TAMIL NADU – BIODIVERSITY

THE FLORA OF THE NILGIRIS AND PULNEY HILL TOPS

The early explorers evinced keen interest in documenting the floral assemblage of the hills as well. The first account of the flora of the Pulney Hills was published by Robert Wight in the Journal of the Madras Literary and Scientific Society in 1837. Twenty one years later Col. Beddome published in the same journal, a list of 700 species collected from the Pulneys and he also wrote an account of the flora of the Nilgiris for the Nilgiri District Manual. Mrs. Mackay's charmingly wrote on Wild flowers of Kodaikanal. Later, P.F. Fyson in 1915 published 'The Flora of the Nilgiri and Pulney Hill tops' with 286 illustrated pages and 483 species. Of the species described by Fyson, 430 were indigenous to the Nilgiris and Pulneys hill tops. Out of this, 44 were exclusively found in the Nilgiris and 29 in the Pulneys. A supplement followed in 1921 with species from the lower elevations and notes on the Shervaroy hills. This was followed in 1932 by 'The Flora of the South Indian Hill Stations' covering 877 species. His wife Diana Ruth Fyson illustrated the book by contributing nearly 320 of the 611 plates in it.

TAMIL NADU – BIODIVERSITY

Tamil Nadu, the southernmost State of the Indian peninsula is spread over 1,30,058 sq.km land mass and accounts for about 4 % of the total area of the country. It lies between 8° 05' and 13° 34' North latitudes and 76° 14' and 80° 21' East longitudes. The topography of Tamil Nadu broadly consists of the coastal plains in the east, uplands and hills as one proceeds westwards. The central plains account for more than half the area of the State. The geographical area of the State has a roughly rhomboidal appearance with the longer diagonal of it stretching from Pulicat Lake in the north to Kanniyakumari in the south and the shorter diagonal from Gudalur in the west to Point Calimere in the east.

Tamil Nadu is endowed with rich biodiversity, right from marine coastal systems in the Gulf of Mannar to terrestrial evergreen forests in the Western Ghats. Tamil Nadu shares the Western Ghats with the States of Kerala, Karnataka, Goa, Maharashtra and Gujarat. It shares the Eastern Ghats with the States of Andhra Pradesh and Orissa.

THE PIONEERS IN SEARCH OF THE PRESIDENCY'S FLORA

Botanical description of the Presidency's vegetation owe to the hard and dedicated work of few explorers, some of whom served as early foresters here. J. S. Gamble was requested to undertake the preparation of a Flora of the Presidency of Madras in 1912, a task for which he was remarkably well qualified owing to the exceptional knowledge of the flora, he had acquired during his long service in the Presidency as Conservator of Forests. During the course of his extensive and careful tours, he made very complete collection of plants of the Presidency, formed and maintained a private herbarium, which he subsequently presented to the Royal Botanical Gardens at Kew, England.

The first part of the 'Flora of the Presidency of Madras'(Ranunculaceae to Opiliaceae), consisting of 200 pages, was published in November 1915 and the draft of the botanical portion of the first 132 pages was prepared by S. T. Dunn, as explained by Gamble in his introduction to this part, since Gamble had not at that time completed his Malayan work. The remainder of this part and the editing of the whole and the preparation of Parts II to VII inclusive were undertaken entirely by Gamble. Part II was published in 1918 and was followed by Part III in 1919, Parts IV, V, VI and VII in 1921, 1923, 1924 and 1925, respectively. This mammoth task could not be completed in the lifetime of Gamble and Part VII was published very shortly after his death on October 16th 1925. Publication of this part carried the compilation of this work to the end of the Euphorbiaceae. With the consent of the Government of India and of Mrs. Gamble, further continuation of the 'Flora' was entrusted to C. E. C. Fischer, who was also formerly a member of the Imperial Forest Service and the then Assistant for India at the Kew Gardens. With many years of experience in the Presidency and his exceptional knowledge of the flora, the onerous task of publication of Parts VIII, IX and X was completed in 1928, 1931 and 1934, respectively.

