Tamil Nadu is located in the southernmost part of the country. It has an area of 130,058 km2 which constitutes 3.96% geographical area of the country. It lies between 8◦05’ N- 13◦35’ N latitude and 76◦15’ - 80◦20’ E longtitude. Physiographically, the state can be dived into four major regions namely, Coastal Plains, Eastern Ghats, Central Plateau and Western Ghats. The south-west monsoon feeds the Plateau and the retreating north-east monsoon brings rain to the east coast. The temperature in state ranges from 2◦C in the hills to 45◦C in other areas. The average rainfall ranges from 925mm to 1,170 mm.
The Forest cover in the state based on interpretation of satellite data of assessment year 2013 is 23,844 km2 which is 18.33% of the state’s geographical area. In terms of forest canopy density classes, the state has 2,948 km2 area under very dense forest, 10,697 km2 area under open forest.
1.2 Tree Cover:
The tree cover of the state has been estimated using trees outside forests(ToF) inventory data collected over a period of six years, i.e., 2013. The estimated tree cover in the state is 4,866 km2 which is 3.74% of its geographical area.
1.3 Recorded Forest Area:
The recorded forest area is 22, 877 km2 which constitutes 17.59% of the geographical area of the state. Reserved Forests comprise 19,388 sq.km, Protected Forests 2,183 sq.km and Unclassed Forests constitute 1306 sq.km.
2. Wild Biodiversity of Tamil Nadu:
One sixth of landmass of Tamil Nadu is covered with forests. According to State of forest report 2013 by the Union Territories with reference to total forest cover. The recorded forest area of the state is 22,877 KM² constituting 17.59% of the geographic area. In Tamil Nadu, the moderately dense forest of 10199 KM² and 10697 KM² of open forest, 2948 KM² of very dense forest, and the total forest cover of the State is 23844 KM² constituting 130,058 of geographic.
2.1 Floral diversity:
The Angiosperm diversity of India includes 17,672 species. With 5640 species, Tamil Nadu ranks 1st among all the States in the Country. This includes 533 endemic species, 230 red-listed species, 1559 species of medicinal plants and 260 species of wild relatives of cultivated plant. The Gymnosperm diversity of the country is 64 species of which Tamil Nadu has 4 species of indigenous Gymnosperms and about 60 introduced species. The Pteridophytes diversity of India includes 1022 species of which Tamil Nadu has about 184 species. Tamil Nadu wild plant diversity also includes a vast number of Bryophytes, Likens, Fungi, Algae and Bacteria.
2.2. Faunal Diversity:
The faunal diversity of Tamil Nadu includes 165 species of fresh water Pisces, 76 species of Amphibians, 177 species of reptiles, 454 species of birds and 187 species of mammals. According to the Conservation Assessment and Management Plan (CAMP) reports the red-listed species include 126 species of Pisces, 56 species of Amphibians, 77 species of reptiles, 32 species of birds and 40 species of mammals. The endemic fauna includes 36 species of Amphibians, 63 species of reptiles, 17 species of birds and 24 species of mammals, 42 species of birds and 9 species of reptiles.
3. Protected Areas
Tamil Nadu ranks 14th among all the States and Union Territories of India in terms of protected area. There are 12 wildlife sanctuaries and 12 bird sanctuaries, 5 National Parks, 4 Tiger Reserves, 4 Elephant Reserves and 3 Biosphere Reserves for in situ conservation of wild fauna and flora.
3.1. Biosphere Reserve in Tamil Nadu:
A) Gulf of Mannar Marine National Park
The Gulf of Mannar Marine National Park has the core area of about 560 Sq.KM from Rameswaram to Tutuicorin lying within the Gulf of Mannar Biosphere Reserve covering an area of 10,500 Sq.KM. on the south-east coast of India. It covers the coast of Rameswaram, Tutuicorin, Tirunelveli and Kanyakumari. It is one of the world’s richest regions from marine bio diversity perspective and the first marine Biosphere Reserve in Southeast Asia. The Biosphere Reserve comprises 21 islands with estuaries, mudflats, beaches, forests of the near shore environment, including marine components like algal communities, sea grasses, coral reefs, salt marshes and mangroves. Among the Gulf’s 3600 plant and animal species, there are the globally endangered species Sea Cow (Dugong dugong) and six mangrove species endemic to peninsular India.
