Environment

Description

Assam’s Rich Bio-Diversity

Biodiversity refers to the variety of life forms at all levels of organization, from gene through species to higher taxonomic forms and...

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 Megabiodiverse 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 placing
The word “Assam” has its origin in the Sanskrit Word “Asom” meaning unparalleled or peerless. Indeed Assam is unparalleled as nature has been uniquely generous in endowing the State with such bounties that Assam is part of one of the 25 mega diverse region on planet earth.
In his book “Red River and Blue Hills” eminent scholar Hem Barua has written, “to many outsides Assam is no more than a land of mountains and malaria, earthquake and floods and the Kamakhya Temple. To others, it is a green woodland where slothful serpents, insidious tigers, wild virulent eyes and clams. Assam to most of the people is mentally a distant horizon like Bolivia or Peru – less known and more fancied”.
However, today, Assam is not only more fancied, but also known for its ecological diversity, for the range of floral and faunal species and for the conservation successes achieved. Kaziranga, Manas, Pobitora, Orang, Dibru-Saikhowa are names recognized world over and bring laurels to the people of this magnificent State.
The Bio-spectrum
The climatic conditions cause prevalence of not and highly humid weather in this part of country and coupled with heterogenic physiography make possible luxuriant growth of a number of plant communities imparting Assam a distinct identity phytogeographically, many a species are endemic to this region and it is also the center of origin for commercially important plants including Banana, Citrus, Mango, Zizyphus, and Tea. The array of floristic richness has prompted many a scholars to describe Assam as the “Biological Gateway” of North East. The eminent Plant Taxonomist and Plant Geographer Armen L. Takhtajan observed, “Cradle of flowering plants lies in between Assam and Fiji”.

Diverse Plant Communities

In the “Revised Survey of Forest Types in India”, Champion and Seth categorized as many as fifty one different forest types/ sub types for this region. But, the species diversity is so spectacular...