THE STATE'S FLORAL DIVERSITY

The Indian region with a total area of about 328 million ha is very rich in biological diversity. It is estimated that about 45,000 species of plants occur in the country. The vascular flora, which forms the conspicuous vegetation cover itself comprises 15,000 species, of which more than 60% are endemic and have so far not been reported from anywhere else in the world. The total plant wealth of the country includes not only the usually large, showy-flowered vascular plants, but a large number of non-flowering plants, viz. ferns, liverworts, algae and fungi. The wild relatives of crop plants along with related species as well as the species of economic plants (estimated to be over 150) are in themselves very valuable gene pool. Inventorization of floral and faunal distribution continued under the aegis of the national institutes of Botanical Survey of India and the Zoological Survey of India across the country and with every subsequent survey, new and unknown species of plants and animals came to be identified and added to the list. Tamil Nadu's diversity was also surveyed during the course of investigations by researchers from other scientific institutions. Gamble (1935) enumerated 4,516 species in the then Madras Presidency, while after the State's reorganization 2,260 species belonging to 983 genera and 173 families have been described in Tamil Nadu and Carnatic region (Mathew et al. 1981). Besides, they have also reported 111 species of Pteridophytes from 59 genera and 11 species of gymnosperms from 9 genera and 5 families. Subbarayalu and Velmurugan (1999) have described 202 species under different IUCN categories of threat. Of this 45 species are endangered, 53 possibly extinct, 29 vulnerable and 75 rare.

The Angiosperm diversity of India includes 17,672 species. With 5,640 species of flowering plants, Tamil Nadu ranks first among the States in the country in angiosperm diversity. It accounts for nearly one-third of the total flora of India. This includes 533 endemic species, 230 red-listed species, 1,559 species of medicinal plants and 260 species of wild relatives of cultivated plants. The gymnosperm diversity of the country is 64 species, of which four species are indigenous Gymnosperms and the rest are introduced species. The pteridophyte diversity of India includes 1,022 species of which Tamil Nadu has about 184 species. Tamil Nadu's wild plant diversity also includes vast number of bryophytes, lichens, fungi, algae and bacteria. The analysis provided the total number of plants in Polypetalae, Gamopetalae and Monochlamydae to be 1,944, 1,720 and 642, respectively. Distribution of plants in different plant taxa shows there are a total of 4,306 dicots and 1,241 monocots.

FOREST TYPES OF TAMIL NADU

The physiography of the country has been classified into ten bio geographic zones, of which two viz., the Coramandel or the East Coast and the Western Ghats are occurring in the State. Naturally, landmass of the State falls under two natural divisions' viz., the eastern coastal plain and the hilly region along the north and the west. In view of the vast physical and climatic variations in the landscape, the State encounters diverse types of vegetation. Among the Southern states, Tamil Nadu contains the maximum number of 9 of the total of 16 major forest types recognized in India by Champion and Seth. Within the major types, 48 sub types of forests are found in Tamil Nadu. It will be interesting to study the vegetation and forest types in the zone in which they are present.

(i) The coastal plain It can be sub divided into (a) the Coramandel plain, comprising the districts of Chengalpet, Viluppuram, Cuddalore, (b) the Alluvial plains of the Cauvery delta extending over the composite Thanjavur and part of Trichirapalli districts,(c) the dry Southern plains in Madurai, Ramanathapuram, Kanyakumari and Tirunelveli and (d) the inner plains comprising districts of Dharmapuri, Salem, Vellore and Madurai districts. Along the coast at places like Mahabalipuram, Mandapam and Kanniyakumari, outcrops of rocky head lands are present. A narrow belt of sand dunes rising to about 10m is found on the Toothukudi coast. Further south in Toothukudi, red sand hills locally known as “Teri” rises to 50 m above mean sea level (MSL). Typical coral reefs occur at Pamban islands at the head of the Gulf of Mannar on the east coast.Along the coast, here and there, there are but a few lakes, lagoons and marshy lands. The Buckingham canal, which connects river Krishna in Andhra Pradesh with Chennai, passes through some of them. Veeranam lake in Chenglepet is one of the largest lakes in the State