The inhabitants are mainly Marakeyars, a local Community principally engaged in fishing. There are about 125 villages along the coastal part of the biosphere reserve which support about 100,000 people . This coupled with dynamite fishing, machanised fishing boats, use of destructive type of fishing nets catching untargeted marine animals and corals and over harvesting of fish makes the efforts of conservation challenging here.
The Gulf of Mannar Marine National Park lies within 08o47’ to 09o15’ N; and 78o12’ to 79o14’ E . The 21 islands are 1 to 10 KM away from the coast of mainland and their extent vary from 0.25 ha to 130 ha Major ecosystem types available are Coral reefs, mudflats, beach, island, shallow water, and mangrove sea grass beds dominated by family like Hydrocharitaceae and Potamogetonaceae and species Halodule uninervis, Cymodocea rotunds, C.Serulata; Coral reefs; mangroves including Rhizophora muctonata, Avicennia alba, Bruguiera gymnorrhiza, Ceriops tagal, Lumnitzera racemosa are also common in the stretch.
The area has all the mangrove species available in India with Pemphis acidula being endemic and all the 11 sea-grasses of India occur here with Enhalus acoroides being endemic. The area supports 147 species of sea-weed Abundance of sea-weeds and sea-grasses in grazing ground attract Sea cow (Dugong dugong) – the flagship species of the protected area. Other marine creatures like Dolphins, sea-horse, sea-cucumber, and sea-anemone are common here. 137 coral reef species form the basis of the ecosystem where 3600 species of plants and animals are associated. Peculiar animal like Balanoglosses living – fossil linking invertebrates and vertebrates is endemic here. Sandy shores of islands is feeding ground for five endangered marine turtles – Green turtle, Olive ridley turtle, Hawksbill turtle, Leatherback turtle and Loggerhead turtle and the first two breed here too. The islands form a good habitat and a stopover between Chilka lake, Point Calimore and Sri lanka for migratory birds. Nearly 180 birds are found here warders and sea-birds being most common. Lesser sand piper, Curlew sandpiper, Little stint are abundant; Rare birds like Red knot, Eastern knot, Crab plovers Bar tailed Godwit, Broad billed Sandpiper, Dunlin, Long toed stint, Red necked phalarope are regulars here. Little tern, Kentish plover, Stone plover, Stone curlew, Lesser crested sterna breed here. Thousands of larger flamingos winter here before returning towards Rann of Kuch
B) Nilgiris Biosphere Reserve
As a follow up of UNESCO’s Man and Biosphere (MAB) programme, the Indian National MAB committee designated Nilgiris Biosphere Reserve, which includes part of two of the ten bio-geographic provinces of India viz. the Western Ghats and Eastern Ghats as the Biosphere Reserve of the country in August 1986 with the following objectives: i) Conservation of biodiversity and their ecological foundations, ii) Bring representative ecosystems under conservation and sustainable use on long term basis, iii) Ensure participation of local inhabitants for effective management and devise means for improving alternate livelihood through sustainable use of natural resources; Integrate scientific research with traditional knowledge of conservation and facilitate education and training as a part of overall management of Biosphere Reserve. The total area of the Bio-sphere reserve is 5520 Sq. K.m out of which major portion of 2537.6 Sq. Kms. is in Tamil Nadu with 1527 Sq. Km. in Karnataka and 1455.4 Sq. Kms. in Kerala. The Bio-sphere Reserve now covers parts of The Nilgiris (Mudumalai WL Sanctuary & National Park (321.1), Mukurthi National Park (78), Nilgiris North (448.3), Nilgiris South (198.8)), Erode (Sathyamangalam (745.9), Erode (49.3)) and Coimbatore (696.2) Districts in Tamil Nadu. The Biosphere lies between 10045’ to 12 015’ North Latitude and 760 10’ to 770 15’ East Longitutudes.
