Types of Forest
(I)Semi-Evergreen Forests
Semi-evergreen forests (west coast semi-evergreen forests) are generally considered as a transitional stage between evergreen and moist deciduous forests. It is also found in localities where the evergreen forests are subjected to high disturbances. These forests occur between 600 to 800 m and in some places it extends up to 900 m. Animal species such as lion tailed macaque, Nilgiri langur, Nilgiri marten, small Travancore flying squirrel, brown mongoose, Malabar civet, and many birds such as the great Indian hornbill and the Bourdillon's great eared night jar occupy specific niches in these forests.
The floristic composition is an admixture of both evergreen and deciduous species in the top storey. The prominent evergreen species are Artocarpus heterophyllus, Bischofia javanica, Calophyllum elatum, Euvodia lunuankenda, Hopea ponga, Mangifera indica, Mesua ferrea and Myristica dactyloides. The deciduous floral elements include Acrocarpus fraxinifolius, Bombax ceiba, Chukrasia tabularis, Dalbergia latifolia, Grewia tiliaefolia, Lagerstroemia microcarpa, Pterospermum sp., Terminalia bellirica and Toona ciliata. The species occurring in the lower layer are the same as seen in the evergreen forests.
(i)Southern Hill Top Tropical Evergreen Forest: It is an inferior variety of the typical evergreen forest, reaching to a maximum height of only 10 m.
Distribution:This type of forest abounds in the Andamans and Western Ghats. They are usually seen on the slopes and tops of hills.
Locality factors: High winds, less favourable soil and climatic conditions restrict the formation of a climax. Rainfall is usually high, over 4500 mm and humidity is high even during periods of scanty rainfall.
Floristic: Top canopy trees & Second storey trees - Artocarpus heterophyllus, Canarium strictum, Cedrela toona, Cullenia exarillata, Dysoxylum malabaricum, Elaeocarpus seratus, Eugenia species, Holigarna beddomei, Mesua ferrea.
Bamboos : Ochlandra travancorica
Shrubs: Pandanus spp, Strobilanthes spp
Climbers: Calamus spp
(ii)West Coast Tropical Evergreen Forest: These are dense evergreen forests with lofty trees of 45 m or more height. A large number of species occur mixed together. This makes the canopy extremely dense. Ferns, mosses, aroids and orchids are seen in plenty. The undergrowth consists of cane, creeping bamboo, and palms. With the increase in elevation and rainfall, the height of the forest diminishes, though it remains dense and evergreen, changing into the stunted wet sub-tropical forest.
Distribution: Enjoys a wide distribution over the Western Ghats
Locality Factors: It is seen in an altitudinal range of about 250-1200 m.The rainfall varies from 1500-5000mm.
Floristic: These forests are characteristic in having a high proportion of Mesua ferrea, Palaquium ellipticum, Cullenia exarillata and Calophyllum elatum. The absence of Hopea parviflora and Dipterocarpus indicus needs mention.
Top Canopy Trees: Artocarpus hirsutus, Bischofia javarnica, Canarium strictum, Calophyllum elatum, and Dysoxylum malabaricum
Second Storey Trees: Actinodaphne hookeri, Cinnamomum zeylanicum, Euphoria longana, Myristica beddomei, Vateria indica.
Shrubs: Leea indica, Pandanus spp, Strobilanthes spp, Rubiaceae. No grass in undistributed forest.
Climbers: Climbers on the whole are not woody
(iii)Wet Evergreen and Semi-evergreen Climax Forests: In Kerala, wet evergreen forests are mostly confined to the windward side of the WG, where the rainfall is above 2000mm. By taking into account the distribution pattern of certain characteristic species, which reflect the climatic variations, the forests are further subdivided into eight main floristic types and three facies. All these types are classified according to low (0-800m), medium (800-1450m) and high (1400-1800m). The medium elevation forests in some places may appear at lower elevation (650 m) due to local variations in the moisture and exposure.
Based on the moisture regime, moist deciduous forests are divided into primary/climax or secondary moist deciduous forests. The primary moist deciduous forests generally occupy the rainfall zone of 1500 to 1800 mm, as a transition between wet evergreen and dry deciduous forests. The secondary moist deciduous forests occur within the potential area of wet evergreen formations, where the rainfall is more than 2000 mm. Although the floristic composition is almost similar in both the types, the relative dominance of certain species varies.