(ii) The hilly region along the North and the West Along the whole length of the western part, at a distance from the sea varying from 80 to 160 km runs the range of Western Ghats, a steep and rugged mass averaging 1220m above MSL and rising to 2554 m at Mukurti and 2637 m at Doddabetta in Nilgiris. It has tropical evergreen, semi-evergreen and deciduous forests, as well as savannahs intermixed with cultivated lands and settled areas in the valleys. The Eastern Ghats from Andhra Pradesh cut across the State to meet the Nilgiri hils. The 'Palghat gap' of about 30 km width is the only marked break in the Western Ghats. To the south of this gap, the range is called Anamalai and Cardamom hills. On the east of Western Ghats are Palni hills, which are an offshoot of Anamalais. Other prominent groups of hills are Javadis, Shervaroys, Chitteris, Kolli hills, Kalrayans and Pachamalais. All these form a chain of low, flat-topped hills. Nilgiris and Anamalais are hill groups with the maximum height. Slopes of the Western Ghats are the sources of many rivers, which flow eastwards towards the Bay of Bengal. Of these, Cauvery, Moyar, Bhavani, Amaravati, Chittar and Tamaraparani are perennial rivers, whereas Vellar, Noyyal, Suruli, Gundar and Vaipar are non-perennial ones. All these rivers are rain-fed, unlike the snow-fed ones of the Himalayas. Cauvery, which rises from Brahmagiri in Coorg is the longest river of the State. It travels the entire breadth of Tamil Nadu and forms a large delta at its mouth in the erstwhile composite Thanjavur district making the region the 'granary of Southern India'. Tamiraparani also has deltaic deposits at its mouth in Toothukudi district.

MAJOR FOREST TYPE GROUPS IN THE STATE IS AS BELOW

FOREST GROUP	FOREST TYPE
1	Tropical wet evergreen
2	Tropical semi evergreen
3	Tropical moist deciduous
4	Littoral and swamp
5	Tropical dry deciduous
6	Tropical thorn
7	Tropical dry evergreen
8	Sub-Tropical broad-leaved hill
9	Montane wet temperate

It is seen that the tropical deciduous and thorn forests constitute the majority of the forest area in the State and account for nearly 60% of the total forests.

VEGETATION AND ITS DISTRIBUTION

It is considered worthwhile to provide the reader with the glimpse of different forest types and their occurrence in the State, besides the chief species that constitute those forests to enable them to obtain a better understanding of the management history that was recorded in the different forest types over the times. The great plant wealth and diversity of Tamil Nadu is due to the immense variety of climate, altitude, aspect, gradient and other edaphic factors. Vegetation of the State can be broadly divided into four categories, which are described in the following pages.

Coastal vegetation
Island vegetation

III. Vegetation of the interior plains

Vegetation of the hills and Mountains
Coastal Vegetation

The entire cost of Tamil Nadu is chiefly sandy with outcrops of rocky headlands at Mahabalipuram, Mandapam and Kanniyakumari. There are some tidal creeks and mud flats at the riverine mouths of which the Vellar and Cauvery complex are significant. At the mouths of the rivers and numerous creeks, extensive mud and saline flats with the formation of pro estuarine vegetation is noticeable, particularly at Pichavaram, Toothukudi and adjoining areas. Coral reefs are found at Mandapam, Toothukudi and Kanniyakumari, where the substratum is hard with high percentage of calcium carbonate. The coastal vegetation can be sub divided into Strand, Estuarine type and Coastal tropical dry evergreen forest types (Nair and Vivekanandan 1983).

A) STRAND SAND

In this type, soils are coarse sandy with the pH ranging from 6.7 to 7.3. The vegetation here has four zones, with each zone characterized by certain species.

1) OPEN PIONEER ZONE

Cyperus arenarikus, Ipomea pescarprae, Lannaea sarmentosa, Polycarpaea corymbosa, Sesuvium portulacastrum, Spinifix littorreus, Tribulus terrestris, etc. are common.