The Biosphere reserve is split into three major zones viz. Core Zone, Manipulation forestry Zone, Tourism Zone and Restoration Zone.The break up for the above four zones are as follows:Core Zone 1240.3 Sq. Km (22.5%) , Manipulation forestry Zone: 3238.7 Sq.Km (58.6%). , Tourism Zone: 335.0 Sq. Km.(6.1%) , Restoration Zone : 706.4 Sq. Km. (12.8%). The sanctuaries covered are Mudumalai Wildlife Sanctuary and Mukurthi National Park.
The following is the important aspects of the Nilgiris Biosphere Reserve:
The Nilgiris Biosphere Reserves comprises of substantial un-spoilt areas of Natural vegetation ranging from dry scrub to evergreen forests and swamps thus contributing to highest bio-diversity. The altitude ranging from 250 m in the Coimbatore and Calicut plains to 2500 m. in the upper Nilgiris and corresponding climatic gradients support and nourish the different vegetation types. The Nilgiris Biosphere Reserve is very rich in plant diversity. About 3300 species, 1232 are endemic to the Nilgiris Biosphere Reserve. The genus Baeolepis is exclusively endemic to the Nilgiris. Some of the plants entirely restricted to the Nilgiris Biosphere Reserve include species of Adenoon, Calacanthus, Baeolepis, Frerea, Jarodina, Wagotea, Poeciloneuron, etc. Of the 175 species of archids found here, 8 are endemic to the Nilgiris Biosphere Reserve. These include endemic and endangered species of Vanda, Liparis, Bulbophyllum, Spiranthes and Thrixspermum. The sholas of the Nilgiris Biosphere Reserve area treasure house of rare plant species. The fauna of the Nilgiris Biosphere Reserve includes over 100 species of mammals, 350 species of birds, 80 species of reptiles; about 39 species of fish, 31 amphibians, 60 species of reptiles, 300 species of butterflies and innumerable invertebrates are endemic to the Western Ghats.
C) Agasthiyarmalai Biosphere Reserve
The total area of the Bio-sphere reserve is 3500.36 Sq. k.m out of which 1828 Sq. kms. is in Kerala and 1672.36 Sq. Kms. is in Tamil Nadu. The Bio-sphere Reserve now covers parts of Tirunelveli and Kanyakumari District in Tamil Nadu and Thiruvanantha puram, Kollam and Pathanamthitta District in Kerala. The Biosphere lies between 80 8’ to 9010’ North Latitude and 76052’ to 770 34’ East Longitutudes.
The Biosphere reserve is split into three major zones viz. Core Zone, Buffer Zone and Transition Zone In Kerala the break up for the above three zones are as follows: Core Zone : 352 Sq. Km, Buffer Zone: 691 Sq. Km, Transition Zone 1828 Sq. Km. The sanctuaries covered are Neyyar, Peppara and Shenguruny sanctuaries. In Tamil Nadu the break up for the above three zones are as follows: Core Zone: 691 Sq. km , Buffer Zone: 198.36 Sq. km Transition1672.36 Sq. km. The sanctuaries covered are Kalakad Mundanthurai Tiger Reserve.
4. Forest Types of Tamil Nadu
Tamil Nadu has a total extent of 22,520 sq.km of forests, which is present in 9 major forest types according to the Champion and Seth’s classification of forest types of the country. Tamil Nadu’s forests are largely deciduous and thorn types and these two major types account for 87.30 % of the total forest area. According to Champion and Seth, forest type may be defined as a unit of vegetation, which possesses (broad) characteristics in physiognomy and structure sufficiently pronounced to permit of its differentiation from other such units. This is irrespective of physiographic, edaphic or biotic factors. It is selected in the first place subjectively from the every-varying cover of vegetation, with boundaries arbitrarily imposed on where are in fact gradual changes (clines or continua). Since these forest types have a bearing on the practice of scientific forestry and practical utility is indeed the main reason for distinguishing them, necessarily greater importance is placed on the main tree layers or on the most emergent vegetation. Distinctions based on shrub and ground flora, characteristic of much recent ecological work on the vegetation of India, have necessarily been given a subordinate place. The major type-groups area subdivided into types on a geographic basis since a recognizable type group varies somewhat with locality owing to differences in floristic and minor variations in climate and site occurring within the range associated with each group-type as a whole.