(i)Secondary Dry Deciduous Forests: These are inferior climax forests predominated by poorly shaped, small sized trees. Sandal is also seen in such forests.
Distribution: They are seen distributed in dry deciduous forests and intruding into the drier parts of moist deciduous forests.
Locality Factors: The soil surface is hard and impervious due to exposure and trampling effected by heavy grazing, fuel and timber collection.
Floristic: Top canopy trees-Bombax ceiba, Grewia tiliaefolia, Schleichera oleosa, Tectona grandis
Second Storey:Feronia limonia, Santalum album
Shrubs:Dodonaea viscosa, Lantana camara
(ii)Southern Dry Deciduous Forests: The sub group differs from the dry teak forest species-wise, though typical plants like Boswellia are conspicuous. Heavy grazing invigorates growth of thorny species. Bamboo is mostly absent and of poor quality, if present. Climbers are rarely seen.
Distribution: It occurs throughout peninsular India, especially in drier localities.
Locality factors: The rainfall varies from 875 mm –1125mm on dry sites and soils. The shallow soiled, well-drained hillsides and the undulating grounds have identical forests, making it difficult to establish the relation of site and climate to the forest insitu.
Floristic: Diospyros tomentosa, Chloroxylon swietenia, Hardwickia binata, Boswellia serrata
(iii)Primary Moist Deciduous Forests: Primary deciduous forests are found in isolated patches between the Anamalai and Wayanad plateaus. Denser part of this type is the form of woodland and savanna woodland. Dillenia pentagyna and Tabernaemontana heyneana are characteristic species of this type. Lagerstroemia microcarpa and Tectona grandis, together with other species such as Anogeissus latifolia, Dalbergia paniculata, Pterocarpus marsupium, Terminalia paniculata, Hymenodictyon excelsum, Haldina cordifolia are common.
(iv)Secondary Moist Deciduous Forests: In Kerala secondary forests cover larger areas than the primary type, mostly in the form of dense forests and woodland to savanna woodland. Especially on the steep slopes, they are found as tree savanna. Floristically, there are similar to primary moist deciduous however, some deciduous species like Dillenia pentagyna, Tabernaemontana heyneana, Strychnos nux-vomica, and Xylia xylocarpa, are relatively more common than in the primary forests. Tectona grandis, which is extensively planted, has also been found mixed with other species in dense formations. In the dense forests often there is dominance of evergreen species like Ixora brachiata, Olea dioica, Persea macrantha, Dimocarpus longan, Flacourtia montana etc.
(v)Dry Deciduous Forests: Within the given rainfall regime, dry deciduous forests in Kerala State are rare. They are confined to northern slope of Anamalai in Chinnar Wild life Sanctuary, eastern part of Mannarkad Division, and South Wayanad Wildlife Sanctuary where the rainfall is less than 1200 mm. The physiognomic structure of these dry deciduous forests is highly variable, due to impoverishment of soil, especially on steep slopes, and also due to anthropogenic pressures including fire and grazing. Three types of dry deciduous forests have been recognized.
(a)Albizia amara –Acacia spp. Gyrocarpus asiaticus type (AAG)
This type is found only in Chinnar Wild life Sanctuary, up to 650 m. On the lower slopes, Acacia chundra and A.leucophloea are characteristic species, particularly in the scrub woodland and thickets. Albizia amara, Erythroxylum monogynum, Dichrostachys cinerea and Chloroxylon swietenia, and Hardwickia binata are the other common species of this type.On the slopes, especially on skeletal soils, tree savannas are the prominent formations. In such habitat Gyrocarpus asiaticus, with metallic-coloured bark, is the characteristic species, along with other slope-loving species, like Cochlospermum religiosum, Givotia rottleriformis, Sterculia urens and Commiphora caudate.
(b)Anogeissus latifolia – Pterocarpus marsupium – Terminalia spp. type (APT)
This type is found above 600 m in Mannarkad Division (northern part) and Chinnar WLS. As it is generally found on slopes, physiognomy varies from savanna woodland to tree savanna. Apart from the species mentioned in this type Dalbergia paniculata, D.latifolia, Emblica officinalis, Kydia calycina and Grewia tiliifolia are also common.