2) CLOSED HERBACEOUS ZONE

Soils are found to be containing fine sand or rarely coarse sand. pH ranges from 7 to 7.2. Alternanthera pungens, Atriplex repens, Blumea oblique, Boerhavia diffusa, Borreria articularis, Chloris barbate, Croton bonplandiamum, Euphorbia sp., etc. are the commonly recorded species.

3) MIDDLE MIXED ZONE OR BUSHY ZONE

Soils are loamy sand with the pH typically ranging from 7 to 7.2. Caesalpinia bonduc, Calotropis gigantea, Carissa spinarum, Cassia auriculata, Clerodendron inerme, Indigofera oblongifolia, Jatropha glandulifera, Tephrosia purpurea, Waltheria indica, etc. are commonly found.

4) INNER WOODLAND ZONE

Soils are loamy sand or clayey loam with the pH ranging from neutral to 7.3 with Borassus flabellifer, Calophyllum inophyllum, Carissa spinarum, Drypetes sepiaria, Mimusops elengi, Pandanus fascicularis, Phoenix pusilla and Prosopis cineraria. At some places Anacardium occidentale, Casuarina equisetifolia and Cocos nucifera are cultivated.

B) SAND ROCK THE VEGETATION CAN BE CLASSIFIED UNDER FOUR HEADS.

1) EXPOSED ROCKY LOW LYING REEFS

Soils have a pseudo-crumb structure and rich calcium carbonate content (68.81%) with the pH around 7.8. The marine angiosperms usually found here include Cymodocea rotundata, C. serrulata, Enhalus acoroides, Halophita ovalis, H.stipulacea and Syringidium isoetifolium.

2) ROCKY RELIEF

It consists of mostly exposed rocky lateritic boundaries with thin mantle of sand in crevices of weathered surfaces. This type is found at Kanniyakumari and its neighbourhood. Atriplex repens, Boerhaavia diffusa, Cenchrus ciliaris, Chloris virgata, Chloraphytum laxum,, Cyperus pachyrrhizhus, Phyllanthus maderaspatensis, Scilla hyacinthine, Tridax procumbens etc. are commonly found.

3) LESS ROCKY TO GRAVELLY OR SANDY AREAS

The soil is represented by coarse sand with the pH value falling between 6 and 7. Aristolochia bracteolata, Atriplelx repens, Cassia nigrcans, Ipomoea pescaprae, Lannea sarmentosa, Polycarpaea corymbosa, Portulaca quadrifida, P.pilosa, Urginea congesta, etc. are the common plants.

4) INNER WOODLAND ZONE

Lantana camara var, aculeata, Lepisanthes tetraphylla, Sapindus emarginta etc. are the commonly recorded species in this zone.

c) Strand Coral Four zones are recognized in this sub-type. They are

i) Open pioneer zone

Soils are coarse sand. pH value varies from 6.1 to 7.2 Avicennia officinalis, Atriplex repens and Salicornia brachiata are commonly found.

II) RAISED CORAL ROCKS WITH CRANNIES

Soils are coral sand. pH ranges from 7.2 to 8.2 .Halopyrum mucronatum, Polycarpaea spicata and Sporobolus tremulus are the common species.

III) CLOSED HERBACEOUS ZONE

Soils are coarse sand mixed with coral sand. pH varies between 7 and 7.6. Eragrostis riparia, Fimbristylis eymosa, Scavola plumieri, Sporobolus spicatus and S.virginicus are common.

IV) INNER WOODLAND ZONE

Plant group characteristics of this zone are similar to those of inner woodland zone described under 'strand sand'.

