Odisha’s unique location in Peninsular India has blessed it with an interesting assemblage of floral and faunal diversity. With an unindented coastline of nearly 480 km, drained by several large and perennial rivers, altitudinal variation from sea level up to 5000 feet above MSL, varied geography and the confluence of two major biogeographic provinces of India––the Eastern Ghats and Chhotanagpur Plateau–make Odisha a rich biodiversity repository. The state has an area of 1, 55,707 sq km, of which 4.52 % is very dense forest, 13. 67 % is moderately dense forest, 14.13 % comprises open forest and 2.84 % is scrub forest. Of the state’s total geographical area, 32.33 % is covered with forests. This works out to be about 7.21 % of the India’s total forest area (FSI, 2013). These forests vary widely depending on their location but may be broadly classed as moist deciduous, dry deciduous, scrub forest, mangrove forests and patches of semi evergreen forests, especially along the perennial streams and at high altitude areas receiving heavy rainfall. Smaller niche habitats such as savannah, xerophytic habitats, etc also exist as do large wetlands and marshlands. Moist deciduous Sal forest is by far the most dominating in terms of area and expanse across the state. As per Champion and Seth (1968) and Panigrahi (1983b), the vegetation of Odisha comes under four types: (i) Odisha Semi-evergreen forests (ii) Tropical moist deciduous forests (iii) Tropical dry-deciduous forests and (iv) Littoral and Tidal swamp forests.
Biogeographically, the state falls in three zones: Deccan Peninsula (Chotanagpur and Eastern Highlands), Lower Gangetic Plain and East Coast as per classification by Rodgers et al (2002). Meher-Homji (2001) has recognised three phytogeographic regions in the state, i.e., Deccan Plateau, Eastern Ghats and the Coastal Plains. The state is underlain largely by Precambrian rocks. The geological formations reflect a complex of igneous, metamorphic and sedimentary rocks with alluvial and coastal alluvial plains, each giving rise to distinct soil type which range from alluvial (coastal and riverine types) to lateritic and black cotton.
Vegetation in the Eastern Ghats ranges from moist deciduous type in the north to dry deciduous type in the south. These forests are composed of tropical, subtropical and temperate elements along with evergreen types which occur at high elevations.
Protected Areas network: Protected Area is created to provide inviolate habitat for dwindling wildlife. For protection and conservation of biodiversity of the state, a network of 19 wildlife sanctuaries, one national park, one proposed national park, one biosphere reserve, two tiger reserves and three elephant reserves have been declared. The area protected for wildlife management constitutes 4.25 % of the total geographical area of the state. Apart from these, significant areas of forests managed under the Joint Forest Management (JFM) scheme help in maintaining contiguity between protected areas and other forest landscapes. Under the Wildlife Protection Act, 1972 and the Wildlife (Protection) Amendment Act, 2002, four categories of Protected Areas are included: National Parks, Wildlife Sanctuaries, and Community Reserves and Conservation Reserves. Similipal Tiger Reserve and Satkosia Tiger Reserve are the two tiger reserves in the state and a third, Sunabedha Tiger Reserve is proposed. Out of 26 Elephant Reserves (ER) notified in India, 3 are in Odisha. These are the Mayurbhanj ER, Mahanadi ER and Sambalpur ER. Two more elephant reserves, Baitarani and South Odisha, are proposed. There are seven Important Bird Areas (IBAs) in Odisha: Chilika, Mangalajodi, Bhitarkanika, Chandaka-Dampara, Similipal, Satkosia and Sunabeda wildlife sanctuaries.
Flora: Odisha is one of the richest biodiversity regions in Southeast Asia. Saxena and Brahmam (1994-1996) reported 2,727 species of plants under 228 families and 1062 genera of which 2561 species are Indigenous and 166 species are cultivated. This includes 141 species of pteridophytes under 41 families and 66 genera, 10 species of gymnosperms (3 Indigenous species), 124 species of orchids. Out of this 1831 species under 148 families and 747 genera are dicotyledons and 745 species under 37 families and 247 genera are monocotyledons. Odisha is home for over 750 species of medicinal plants. Till date 200-300 species of plants have been added to the list of angiosperms and pteridophytes, bringing the total floral checklist to around 3,000. Later Mishra, 2004 reported 132 species from Odisha. Apart from angiosperms, gymnosperms and pteridophytes the lower cryptogams such as algae, bryophytes and lichens of Odisha were studied by different researcher from time to time. Among the lower group of plants, 45 species of bryophytes (Dash and Saxena, 2009, 2011) and 34 species of lichens (Upreti, 1996) have so far been reported from the state. Later Singh and Kumar, 2012 reported 141 species of lichens from Similipal. Similarly, 105 species of mushrooms have been reported from Eastern Ghats of India which covers some important landscapes of Odisha (Mahapatra et al., 2013). The algal flora of the state consists of brackish water algae-150 species of planktonic form, 14 species of seaweeds/marine algae (Sahoo et al., 2003), 7 species of Seagrasses (Panda et al., 2008) and fresh water forms ~450 species (from different fresh water bodies of the state, Jena et al., 2006a; Jena et al., 2006b; Ratha et al., 2006; Jena and Adhikary, 2007).