(c)Anogeissus latifolia – Tectona grandis – Terminalia spp.type (ATT)
This type is found only in the South Wayanad WLS. It is generally represented by dense forest and woodland to savanna woodland. Compared to adjacent primary moist deciduous forests, here the species like Dillenia pentagyna, Alstonia scholaris, Callicarpa tomentosa disappear and the species mentioned in the type become dominant. Other common species include Diospyros melanoxylon, Madhuca latifolia, Emblica officinalis, Lagerstroemia parviflora Careya arborea etc. In some poorly drained low-lying areas Shorea roxburghii become conspicuous.
The term 'Shola' owes its origin to the Tamil word 'Cholai' meaning a stream or a cool, shady place. Gradually, 'Cholai' transformed to 'Shola', through the intermediary form 'Sholai', and began to be used to refer to both 'streamlets' and 'forests associated with the streamlets'. Scientifically speaking, 'Sholas' are Tropical Montane Forests' situated in the higher mountain tracts of Western Chats, above 1500 m, interspersed with rolling grasslands (Southern Montane Wet Grasslands). They are the continuation of the 'West Coast Tropical Wet Evergreen Forests' in the higher altitudes. Shola forests have high ecological significance in protecting the head waters of rivers. They have the capability of holding up of water received by precipitation like a sponge and thus preventing rapid run off. The vegetation is also very characteristic. The trees are stunted with an umbrella shaped canopy. The branches are crooked and densely covered with epiphytic mosses, ferns lichens and orchids.
The species are basically of a tropical stock. But, fire resistant temperate species dominate the forest ecotones which act as a natural fire belt. Woody species in the open grasslands are cold resistant and have a wider geographical range extending to the higher altitudes in the Himalayas or other temperate regions. However, as majority of species are of tropical stock, they cannot withstand the low temperature in an open eco-climate, and are consequently eliminated.
The situation is worse in the eastern and southern slopes which are more prone to the effects of morning sun. So, Sholas in these regions are comparatively small, the trees are more stunted and crooked, their leaves being more coriaceous and re-curved. Frost, fire and wind are the three main factors determining the distribution of the sholas. The principal tree species are Neolitswa zeylanica, N. scrobiculata, Cinnamomum wightii, Actinodaphne bourdillonii, Litsea wightiana, L. ligustrina, Elaeocarpus serratus, Ilex denticulata, I. wightiana, Rapaenea thwaitesii, R. wightiana, Ligustrum perrottetii, Michelia nilagirica, Microtropis ramiflora, Glochidion neilgherrense, Syzygium densiflorum, S. arnottianum, Symplocos perndula, Schefflera racemosa etc. Species such as Ilex wightiana, Gordonia obtusa, Fagraea ceylanica, Schefflera racemosa, Prunus ceylanica and 'Tree ferns' such as Cythea crinita, C. nilgirensis etc have more affinity to water and are found along the streams. In the shola fringes, trees such as Rhododendron nilagiricum, Vaccinium leschenaultii, Lasiosiphon eriocephalus, Elaeocarpus recurvatus, Photinia notoniana, Eurya nitida, Symplocos larina, Ternstroemia japonica, Daphniphyllum neilgherrense etc.
Shrubs and herbs found here are Rhodomyrtus tomentosa, Hypericum mysurense, Dodonea viscosa, Berberis tinctoria, Maesa perottetiana, Gaultheria fragrantissima, Euphorbia laeta, Jasminum bignoniaceum, Leucas lanceafolia, Moonia heterophylla etc. In low altitude shola regions, Hydnocarpus alpina, Chionanthes linocieriodes, Mastrixia arborea, Garcinia cowa, Elaeocarpus munronii, E. tuberulatus, Acronychia laurifolia, Beilschmedia wightii, Bhesa indica, Bischofia javanica, Isonandra candolleana, Gomphandra coriaceae, Syzygium cuminii, Persea macrantha etc. dominate. The major undergrowths here are Ladianthus acuminatus and Ardisia rhomboidea, in addition to different species of Strobilanthes.