TROPICAL DRY EVERGREEN FOREST

Restricted to the coastal region from Tirunelveli northwards is the tropical dry evergreen forest. These are low forests with trees measuring 9-12 m tall, forming a complete evergreen canopy. Leaves are coriaceous and the crowns spreading. The forest may have deciduous elements, which is without a marked canopy layer. Common woody plants found in such forests are Atalantia monophylla, Calophyllum inophyllum, Canthium parviflorum, Carissa spinarum, Erythroxylum monogynum, Lannea cooromandelica, Manilkara hexandra, Mimusops elengi, Large climbers are Canavalia gladiata C.virosa, Mucuna atropurpurea and M.pruriens. Parasites like Cassytha filiformis, Dendrophthoe falcata and Viscum orientale are frequently found. Vanda tessellatta is a common epiphytic orchid. This forest type is found in Vedaranyam and Talainayar RF. Further, following sub types are recognizable.

Sl No	Forest Sub Type	Location
1	Southern Tropical dry evergreen forests (7/C1)	GNP,Hosur,Tiruppattur, Vellore, Sivagangai, Point Calimere
2	Tropical Dry Evergreen Forests Carnatic Evergreen Forests (7/C1)	Tiruvannamalai
3	Tropical Dry Evergreen Forests Hill Forests (7A/C2)	Tiruvannamalai, Tiruppatur
4	Southern tropical evergreen scrub forests (7/DS1)	Chengalpet, Vellore

ISLAND VEGETATION

Vegetation of Rameswaram and Krusadai group of islands consists of tropical thorny umbrella type, degraded to low open scrub formation due to severe biotic and climatic causes. It can be mainly grouped under two categories namely, mangrove and strand formations. Based on their edaphic features they can be further subdivided into the following distinct units.

FORESHORE SANDY HABITAT

The soils in the island shores are loose and light, coarse sandy and coloured dull white. Their main constituents are shell fragments and disintegrated coral rocks. Atriplex repens, Ipomoea pescaprae (dominating strand creepers), Seaveola plumeria, Sesuvium portulacastrum and Spinifix littorreus are commonly found in such areas.

INLAND SANDY HABITAT

The soils resemble that of foreshore sandy habitat, but better protected than it and support more luxuriant vegetation. Borassus flabellifer, Breynia rhamnoides, Calotropis gigantea, Cassytha filiformis, Clerodendron inerme, Dodonea viscosa, Indigofera oblongifolia, Pandanus sp., Salvadora persica, Thespesia populnea are the common plants encountered here.

SALT MARSH HABITAT

Salt marshes are usually with a white incrustation of salts. The soil contains very high total soluble salts and sodium chloride contents. Apluda mutica, Arthocnemum spp., Atriplex repens, Avicennia officinalis, Eremopogon foveolatus, Fimbristylis sp., Salicorina sp., Sporobolus tremulus and Suaeda species are common.

MANGROVE HABITAT

The soil is semi muddy coral sand with some cohesion. It contains hardy roots and decomposing foliage. Avicennia officinalis, Bruguiera conjugata, Ceriops tagal, Luminizera sp. and Rhizophora sp. are common. Sometimes, when muddy shore is replaced by coral stone, Pemphis acidula (indicator for coral rock) is seen adjacent to the mangrove zone.

MARITIME HABITAT

The soil is sandy with some decomposed and decomposing organic matter from the flora and fauna present there. Numerous algae and a few phanerogams are found. Enhalus acoroides, Cymodocea spp and Halophila spp are encountered.

III. VEGETATION OF THE INTERIOR PLAINS

These types of forests are found in the lower plains, Eastern Ghat hills and the low land outer slopes of the Western Ghats as well. Several sub-types are recognizable.

TROPICAL THORN FORESTS

These forests are found from plains up to 400 m. The common trees of the top storey are Acacia ferruginea, Acacia leucophloea, Albizz ia amara, Azadirachta indica, Canthium dicocum, Chloroxylon swietenia, Santalum album, Tamarindus indica. The second storey consists of Acacia latronum, Acacia sundra, Balsamodendron berryi, Bauhinia racemosa, Dichrostachys cinerea, Erythro xylon, monogynum, Wrightia tinctoria and shrubs like Calotropis procera, Capparis sepiaria, Carissa carandas, Cassia auriculata. The climbers include Abrus precatorius, Acacia intsia, Acacia pennata, Combretum ovalifolium, Derris scandens, Maerua arenaria, Pterolobium indicum, Sarcostemna brevistigma Many sub types within the major type are recognized in various parts the State. They are

