solitary animals and obligate canopy dwellers. Because of the habitant loss and fragmentation the primates are facing serious threat to their survival.
Birds
Assam is one of the “endemic bird areas” in the world. With 950 bird species the State is home to 53.5% of the bird species found in the Indian Sub- Continent, 17 species of birds are endemic to Assam and include Manipur Bush Quail, Marsh Babbler, Snowy throated Babbler, Tawny breasted Wren Babbler, Blyth’s Tragopan, Beautiful Sibia, Grey sibia, Black breasted Parrotbill, Chestrunt breasted partridge, Rusty breasted shortwig etc.
45 species of birds from Assam find mention in the Indian Red Data Book and include white winged wood duck (Assam’s State Bird), Blyth’s Tragopan, Greater Adjutant, lesser Adjutant, Leser whitefronted Goose, Merbled Teal, Beer’s Pochard, Palla’s Sea Eagle, Greater spotted Eagle, Green Peafowl, White rumped vulture, longbilled vulture etc.
Reptiles
Assam’s varied physiography and habitat conditions support a rich variety of reptilian population. Gangetic gharial, 19 species of tortoises and 77 species of snakes and lizards are found in the state.
Amphibians
Assam and other parts of the N.E. region have 70 species of Amphibions reported from the region. Gangenophis fulleri and Ichthyphis garoensis are endemic to Assam.
Fish Diversity
The Brahmaputra and Barak river system along with their tributaries and flood plain wetlands locally known as beels provide very condusive habitant for an array of fish species, Assam and other parts of N.E. region is recognized as one of the hot spots of fresh water fish biodiversity.
197 food, sports and ornamental fish species are reported from the region of which 185 are reported from Assam. The important ornamental fish species are colisa, Nemacheilus, Danio, Botia and Chaca. Commercially important fish species include, Rohu, Ktla, Pabha, Pabda Chital, Magur, Singi, Sol, etc. Over exploitation is posing serious threats to fish diversity and 25 species are identified as threatened.
Butterfly
These are amongst most beautiful creatures on earth. Around 1500 species of butterflies are reported from India of which nearly half are reported from Assam and N.E. India. The Swallowtail butterflies occupy an important place and the IUCN has identified the entire N.E. Region as Swallowtail rich zone under “Swallowtail Conservation Action Plan”. Butterflies play an important role in pollination of plants and besides being important aesthetically they play important role in biodiversity conservation.
Forest Wealth
From the point of view of area and products, forest wealth occupies a very significant place for the economic development of the State. Every year the forest Department of the Government of Assam earns crores of rupees as State revenues. It may be mentioned here that except for some wood land grants under the tea estate, most of the forests of Assam are owned by the State. The acquisition of erstwhile Zamindary forests has brought a substantial part of forest areas to the state control.
Forest areas under the control of the State fall mainly under the broad categories, namely
(i) Reserved Forests,
(ii) Unclassed State Forests and
(iii) Forests under the control of the Autonomous Bodies in the Hills.
The Reserved Forests are by far the most important which can be considered for scientific management. These forests, besides providing employment and earning handsome revenue to the State, also help for the growth and development of large number of local saw mills, plywood factories, match factory and various other forest-based industries in the State and outside. Moreover, most of the forest areas are also rich in respect of their wild life. The out turn of the forest wealth includes timber for various constructional purposes, round wood for bridges and for use by the State Electricity Board, for use in the plywood factories,and lastly as firewood for domestic purposes.
Forest and Tree Cover
The estimated tree cover in the state is 1,564 sq km which is 1.99% of geographical area of the state. Forest cover in the state is 27,673 sq km that is 35.28% of the geographical area of the state. Thus the Forest and tree cover in the state is 29,237 sq km which is 37.27% of the geographical area.
Biodiversity Particulars – Estimated Number of Species
Flowering Plants – 3017
Wild Orchids – 193+
Bamboo – 42
Canes – 14
Mammals – 164+
Primates – 10
Bird – 800+ (280 migratory)
Ambhibians – 60+
Butterflies – 1500 approx.
Reptiles – 116 approx.
Pride of Assam Forests
Assam State Animal – One horned Rhino
Assam State Plant – White-Winged Wood Duck
Assam State Tree – Hollong Tree
Assam State Flower – Kapou Phool (Orchid).
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