Strobilanthes which is the major undergrowth inside the sholas shows habitat perference in accordance with the availability of light. S. homotropa, which is the dominant undergrowth, is found under the dense canopy, whereas S. micranthes and S. luridus, the other two dominant species, prefer more exposed regions, such as shola margins. The famous 'Neela-kkurinji' S. kunithianus is found only in fully exposed regions, such as grasslands.
As the extent of sholas is so small and as they occupy very inaccessible mountain tops, having a very hostile climate, there are still some regions, which remain unexplored. These shrinking ecosystems abode a lot of rare, endangered and endemic species, many of which face danger of extinction.
In Kerala grasslands are generally found above 1500 m. The grasslands, which are also called as ‘shrub-savanna’ are characterised by herbaceous and shrubby species mixed with grasses.
The grasslands below 1800 m that are adjacecnt to medium or high elevation evergreen forests, are often found with sparse trees, represented by Wendlandia thrysoidea, Glochidion spp. Terminalia chebula, Emblica officinalis, Careya arborea, Briedelia crenulata; in some places a dwarf palm. Phoenix is found in patches. At this elevation range, grasses are tall, and reach the height up to 1.5 m. They are commonly represented by Androprogon lividus, Arundinella purpurea, Agrostis peninsularis, Chrysopogon zeylanicus, Eulalia phaeothrix, Sehima nervosum, Heteropogon contortus, Eulalia sp, Themeda sp, Ischaemum indicum, and Tripogon bromoides. In cattle grazed and frequently burnt areas, unpalatable Cymbopogon flexuous and Pteridium, a fern are frequent. The grasses in this zone are mixed with other herbs like Crotalaria, Desmodium, Hypericum, Knoxia, Leucas, Lobelia, Osbeckia etc. Phlebophyllum kunthianum, a monocarpic shrub species, often dominates the grass land landscape.
At above 1800 m, especially in the Anamalai region (Eravikulam and Munnar) grasslands are more specialised. During the colder months, the minimum temperature often goes below zero degree centigrade. In this zone grass layer is less than 1m and is represented by Andropogon foulkesii, Anthistiria ciliata, Arundinella spp., Arundinaria villosa, Bothriochloa pertusa, Chrysopogon orientalis, Cymbopogon spp.,Eragrostis nigra, Eulalia spp., Heteropogon contortus , Isachne spp., Themeda spp., Tripogon bromoides and Zenkeria elegans.
Among Shrubby elements Berberis tinctoria, Gaultheria frangrantissima, Hypericum mysorense, Lobelia excelsa, Oldenlandia stylosa, Osbeckia wightianum, Pteridium aquiilnum, Rubus fairholmianus, Phlebophyllum kunthianus are particularly frequent. Rhododendron arboreum var. nilagiricum in the form of small tree is also sporadically seen in grasslands.
The common herbaceous elements among grasses include Anaphalis spp., Campanula fulgens, Cassia spp., Crotalaria notonii, Cyanotis spp.,Indigofera pedicellata, Justicia simplex,Knoxia mollis, Leucas suffruticosa, Lilium neilgherrense, Oldenlandia articularis Polygala sibirica, Striga asiatica, Viola patrinii,and Wahlenbergia gracilis. In the swampy pockets Commelina spp., Centella asiatica, Drosera peltata, Fimbristylis uliginosa etc are common. .
Mangroves are wetland ecosystems formed by the assemblage of specialized plants and animals adapted to semi saline swamps along coasts. Mangrove forests of Kerala are highly localized, but the species diversity of these mangroves and its associates are comparatively rich. It is confined to the upper reaches of estuaries, lagoons, backwaters and creeks. In Kerala mangroves are distributed in all the districts except Idukki, Pathanamthitta, Palakkad and Wayanad. Maximum extent is reported from Kannur district. The total extent of mangrove forests in the state is estimated to be less than 50km2 (Mohanan 1997) . Mangroves play an important role in the economy of coastal people through various ways. Mangroves provide excellent habitat for migratory birds, serve as breeding ground for many species of fishes and prawns helps in controlling pollution, rutting of husks etc.The important mangrove plants are
Acanthus cillicifolius, Acrostichum aurem, Aegiceras corniculatum, Avicennia officinalis, A, rina, Azima tetracantha, Bruguiera gymnorrhiza, B. cylindrica, B sexangula, Excoecaria agallocha, E indica, Kandelia candel, Rhizophora apiculate, R mucronata, Sonneratia caseolaris, Calophyllum etc. Some of these species that disappeared from the Kerala coast are Azima tetracantha, Ceriops tagal, Heritiera littoralis and Flagellaria indica have discourteous distribution. Calamus rotang and Syzygium travancoricum are some of the rare and endangered species found in the mangroves.