Sl No	FOREST SUB TYPE	LOCATION
1	Southern Tropical Thorn Forests (6A/C1)	Tiruvannamalai,Chengalpet,Tirupattur,Vellore, Kanniyakumari, Sathyamangalam,Nilgirisouth Erode, Trichy , Sivagangai
2	Southern Tropical Carnatic Umbrella thorn forests (6A/C2)	Theni, KMTR, Trichy, Dindigul, Madurai,Sivagangai, Thoothukudi
3	Aeolian formations (Theri) - (6A/C2 DS WE)	Tirunelveli, Thoothukudi, Kanniyakumari, Kanniyakumari, Nilgiri North, Vellore,
4	Southern Thorn Scrub Forests (6A/DS1)	Tiruvannamalai,Chengalpet,Tiruppattur, KMTR, Trichy, Thoothukudi
5	Southern tropical Euphorbia scrub forests (6A/DS2)	Chengalpet, KMTR , Thoothukudi

VEGETATION OF HILLS AND MOUNTAINS

Dry Deciduous Forests

These forests are found at about 400 m and above. The canopy is closed. Most of the species are deciduous. The undergrowth is usually dense. The common trees are Albizia amara, A.odoratissima, Anogeissus latifolia, Butea monosperma, Chloroxylon switenia, Dalbergia sp. Pterocarpus marsupium, Shorea roxburghii, Strychnos nux-vomica, Terminalia spp., etc. The bamboo, Dendrocalamus strictus is often found. Dodonea viscosa, Securinega virosa, Strobilanthes spp. are some of the shrubs found in these forests. The common climbers are Combretum albidum, Hiptage benghalensis, Toddalia asiatica and Ventilago madraspatana. Cycas circinalis is occasional. Species of Abutilon, Achyranthes, Aristida, Heracleum, Heteropogon, Themeda, Tribulus etc. constitute the ground layer.Within the dry deciduous forest type, following sub types are known to occupy specific areas in the forest divisions.

Sl No	FOREST SUB TYPE	LOCATION
1	Dry teak forests (5A/C1(b)	Kanniyakumari, KMTR
2	Southern Dry Mixed Deciduous Forests (5A/C3)	Tiruvannamalai, Hosur, Vellore, Chengalpet,Tirupattur, Theni, Kanniyakumari, Sathyamangalam, Erode, KMTR, Trichy,Dindigul, Kodaikanal, Madurai, Sivagangai,Thoothukudi
3	Southern Tropical Riverine forest (5/B1)	Tirupattur, Vellore, Hosur, Salem,Sathyamangalam, Attur
4	Secondary dry deciduous forests (5/2S1)	KMTR
5	Dry savannah forest (5/ DS2)	Nilgiris North, KMTR
6	Southern Dry Deciduous scrub Forests	Tiruvannamalai, Hosur, Chengalpet
7	(5A/DS1)	Tiruppattur, Vellore,Theni, NilgiriNorth
8	Dry Euphorbia scrub forest(5/DS3)	Tiruvannamalai, Tiruppattur
9	Laterite thorn forest (type 5/E7)	Nilgiris North
10	The Phoenix Dry Mixed Deciduous forests (5/E 8a)	Coimbatore

TROPICAL MOIST DECIDUOUS FORESTS

This type lies below the zone of semi evergreen and evergreen forests. The trees reach a height of 30 to 36 m and are deciduous. Bamboos are common. Epiphytes are rare. Bombax ceiba, Dillenia pentagyna, Mitragyna parviflora, Tectona grandis, Terminalia spp.,Vitex spp., and Ziziphus xylopyrus are the common trees. Cycas circinalis is occasional. Helicteres isora, Lantana camara var, aculeata and Ziziphus oenoplia are common shrubs. Common climber is Ipomea spp and the common grass is Imperata sp.