In the “Revised Survey of Forest Types in India”, Champion and Seth categorized as many as fifty one different forest types/ sub types for this region. But, the species diversity is so spectacular that it becomes often difficult to clearly identify separate riche to existing plant formations. However, broadly speaking the forest in Assam can be described into following types/ sub types.
•    Tropical Wet Evergreen Forests.
•    Tropical Semi Evergreen Forests.
•    Tropical Moist Deciduous Forests.
•    Sub-tropical Broadleaf Hill Forests.
•    Sub-tropical Pine Forests.
•    Littoral and Swamp Forests.
•    Grassland and Savannahs.
Tropical Wet Evergreen Forests are found in the districts of Golaghat, Jorhat, Sibsagar, Tinsukia, Dibrugarh and in a narrow stretch in Lakhimpur and Dhemaji districts along foot hills. These forests also occur in the southern part of the State at lower elevations in Borail Range, and in Loharbund, Sonai, Longai and Dholia Reserve Forests in Cachar and Karimganj Districts.
Hollong (Dipterocarpus macrocarpus), the tallest tree of Assam and also the “State Tree” is the most predominant constituent of these forests. The associated species are Borpat, Jutuli ,Sam, Dewa sam, Nahar, Teeta chap, Bhelu, Mekai etc.
Forests in Southern Assam have, however, Dipterocarpus terbinatus(Garjan) in association with Mesua ferrea (Nahar), Mesua floribunda (Bolong), Michelia glabra (Champ), Palaquium polyanthum (Kathalua) etc.
One witness luxuriant growth of epiphytes and trees with fissured bark support magnificent ornamental orchids of Assam. Lianas, vines and climbers are plentiful twining round trees in middle canopy. Almost all the tree ferns of Assam growing majestically in these forests present a treat to the eyes. The undergrowth is dense with both low shrubs and herbs occupying the space. Canes, palms and bamboos grow along edges of forests.
Tropical Semi Evergreen Forests occur mostly in Hallangapar, Abhoypur, Dilli, Dhansiri, Kholahat, Mayong, Garbhanga, Rani, Mahamaya, Guma, Haltugaon, Kachugaon, Gali, Pobha, Ranga, Kakoi, Nauduar, Batasipur, Dohalia, Singla, Longai, Bhuban Pahar, Sonai, Barak and Inner Line Reserve Forests along Northern and Southern parts of the State.
These forests have mostly medium size trees with few large trees. Shrubs, lianas, climbers, orchids and ferns grow copiously. At the fringe bamboos and canes occupy the space.
Species association and frequency of their occurrence vary from forest to forest, but the ones commonly found are Actinodaphne obovata (Petarichawa), Aesculus species (Ramanbih), Artocarpus chama(Sam), Albizia species(Siris, Sau, Koroi), Anthocephalus chinensis (Kadam), Duabanga grandiflora (Khakan), Castonopsis species (Hingori, Dhobahingori, Kanchan),Dillenia indica (Ou-tenga), Bauhinia purpurea (Kanchan), Lagerstroemia species(Jarul, Ajar,Sidha), Magnolia species(Phulsopa, Gahorisopa, Pansopa, Kharikasopa, Kathalsopa, Duleesopa),Mallotus species(Sinduri, Joral, Dudhloti, Buritokan), Michelia champaca(Teeta campa), Syzygium species(Paharijam, Mokrajam, Berjamu, Kolajamu, Bogijamu, golapjamu). Schima wallichii (Bolem,Ghugra), Terminalia species, (Hilikha, Bohera, Bhomora), Trewia nudiflora(Bhelkor), Hatipolia, Holok etc.
Moist Deciduous Forests can further be described as Sal Forests and Mixed Deciduous Forests. Sal Forests occupy considerable forest area in the Central and Lower parts of the State in the Districts of Nagaon, Morigaon, Kamrup, parts of Nalbari and Barpeta, Darrang, Dhubri, Kokrajhar and Goalpara.
In these forests, Sal grows in association with Lagerstroemia species(Jarul, Ajar), Schima Wallichii(Ghugra), Stereospermum personatum (Paruli), Adina cordifolia (Haldu), Artocarpus species (Sam), Ficus species(Bor, Dimoru, Dhupbor, Bot, Athabor, tengabor, Lotadioru, Khongaldimoru), Bischofia javanica (Uriam), Gmelina arborea (Gomari), Michelia champaca(Teeta champa), Terminalia species (Hilikha, Bhomora, Bohera). Toona ciliate (Poma) etc.
Moist Deciduous Mixed Forests occur at the foot of hills in Lakhimpur, Dhemaji, Karbi-Angong and N. C. Hills districts. Trees are mostly deciduous with Sprinkling of few evergreen and semi-evergreen species. Important plant species growing in these forests include Adina cordifolia9 Haldu), Albizia species(Siris, Kolasiris, Koroi, Sau) Alstonia scholaris(Satiana), Artocarpus chama (Sam), Careya arborea( Kumbhi), Dalbergia species(Sissoo, Medelua), Ficus species (Bot, Bor, Dimoru), Lagerstroemia species (Jarul, Ajar), Mallotu species (Senduri, Joral, Dudhloti) etc.
These forest harbour rich diversity of shrubby and herbaceous ground vegetation. Some of the Reserve Forests also have teak plantations.
Bordering Moist Deciduous Forests in rain shadow areas are found forests which has been referred to as “Dry Forests” by Kanjilal. This type of forests are encountered in the Lumding, Langting, Mailongdisa Reserve Forests. A typical example is the Umananda Island in the middle of Brahmaputra North of Guwahati. Important species include, Aegle marmelos(Bel), Albizia species(Siris), Cassia fistula(Sonaru), Bombax (Simul), Alstonia scholaris(Satiana), Ficus species(Bor), Litsea species(Loban, Bagnola, Mezankori, Honwalu,Digloti) Melia azedarach(Neem), Moringa oleifera(Sajana), Orosylum indicum(Bhatgila), Mallotus species(Senduri), Terminalia species(Hilikha,Bhomora) etc.
Sub-tropical Broad Leaf Hills forests and Sub-tropical Pine forests occur in the districts of Karbi-Anglong and N. C. Hills. Species commonly occurring are Alseodaphne petiolaris(Ban-hanwalu), Antidesma bunius, Betula alnoides, Cleidon speciflorum etc. Higher up pure stands of Pinus kesiya(Khasi-pine) are found particularly in the Hamren sub-division in Karbi-Anglong district.
Grass land and Savannahs are grass dominated biomes and form the major part of vegetation in Kaziranga National Park, Pobitora, Orang, Sonai-Rupai, Laokhowa, Barnadi, Burachapori, Dibru-Saikhowa Wildlife Sanctuaries and some part in Manas National Park. Grasslands support important wildlife population in Assam. Important grasses are Apluda mutica, Phragmatis karka, Sclerostachya fusca, Saccharum species etc. These species grow gregariously at the onset of monsoon and grow even upto 6 meters tall.
Littoral and Swamp forests have almost lost their identity because of biotic pressure on land. Presently sedges and grasses form the largest component of vegetation. Important species include Ageratum conyzoides, Alocasia species, Alpinia species., Amaranthus species., Bacopa species., Blumea species., Bombax species., Crotolaria species. etc.

The Species Rainbow

Because of its physiography, edaphic conditions and a conducive climatic as well as a number of protected areas, Assam boasts of profuse diversity of floristic elements...