The major threats to the mangrove forests are land reclamation for urbanization, intensive aquaculture felling of mangrove trees for fuel and fodder, unsustainable land use, ambiguity in ownership etc.
High Elevation Type: The high elevation forests are generally confined to altitude between 1400 and 1800 m, where the mean temperature of the coldest month varies 14-16ºC and length of the dry period ranges from 2 to 3 months. Rainfall in the area varies between 3000 to 5000 mm. structurally, the forests are stunted, with two ensembles, and canopy seldom exceeds 15 m. Two floristic types have been identified in these high elevation forests.
Bhesa indica – Gomphandra coriacea -Litea spp. type (BGL)
In the Western Ghats of Kerala , this type is found between the Ariyankavu Pass and Palghat gap, between 1400 and 1800 m. At this elevation range, several species of the lower elevations disappear or become very rare viz Cullenia exarillata, Palaquim ellipticum, Diospyros spp and Agrostistachys meeboldii. The family Annonaceae which is dominant at lower strata in both low and medium elevations, disappears completely at high elevation. However, some species that are less important at lower elevations become significant at higher elevation range. Gomphandra coriacea,Gomphandra tetrandra of low elevation forest, become conspicuous at lower strata. Lauraceae, which tends to become common with the increase of elevation, manifest its highest diversity. Several other species like Schefflera capitata, Mastixia arborea, Archidendron clyparia, Hydnocarpus alpina, Cocculus laurifolius, Acronychia pedunculata, Isonandra spp. Meliosma spp., Symplocos spp are also common in this type.
Schefflera spp. Meliosma arnottiana -Gordonia obtuse type (SMG)
This type found in north of the Palaghat gap (between 1400 and 1800 m) as a transition between CMP of medium elevation and LSM of montane type. Compare to its counterpart (BGL) type in the south of the Palaghat gap, SMG type requires 3 to 6 months dry period.
Even though the species mentioned in this type is found throughout the medium elevation and above, they reach their optimum presence in the above mentioned region. Among Araliaceae, Schefflera capitata, S. micrantha, S.racemosa. S.wallichiana are common. Lauraceae (Litsea, Cinnamomum, Alseodaphne, Neolitsea) and Myrtaceae (Eugenia, Syzygium, Rhodomyrtus) become conscpious from this type and towards montane type.
Low Elevation Types: The low elevation types are typically ‘Dipterocarp’ Forests. Structurally, they are all dense forests with four structural ensembles (sense Oldeman, 1974) and an emergent layer. Canopy height often reaches 35-45 m.
Dipterocarpus indicus: – Kingiodendron pinnatum – Strombosia ceylanica type (DKS)
This type is confined to south of the Ariankavu Pass (8º 20’N to 9º 00’N), where the length of the dry season varies from 2 to 3 months. Like in the other two low elevation evergreen forest types, Dipterocarpus indicus is a characteristic canopy species. Kingiodendron pinnatum, yet another important canopy tree in the type, shows a peculiar distribution pattern. It is very rare in the low elevation wet evergreen type between the Ariyankavu Pass and the Palaghat Gap, however, becomes prominent again north of the Palaghat Gap. Strombosia ceylanica has a wide distribution throughout the WG, but is more common among the canopy trees of low elevation types, south of the Palaghat Gap.
The denser part of the DKS type is represented by two facies, which are found above 8 º 40’N. Below, that, the DKS type is mostly in the form of fragments or in a degraded condition. Some of the big fragements are close to climax forests with the presence of Vateria indica, Kingiodendron pinnatum, Hopea parviflora, Mesua ferrea, and Strombosia ceylanica. Dipterocarpus indicus are rare in these fragments.