Sl No	Forest sub type	Location
1	Moist teak forest (3B/C1(b)	Kanniyakumari
2	Slightly moist teak forests (3B/C1(e)	Kanniyakumari
3	Southern Moist mixed deciduous forests (3B/C2)	Kanniyakumari, Theni, Gudalur, KMTR,Dindigul, Kodaikanal, Madurai,Mudumalai

Depending upon their distribution and dominant species composition, many sub types of the major forest type is recorded in different divisions.

SUB-TROPICAL BROADLEAVED HILL FORESTS

This type of forest is available in medium elevations between 700 and 1000 m. The important trees include Elaeocar pus ser ratus, Pter osper mum suberifolium, Pterospermum xylocarpum, Diospyros ebenum, Mimusops elengi, Premna tomentosa, Anogeissus latifolia, Celtis philippensis, Strychnos nux-vomica, Macaranga peltata, Alseodaphne semecarpifolia, Ficus microcarpa, Sapindus emarginata, Melia dubia, Syzygium cumini, Memecylon edule etc. Shrubs like Murraya koenigi, Chukrasia tabularis, Claucena dentata, Canthium dicoccum, Pavetta indica, Schleichera oleosa, Measa indica, Pterospermum xylocarpum, Solanum surattense, Achyranthes aspera, Cynoglossum zeylanicum are recorded here.

Sl No	FOREST SUB TYPE	LOCATION
1	Southern sub-tropical broadleaved hill forest (8A)	Hosur
2	Southern sub-tropical hill forests (8A/C1)	KanniyakumarTrichy
3	South Indian Sub-tropical Hill Savannah (Wood land)(8A/DS1)	Kodaikanal
4	Ochlandra reed brakes (8A/E1)	Kanniyakumari, KMTR

TROPICAL SEMI EVERGREEN FORESTS

This type occurs on slopes of hills and mountains usually up to 1000 m. Canopy are of two or three storeys. Epihytic orchids are present. Climbers and canes are common. Top canopy consists of Artocarpus spp., Dalbergia latifolia, Hopea spp. etc. The second storey consists of species of Actinoldaphne, Aglaia, Bischofia, Drypetes and Symplocos. Species of Glycosmis, Ixora, Lasianthus, Leea, Memecylon, Pavetta, etc. form the shrub vegetation. The common climbers are Butea parviflora, Cynanchum tunicatum, Entada pursaetha and species of Calycopteris, Dioscorea, Strychnos, Bambusa arundinacea and Ochlandra travancorica are also common.

Sl No	FOREST SUB TYPE	LOCATION
1	West coast semi-evergreen forests (2A/C2)	Kanniyakumari, Theni, Coimbatore, Sathyamangalam,Gudalur, Mudumalai, Kodaikanal

TROPICAL WET EVERGREEN FORESTS

This type is found up to an altitude of nearly 1500 m on the slopes of hills and mountains that receive heavy rainfall. It is primarily met within Anamalai, Kanniyakumari and Tirunelveli hills. Epiphytic orchids, aroids, ferns, mosses and lichens are common. Climbers are conspicuous, spreading over tree canopies. The ground vegetation is generally absent.

Species of Calamus, Pandanus and Palms are found near water courses. Grasses are generally absent. The top canopy is formed by Hopea sp., Aglaia eleagnoidea, Atrocarpus spp., Calophyllum spp., Canarium strictum, Cullenia exarillata, etc. The trees of the second storey include Actinodaphne malabarica, Cinnamomum verum, Dispyros bourdillonii, etc. The common shrubs are species of Ixora, Nothopegia, Pavetta and Strobilanthes sp.

Sl No	FOREST SUB TYPE	LOCATION
1	Southern Hilltop Evergreen Forests (1A/C3)	Kodayar, Nilgiris, Kodaikanal
2	The West Coast Tropical evergreen forests (1A/C4)	Coimbatore, Gudalur, Kodaikanal

MONTANE WET TEMPERATE FORESTS(SHOLAS) & GRASSLANDS GRASSLANDS ARE DIVIDED INTO TWO CATEGORIES.