Fauna: The broad array of forest types and habitats support a high diversity of fauna. The state harbours terrestrial, fresh water, brackish water and marine fauna. As per Mishra, 2007a, Odisha has record of 87 species of mammals (with recent addition of Asian small-clawed otter- Mohapatra et al., 2014), 473 species of birds, 131 species of reptiles, 27 species of amphibians and more than 600 species of fishes (marine and fresh water). Out of these, 23 species of mammals, 16 species of birds and 17 species of reptiles are considered threatened. The invertebrate faunal composition has been poorly documented and as per updated information available from different sources, the state is home for more than 300 species of Butterflies, 101 species of Odonates (Nair, 2011), 48 species of marine Molluscs, 14 species of Dermaptera (Arthropoda: insecta), 31 species of Isoptera, 32 species of land Molluscs, 48 species of Nematodes and 46 species of Oligocheate as per recent documentation by Zoological Survey of India (ZSI, 2009-10).
Endemic & endangered taxa: Of the estimated 3,200 flowering plants reported from Eastern Ghats of India, about 528 species under 271 genera and 80 families are trees which are distributed in different parts of Odisha, Andhra Pradesh, Tamil Nadu and Karnataka (Sandhyarani et al., 2007). In total 454 species under 243 genera and 78 families are endemic to Eastern Ghats (Reddy et al., 2006a). The list of plant species entering to the endangered status is increasing by the day. The major causes underlying the extinction of species can be attributed to the loss or modification of habitats, targeted poaching or over hunting, lack of protection and natural or man-made hazards. Saxena and Brahmam, 1994-1996 have enlisted 83 species of plants under threatened and endemic categories from the state. Out of them Strobilanthes circarensis, Strobilanthes jeyporensis, Alphonsea maderaspatana, Uvaria uncinata, Lasiococca comberi, Pachystylidium hirsutum, Cajanus cajanifolius, Albizia orissensis, Habenaria panigrahiana var. parviloba, Dimeria mahendragirensis, Dimeria orissae, Oryza jeyporensis, Themeda mooneyii, Themeda saxicola, Eriolaena hookeriana var. viridis, Flacourtia Indica var. innocua, Homonoia intermedia, Aspidopterys tomentosa var. hutchinsonii, Cirrhopetalum panigrahianum, Eria meghasinensis, Hedyotia graminifolia subsp. arenaria, Tephrosia purpurea var. maritima, Liparis vestita subsp. seidenfadenii are considered as endemic to Odisha. Later Mishra, 2007 and 2010 reported two orchids such as Odisha cleistantha and Liparis udaii from Odisha which are also considered endemic to the state.Similarly Cycas sphaerica, Stemona tuberosa, Saraca asoca, Garcinia cowa, Nothopegia heyneana, Acacia donaldii, Acacia tomentosa, Aglaia cucullata, Anaphalis lawii, Dendrobium regium, Dendrobium cathcartii, Dendrobium peguanum, Cassipourea ceylanica, Cryptocoryne ciliata, Bulbophyllum crassipes, Bulbophyllum guttulatum, Bulbophyllum polyrhizum, Eria bambusifolia, Zeuxine lIndleyana, Balanophora polyandra, Bulbostylis subspinescens, Dimorphocalyx glabellus, Gnetum ula, Gnetum montanum, Smilax lanceifolia, Senecio candicans, Psoralea corylifolia, Premna calycina, Lasianthus truncatus, Wendlandia gamblei, are some of the rare, endangered and threatened plants of the state.
As per Dutta, et al., 2005 and Datta-Roy et al., 2013, Barkud limbless skink (Barkudia insularis), Eastern India limbless skink (Sepsophis punctatus), golden gecko (Calodactyloides aureus), south Indian slender gecko (Hemiphyllodactylus aurantiacus), Similipal bush frog (Phillautus similipalensis), etc. are considered as endemic to fauna of Odisha. Among arachnids Peucetia harishankarensis (Biswas, 1975) is also considered to be endemic to Gandhamardan hills. Odisha is regarded as the centre of origin of some earthworm species of genera Lennogaster, Eutyphoeus, Octochaetona, Ramiella, Glyphidrilus and Thatonia (Dash and Saxena 2012). Among the pot-worms (Annelida: Oligochaeta: Microdrili) 77 per cent (seven out of a total of nine species) are endemic to the state.
The species falling under the ‘critically endangered’ category (as described by the IUCN) needing very urgent attention are baer’s pochard (Aythya baeri), white-rumped vulture (Gyps Bengalensis), Indian vulture (Gyps Indicus), red-headed vulture (Sarcogyps calvus) and gharial (Gavialis gangeticus). Some of the species of this category like the forest owlet (Heteroglaux blewitti) and pink-headed duck (Rhodonessa caryophyllacea) have not been sighted in Odisha since over 50 years (ZSI, 1993 and 2009-10).
‘Endangered’ species include tiger (Panthera tigris tigris), fishing cat (Prionailurus viverrinus), Asiatic elephant (Elephas maximus), wild dog (Cuon alpinus), wild buffalo (Bubalus arnee), black-bellied tern (Sterna acuticauda) and Egyptian vulture (Neophron percnopterus), among others.