i) Southern Hilltop Evergreen Forests:
This is an inferior condition of the tropical evergreen forests occurring on the upper slopes and tops of hills exposed to winds. The area under this type is not much. This forest is an edaphic climax type 1A/C3 and is found between 1,200 and 1,500 m. Unfavorable conditions on upper slopes and top of hills and steep slopes lower down under strong winds, shallow soils stunt the growth to not more than 10 m though the rainfall is over 4,500 mm. This type is found in Muthukuzhivayal of Kalkkadu Mundanthurai Tiger Reserve (KMTR). This forest type occurs with grasslands as shola grassland type similar what we see in Nilgiris. There is no record of felling in this 3 forest in past system of management. Vast stretches of these forests must have been submerged in the Upper Kodayar Reservoir during construction.
ii) West Coast Tropical Evergreen Forests:
Wet evergreen forests are confined to Western Ghats, where rainfall is generally above 2000 mm. Considering the distribution pattern of certain characteristic species that reflect the climatic variations, especially temperature, the forests are further subdivided into low (<800 m) and medium(800-1450m) elevation.
iii) West Coast Semi Evergreen Forests:
This type occurs in Kodaikanal plateau in moist protected valleys (sholas) between 100 and 1900 m in Tiger shola, Picnic shola etc. The annual rainfall received varies from 1000 to 1500 mm. This type of forests occurs in transition zone between west coast tropical evergreen forests and dry deciduous forests with even mixture of both types. This type of forests are represented in Pambar R.F., part of Sengalvarayar R.F., part of Kodaikanal Range, Gundar valley part, Ampthill down R.F., Bombay Shola, and Vandaravu and to narrow width on either side along Pulavahiar and Konalar etc in Kodaikanal division.
iv) Tirunelveli Semi Evergreen Forests:
They are ecotones, as they are found between evergreen and dry deciduous forests. They are also described as transitional forests. The steep decrease in rainfall and rapid increase in the dry months towards the east of the reserve drastically changes the nature of the vegetation from wet type to dry type. However, a narrow strip between the two types along the eastern slope, which receives rainfall between 1500 and 2000 mm, serves as a transition zone with some typical species. The forest type is unique to KMTR and occurs relatively in a narrow strip on the Papanasam hills between moist deciduous forests and southern tropical wet evergreen forest in the Papanasam R.F, Kalakad R.F and Thalaiodai. The elements are a mix of evergreen and decidous . The elevation ranges sometimes up to 1,000 m.
v) West Coast Secondary Evergreen Dipterocarp Forest:
Nearly pure forest of evergreen Dipterocarpacae of relatively poor development, but with an even and typically dense canopy, without a definite middle storey, but with undergrowth of evergreen shrubs are encountered on the coastal plain below the Western Ghats. Locality factors include a high rainfall of over 2,500 mm and a hot equable climate typified stiff red tropical soils often lateritic on fairly level country intersected by network of eroded depressions.
vi) Moist Teak Bearing Forest:
This is a small isolated forest and supports only one type of forests viz., the “slightly moist teak forests”. Typical rainfall 1,600 to 2,500 mm.; deep loamy soils fair to medium (10 to 25) percentage of teak; dense undergrowth; fair, but patchy natural regeneration; fires rare; light grazing.
vii) Southern Moist Mixed Deciduous Forests:
These forests occur on the outer slopes up to an elevation of about 500 m. The main species are deciduous, though some evergreen species are also present. Natural teak forms a very low proportion. This type occupies damp valleys, in cooler patches in the lower hills and on high ground with shallow or porous soils.