The montane forest mostly confined to moist and sheltered valleys, glens and hollows as in the Anamalais, Nilgiri and Palanis at above 1000 m. They are known in Tamil as ‘sholas’. The trees are evergreen and usually short boled. Ilex denticulata, I.wigtiana, Michelia nilagrica, Syzygium spp, Vaccinium leschenaultii, V.neilgherrense and Viburnum punctatum are the common trees. Eurya nitida, Rhododendron nilagiricum, Rhodomyrtus tomentosa, Ternstromia japonica are found on the fringes of sholas. Shola forest is considered as the climatic climax type by many workers.

LOW LEVEL GRASSLANDS

These are found up to 1000 m and are very scattered and intermixed with local forest. They are exposed to considerable biotic interference. The dominant species are Arundinella ciliata, A.mesophylla, Chrysopogon orientalis, C. zeylanicus, Cymbopogon coloratus, C. flexuosus, Digitaria ciliaris, Ergrostis tenuifolia, Eulalia trispicata, Ischaemum timorense and Themeda cymbaria. The common trees found scattered among these grasses are Mundulea sericea, Phoenix humilis var. pedunculata and Terminalia chebula

INLAND SANDY HABITAT

SALT MARSH HABITAT

MANGROVE HABITAT

HIGH LEVEL GRASSLANDS

Grasses, herbs and shrubs are found mixed up in varying proportions in this type of vegetation; it covers large areas on the mountain slopes. Agrostis peninsularis, Arundinella purpurea, Avaginata, Bromus ramosus, Chrysopogon zeylanicus, Dicanthium polyptycum, Indochola oligantha, Isachne bourneorum and Tripogon bromoides are the common grasses. Fire resistant fern Pteridium aquilinum is one of the aggressive ferns found in grasslands. In many places, high level grasslands lie in close juxtaposition with sholas. Following sub types are recognized.

Sl No	FOREST SUB TYPE	LOCATION
1	Southern montane wet temperate forests (11A/C1)	KMTR, Nilgiris, Kodaikanal.,
2	Southern montane wet scrub (11A/DS1)	Anamalais
3	Southern montane wet grass land (11A/DS2)

RIPARIAN VEGETATION

This type of vegetation is found along courses of rivers and streams in plains, where alluvial soil is deposited. It forms a very narrow belt along the banks. Sometimes it may extend to higher elevations. The trees may be evergreen or deciduous depending upon the region. Some of the characteristic species include Azadirachta indica, Tamaridus indica, Albizzia amara, A. lebbeck, Acacia ferrugenia, Terminalia chebula, Gyrocarpus americanus, Morinda tinctoria, Ficus bengalensis, Semecarpus anacardium, Terminalia arjuna, Typha angustata and Vitex leucoxylon are some of the plants in this region.

Sl No	FOREST SUB TYPE	LOCATION
1	Tropical Hill Valley Swamp forests(4C/FS2)	Gudalur
2	Tropical Riparian Fringing Forests( 4E/RS1)	Kodaikanal, Dindigul, Mudumalai, KMTR

AQUATIC AND SEMI AQUATIC VEGETATION

Aquatic and semi aquatic vegetation is met within lakes, ponds, puddles, marshy places, etc. Aponogeton nutans, Ceratophyllum demersum, Eicchorina crassipes, Hydrilla verticillata are commonly found. Hydrobryum olivaceum, Polypleurum spp and Willisia selaginoides are found on rocks in rivers. Aeschynomene aspera, Bacopa monnieri, Eclipta prostrata, Hygrophila angustifolia, Rotula aquatica and Typha angustata are found along the margins of lakes, ponds etc. Azolla pinnata, Ceratopteris thalictroides, Isoetes coromandeliana and Marsilea minuta are some of the aquatic pteridophytes commonly met with. (https://www.forests.tn.gov.in/)

TAMIL NADU – BIODIVERSITY

THE FLORA OF THE NILGIRIS AND PULNEY HILL TOPS