Because of its physiography, edaphic conditions and a conducive climatic as well as a number of protected areas, Assam boasts of profuse diversity of floristic elements.
Altogether 4273 species of vascular plants have been recorded in Assam which constitutes 25.12% of total floristic wealth of India. The table below gives an account of various groups of vascular plants.

Table

Name of the Plant Group

No. of Families

No. of Genera

No. of Species

No. of Enfraspecific Taxa

Total

Fern Allies

4

6

40

-

40

Ferns

28

91

311

4

315

Gymnosperms

8

13

21

2

23

Angiosperms Dycolyledous

190

1006

2711

112

2833

Monocolyledons

42

332

1304

38

1072

Total

272

1448

4117

156

4273

In Assam plants belonging to family Poaceae with 303 species form the largest group of vascular plants. Herbaceous plants make 47.83% of the flora followed by trees (19.97%), shrubs(19.67%) and climbers(12.53%) Fern and Fern Allies with 315 and 40 species respectively in Assam represent 25.45% and 35.84% of Indian Pteridophytes. The important species are Psilotum nudum, Huperzia phlegmaria, Huperzia squarrosa and Royal Ferns e.g. Osmunda regalis, Osmunda japonica and Osmunda claytoniana and majestic tree ferns like Angiopteris assamica, Angiopteris erecta, Alsophilia species etc.

Gymnosperms

Assam has 23 species of Gymnosperms and include Cycas pectinata, Podocarpaus neriifolia, P. Wallichianus, Pinus kesia and Genetum...

Assam has 23 species of Gymnosperms and include Cycas pectinata, Podocarpaus neriifolia, P. Wallichianus, Pinus kesia and Genetum gnemon with three varities and G. montanum. These species have restricted distribution but represent plants of high economic importance as source of timber, pulpwood, resins and turpentine and their seed as source of food and medicine and leaves as vegetables.
Angiosperms:
Angiosperms form the largest category of plants in Assam with 3895 species. Assam has also 154 species of primitive Angiosperms better known as “Living fossils” belonging to family Magnoliaceae (19 species), Schizandraceae (1 species), Annonaceae (45 species), Myristicaceae (7 species), Chloranthaceae (2 species) and Lauraceae (80 species). Outside Assam only one “Living Fossils” species have been recorded from Bomdi- La in Arunachal Pradesh.
The important species are Magnolia species., Pachylarnax pleiocarpa, Fissistigma species., Alseodaphne species., Cinnamomum species., Litsea species., Michelia species. etc.
Plants belonging to this category are the most economically important plants of Assam and meet the demand for timber, plywood, pulpwood, furniture, agricultural implements. Leaves of Litsea monopetala, L. cubeba etc. are used for rearing silkworm.

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...

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...

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).

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...

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.
 

Wetlands and Aquatic Plant Diversity

Assam has more fresh water wetlands then any other state in the North Eastern Region. The two major drainage systems of Assam-the Brahmaputra and the Barak...

Assam has more fresh water wetlands then any other state in the North Eastern Region. The two major drainage systems of Assam-the Brahmaputra and the Barak and in the flood plains of these river systems exist patches of marshy depressions and swamps as well as perennial water bodies of varying shape, size and depth called locally as beels, haors, jalah, doloni, hola, pitoni etc. Man made tanks like Joysagar, Sibsagar, Dighalipukhuri, Jorpukhuri, Hazarapukhuri, Rajhuwa Borpukhuri etc. were also dug by ancient Rulers of Assam. There are an estimated 3513 beels and hoars 1,85,623 ponds and tanks and one reservoir in Assam. Deepor beel near Guwahati is a Ramsar site. Besides Deepor beel and some others mentioned above wetlands of importantce are Chandubi, Rata, Sohola, Taralipather, Phokolai, Mer, Sonbeel, Jamjing, Sagunpara, Motapung, Sarlane, Sareswar, Roumari, Khalihamari, Goranga, Sapekhati, Koladuar etc.
The aquatic plants species of Assam belongs to diverse habits and have distinctive characteristics. More than 100 such aquatic species have been identified and they can be described into following broad categories.
1.    Free floating hydrophytes: Eichhornia cressipes, Pistia stratioles, Lemna mino etc.
2.    Suspended submersed hydrophytes: Ceratophyllum demersum, Utricularia gibba etc.
3.    Anchored submerged hydrophytes: Hydrilla, Potomogeton, vallisnaria etc.
4.    Anchored hydrophytes with floating leaves: Nelumbo, Euryle etc.
5.    Anchored hydrophytes with floating shoots: Ludwigia, Ipomea etc.
6.    Emergent amphibious hydrophytes: Sagittaria, Scrirpus.
7.    Wetland hydrophytes: Cyperus, Hygrophylla etc.
 

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