viii) Southern Secondary Moist Mixed Deciduous Forests:
The chief feature of the moist deciduous forests is a leafless period in the dry season, when the upper canopy is almost entirely leafless though there is a good sprouting of evergreens in the under wood. This type of forests is restricted between elevations of 500 and 1000 m in RF part below Oothu, Pambar R.F., Amburuvi R.F. of Periyakulam range, in parts of Kodaikanal range, southern portions of Gundar valley R.F., and Gundar valley extension R.F. In these forests, Calamus canes are restricted to wet ground. Epiphytes and climbers are abundant and large.
ix) Littoral Forests: Littoral Forest:
Termed also as beach and dune forest, it is located all round the coast, wherever a fair width of sandy beach occurs, including sandy bars on the sea face of the river deltas. The most characteristic species is the tall evergreen, but very light foliaged Casuarina, which often forms an almost pure fringe on sandy beaches and dune along the sea face. Scattered smaller evergreen trees occur with fewer deciduous trees and these in the absence of Causarina from the dominant canopy. There are numerous shrubs, and where the undergrowth is light, maritime grasses (Spinifex etc.) and surface creepers are conspicuous, binding the sand.
x) Tidal Swamp Forests :
“Tidal Forests” vary so much in such short distances that a general description is difficult. The finest forest is found on the ground, which is flooded at every high tide with only moderately blackish water and is an evergreen forest. There may be an under wood of younger trees closed high such as Ceriops, two storied forests being of common occurrence owing to the prevalence of trees whose maximum height is only 5 to 10 m mixed with others capable of further development. Rhizophoraceae are almost confined to these areas and are most typical. Their special habit is the newly deposited mud banks submerged by tides every day. In addition, there are a few genera, each usually with several species belonging to a considerable number of families, which are specially adopted to the unusual conditions, like Lythraceae (Sonneratia), Verbenaceae (Avicennia) Euphbiaceae (Excoecaria) Leguminosae (Cynometra).
xi) Mangrove Scrub:
This type is found in portions of Killai R.F., Pitchavaram R.F., and Pitchavaram Extension R.F. in Villupuram division, towards the interior, away from the fringes of lagoons, which is subject to inundation only occasionally. This is more or less a dense forest of low height (2 to 5 m tall) often reduced by biotic factors. The species are few and markedly gregarious; all evergreen with entire leathery leaves Vivipary is very common.
xii) Mangrove Forests:
This is typically a closed evergreen forest of moderate height (up to 10 m) consisting of trees specially adopted to survive on tidal mud which is permanently wet with salt water and Submerged at every tide, stilt roots are very typical, notably in Rhizophora; so also leathery and entire leaves and vivipary. This type occurs all along the fringes of lagoons and islands. This type is found in portions of Killai R.F., Pitchavaram R.F., and Pitchavaram Extension R.F., along the bank of lagoons, maze of tidal creeks, and in the small islands around the estuary in Villupuram division.
xiii) Sub-Montane Hill Valley Swamp Forest:
Irregular forests of a limited number of mainly evergreen species, able to withstand the wetness of the sites occupied, the trees here are usually low-crowned and branchy and there is often a dense growth of Calamus, whilst Ficus and monocotyledons such as Alpinia often from the undergrowth. They occur in narrow strips of Gudalur valley of the Nilgiris in Tamil Nadu.
xiv) Riparian Fringing Forests:
This type occurs on either side of all the rivers and natural drainage lines. This is a edaphic formation. They are strips and islands of evergreen forests in the midst of dry deciduous forests. They contain the elements of wet evergreen forests as can be seen near Thalaiyanai in Kalakad. Riparian fringing forests are distinct and easily identifiable in the setting of dry deciduous and moist deciduous forests. Riparian fringing forests are also called as Gallery forests. Most of the amphibians are confined to this zone. Many reptiles like Dasia halianus is confined tothis zone in the Mundanthurai plateau along S e r v a l a r River. Nilgiri Langur prefers this habitat along the Servalar river.