The two facies that have been identified under DKS type, one is characterized by the local abundance of otherwise two geographically rare species (Hopea racophloea and Humboldtia decurrens ),and the other corresponds to a particular ecosystem adapted to water logged areas.
Hopea racophloea – Humboldtia decurrens facies
This facies is confined to humid valleys between Kallar and Shendurni Rivers , west of Agastya malai. Although, the distribution of Hopea racophloea and Humboldtia decurrens goes beyond the Ariankavu Pass, their presence in DKS type is more conscipious than in any other regions. Hopea racophloea with exfoliating bark is a canopy tree. Its regeneration is always gregarious. Humboldtia decurrens, a caulifliorus tree with large winged pinnate leaves, is prominent in the third structural ensemble of the forest. Other common canopy trees are Vateria indica, Artocarpus gomezianus, Otonephelium stipulaceum, Holigarna nigra, Cynometra sp. Fficus beddomei and Poeciloneuron indicum has been found in patches. Semecarpus auriculata and semecarpus travancorica are common towards the lower limit of the type. Among the species of lower ensembles Diospyros paniculata, Fahrenheitia zeylanica, Diospyros humilis, Hydnocarpus macrocarpa, Knema attenuata, Cynometra bedlomei are important.
Medium Elevation Types: Medium elevation forests are structurally very similar to low elevation ones especially at the lower limits, they are tall (canopy 35-45 m) with four structural ensembles. Towards the upper limit, the forests are stunted with two or three ensembles (canopy < 18 m ). They differ floristically from low elevation types due to disappearance of species like Dipterocarpus spp., Kingiodendron pinnatum etc. At this elevation range, the relative abundance of certain species like Strombosia ceylanica, Vateria indica, Diospyros bourdillonii etc. have also become less. Two main types and one facies have been recognized at medium elevation.
Myristica Swamp Forest: They are fairly dense evergreen forests reaching a height of 15-30m, with clean slender boles. The undergrowth includes mainly aroids and scitaminae.
Distribution: Restricted to valleys in the tropical evergreen forest of Travancore
Locality Factors: It occurs as fringe forest on slow moving streams. The soil is sandy alluvium with high humus content.The soil layer remains inundated from June to January.
Floristic: Top canopy trees & second storey trees- Myristica magnifica, Myristica malabarica, Lagerstroemia speciosa, Laphopetalum wightianum, Carallia brachiata
Shrubs:Pandanus sp
IV a – Cyperaceae, Scitaminae
Climbers – Calamus sp
Nilgiri Sub-tropical Hill Forests: These forests resemble the tropical rain forest except for the stunted growth of trees. They are less luxuriant and the trees have shapeless boles, often festooned with epiphytes. Strobilanthes usually forms dense undergrowth.
Distribution: They are seen in the Nilgiris, Anamalai, and Palani Hills of Tamilnadu and Kerala.
Locality Factors: This sub group occurs at altitudes between 1000m and 1700m on the South Indian hills. The mean annual temperature ranges from 17-22degree Celsius. The rainfall recorded is high and varies from 1500-6600mm. The number of rainy days amounts to a Maximum of 132.
Floristic: Top Canopy trees and second or secondary storey trees-Calophyllum elatum, Actinodaphne hookeri, Canthium dicoccum, Ficus arnottiana, Persia macrantha
Shrubs – Strobilanthes sp
Climbers – Calamus sp
South Indian Sub Tropical Hill Savannah: An open savannah forest with tall, coarse grass reaching a height of 2-3 m. Scattered trees of deciduous nature are also seen.
Distribution: Found in the Nilgiri and Palani Hills of Tamil nadu and Kerala
Locality factors: The rainfall varies from 1500 mm upwards and is evenly distributed.
Floristic: Top canopy trees- Dalbergia latifolia, Anogeissus latifolia.
Second Storey Trees – Olea dioica
Shurbs- Phoenix humilis
Southern Moist Mixed Deciduous Forest: Top Canopy trees and Second storey trees-Terminalia paniculata, Terminalia tomentosa, Careya arborea, Phyllanthus emblica, Dillenia pentagyna, Sterculia villosa, Albizia odoratissima, Cassia fistula, Gmelina arborea, Saccharum spontaneum (Grass species).