xv) Dry Teak Bearing Forest:
Termed as dry teak forest and dry mixed forest with teak poles, canopy in this type is fairly complete and the trees are sufficiently large, tall and well grown to yield sawn teak timber of 3rd and 4th site quality. Majority of the tree species, occurring in this type coppice freely when felled. It is met with widely in South India extending a few degrees north of the tropic, where rainfall of 1,000 to 1,250 mm is recorded.
xvi) Dry red sanders bearing forests:
This forest type is mostly found in Cuddappah, Kurnoolm, Chittoor and Nellore divisions of Andhra Pradesh. However, in Chennai, Vellore, Dharmapuri circles vast extent of red sanders plantations has been raised. In Tiruvallur and Chengalpattu districts, this species might have existed in the past in the natural conditions.
xvii) The Southern Tropical Dry mixed Deciduous Forests:
This forest of this type is found at elevations of 600 to 1200 m, with precipitation varying from 800 to 1500 mm; confined in Ayyakudi Ex-zamin forests, S.S.R.F. Mulayar R.F., Perumalmalai R.F, Shengaivarayar R.F, Adukkam, Varattarkanal R.F, all of Kodaikanal division. This type of forests is confined in shallow soil, well-drained hillside or undulating ground. Both top canopy and lower canopy are deciduous. Bamboos are often absent and usually of poor quality when present. The forests are burnt annually.
xviii) Southern Tropical Thorn Forests:
This is a degraded type of forest found distributed in drier parts of Tamil Nadu like Chengalpattu, parts of North Arcot, South Arcot, Tiruchirapalli and Madurai. This is an extremely xerophytic type of vegetation found in the plains and low hills. The rainfall is around 500 to 700 mm, with the bulk coming in October – November being closest to cultivation, this type of forest suffered most from overgrazing and injuries by man. The surface soil is hard and of low permeability, and what little rainfall is there runs off the surface of the sloppy grounds rapidly, with the result that although copious regeneration is fair, natural regeneration is absent.
xix) Tropical Dry Evergreen Forest:
The thickest forests are located on a series of low sand dunes in the western part of the Point Calimere Sanctuary. Towards the east, these forests gradually thin out to a scrubland interspersed with open grasslands. Manilkara hexandra, locally called Palai, is the dominant Dry Evergreen species in the sanctuary. It grows to a height of 40 feet or more and is an important source of food for the fruit eating birds. Other important top canopy trees include species such as Syzgium cumini, Pongamia pinnata, Ficus benghalensis, Ficus infectoriaand Ficus microcarpa.
xx) Tropical Dry Evergreen Scrub:
This type of forest is the result of climax forest degradation causing disappearance of the trees; the remanents are throny scrubs. This type of forest is unique in Tamil Nadu and found to occur only in Chengalpattu district in the forest of Vandalur and Navalur. The main species are Memecylonedule, Zizyphusglabrata , Dichrostachys cinerea etc.
xxi) Forests Nilgiri Sub-Tropical Hill Forest:
This type occurs below the frost line in the lower levels of the plateau and on the upper reaches of the slopes between 1000 and 1800 meters altitude. The average height ranges from 29 meters to 30 meters and these increases progressively towards the lower elevations especially on the southwestern and wester face of the plateau in the tract cover looking the Nilgiris-Wynad (presently in Gudalur division).
xxii) Southern Montane Wet Temperate Forests:
This forest type occurs above 1,524 m as continuous expanses of the evergreen forests at sheltered faces and moist depressions of peaks. Common ones here are shola tree species not exceeding 6 m with densely clothed lichens, mosses and ferns such as Byrsophyllum tetranddrum, Canthium neilgherrense, Clausena heptaphylla, Eugenia mabaeoides, Euphiorbia santapaui, Olea polygama, Polyscias acuminata and Rapanaea wighitiana Thistype of forest occurs in the upper Palanis Plateau from1700-2450 m. elevation where the rainfall is 1200 mm.
Sources: Tamil Nadu Forest Department and FIS-2013