Southern Montane Wet Grasslands: They are seen over large areas on the rolling downlands. The highest parts of the forest and the forest in the depressions are subject to annual frost. Fires are frequent and grazing is heavy.
Floristic: Cymbopogon flexnosus, Eragrostis nigra, Themeda cymbaria
Southern Montane Wet Temperate Forest: They are luxuriant evergreen forests with closed canopy. The trees attain considerable girth, but are short baled and branchy. The leaves exhibit a varying range of colours, which is a distinct feature of these forests. The wet nature of the forest results in abundance of moss, ferns and other epiphytes. The canopy differentiation is not discernible.
Distribution & Locality factors: It occurs in Tamilnadu and Kerala on the Nilgiris, Anamalia, Palani and Thirunelveli hills from about 1500 m upwards. It is also found in patches of Shola of the sheltered plains. The mean annual temperature ranges from 14-17 degree Celsius. The mean annual rainfall varies from 1300-6000 mm. The soil is reddish or yellowish clay, topped by varying depths of soil rich in humus.
Floristic: Ternstroemia gymnanthera Syzygium,S.arnottianum,S.tamilnadensus, calophyllifolium, E. arnottiana, E. Montana, Rhododendron nilagiricum, Elaeocarpus spp.
Southern Secondary Moist Mixed Deciduous Forest
Floristic: Top canopy trees-Terminalia paniculata, Mangifera indica, Dalbergia latifolia, Lagerstroemial anceolata, Alstonia scholaris, Xylia xylocarpa.
Second Storey Trees-Olea dioica, Careya arborea, Phyllanthus emblica, Callicarpa tomentose Phylanthus emblica.Bamboo absent.
Shurbs - Clerodendrum viscosum, Helicteres isora, Glycosmis pentaphylla
Climbers – Calycopteris floribunda, Acacia chesia
Tropical Riparian Fringing Forest (Riparian Forest)
The forest type is characterized by a few evergreen and semi-evergreen species restricted on the sides of streams forming a narrow fringe. In the Sanctuary the forest type is restricted mostly along the sides of the Pambar and Chinnar rivers.
The dominant species are Terminalia arjuna, Hopea parviflora, Bischofia javanica, Mangifera indica, Drypetes roxburghii, Vitex leucoxylon, Pongamia pinnata, Garcinia gummi-gutta, Mallotus stenanthus, Calophyllum calaba, Entada rheedei, Lepisanthes tetraphylla, Syzygium cumini, Schefflera racemosa, Homonoia riparia, Vitex altissima, Salix tetrasperma, Gnetum ula etc
Very Moist Teak Forest:In this type, teak forms only 10 percent of the overwood. Most of these forests are sub climaxes in semi evergreen forest and are of secondary orgin.
Floristic: Top Canopy trees – Lagerstroemia lanceolata, Grewia tiliifolia
Second Storey trees – Dillenia pentagyna, Kydia calycina
Bamboos – Bambussa bambos
Shrubs – Clerodendrum viscosum, Glycosmis pentaphylla, Lantana camara
Climbers – Spathalobus roxburghii, Acacia pennata.
West Coast Semi-Evergreen Forest: Being intermediate between the tropical evergreen and moist deciduous forest, these are difficult to define except describing in comparative terms. They usually include patches of both these types mixed into a mosaic. It forms a closed high forest; the dominant trees sometimes will grow very large. Buttressed stems continue to frequent both in evergreen and moist deciduous forests. The general canopy is less dense than in true evergreen and the evergreen undergrowth rather copious; climbers tending to very heavy. Bamboo is usually found well distributed in the evergreen forest. Epiphytes are abundant, including many ferns and orchids.
Locality factors: Rainfall varies from 2000-2500 mm on the plains
Floristic: Top canopy trees-Terminalia tomentosa, Dalbergia latifolia,Haldina cordifolia, Xylia xylocarpa, Artocarpus hirsutus, Hopea parviflora, Mesua lerrea
Second Storey Trees- Hydnocarpus pentandra, Bischofia javanica, Mallotus philippensis, Kydia calycina
Bamboos- Ochlandra sp, Bambusa bambos