Chapter 5: Forest Biota
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CHAPTER 5: FOREST BIOTA 5.1Flora 5.1.1 Habitat Profile Large tracts of Koyna WLS comprise natural habitats including forests, perennial and seasonal wetlands, hill-capped plateaux and grasslands. However, some parts of the buffer zone of the protected area are modified for agricultural purposes, habitations, access routes, tourism and its related ancillary facilities and windfarms. (Plates 5-1). 5.1.1.1 Forest Types According to the Champion and Seth revised Classification of Indian Forests (1968) the vegetation of Koyna WLS represents the following different forest-types (Figure 5-1 and Figure 5-2.). Type 1A/C4 (Group 1 – Tropical Wet Evergreen Forests, Sub-group A – Southern Tropical Wet Evergreen Forests, Sub-type C4 – West Coast Tropical Evergreen Forests) These forests occur throughout the tropical portion of the country and more extensively along the Western Ghats. They are associated with rainfall more than 2000 mm, altitude ranging between 800-1500 m. These forests are lofty, dense and characterised by the large number of species of trees that occur together. The crown canopy is 70-80 %, epiphytes are numerous mainly ferns, mosses and orchids and cauliflory is evident. In the top storey, trees with long cylindrical boles usually with smooth bark are typical and a few of them are buttressed. Leaves are usually thick, coriaceous and glossy. Grasses are absent, regeneration of dominant species is frequent and the forest floors are covered with thick layer of leaf litter. (Plate 5-2). In Koyna WLS, evergreen forests are fragmented and occur in discrete patches, generally in the vicinity of perennial streams. This type of forests are distributed in areas such as Kala Mura in Karanjwade, on way to Vasota Fort, Dicholi, Shirshingi and Jungati beats, Panchdhara, Ramban and Navja. 1 The tall components in these forests are Canarium strictum, Holigarna grahmii, Myristica dactyloides, Persea macrantha, Chrysophyllum roxburghii, Lophopetalum wightianum, Dysoxylum gotadhora, Beilschmiedia dalzellii, Mangifera indica, Drypetes venusta, etc. The understorey mainly comprise of Aglaia lawii, Aglaia elaeagnoidea, Nothopegia castanaefolia, Flacourtia montana, Turpinia malabarica, Harpullia arborea, Mimusops elengi, Cinnamomum spp., Litsea spp., Eugenia gardneri, Dimorphocalyx glabellus var. lawianus, Psydrax umbellata . Smaller trees in these forests are Agrostistachys indica, Meiogyne pannosa, Diospyros montana, Cleidion spiciflorum, Ancistrocladus heyneanus etc. Shrubby components are comprised of Psychotria truncata, Ixora pavetta, Mallotus philippensis, Lasianthus acuminatus, etc. In riparian areas in such forests, gregarious thickets of Pandanus odorifer are evident. A few woody climbers in such forests are Gnetum ula, Embelia drupacea, Entada rheedei, Chonemorpha fragrans, Ancistrocladus heyneanus, Luvunga eleutherandra, Paramignya monophylla and Toddalia asiatica. Undergrowth is formed by Glycosmis pentaphylla, Strobilanthes heyneanus, Dracaena terniflora and a few species belonging to Cyperaceae and Asteraceae families. Epiphytic plants in evergreen forests are restricted to family Orchidaceae belonging to the genera like Aerides, Bulbophyllum, Eria and Vanda and Apocynaceae Hoya wightii. Type 2A/C2 (Group 2 – Tropical Semi-evergreen Forests, Sub-group A – Southern Tropical Semi-evergreen Forests, Sub-type C2 – West Coast Semi- evergreen Forests) This type of forests is intermediate between the tropical evergreen and moist deciduous forms and usually includes groups that are fairly typical of both. The type occurs throughout the moister parts of southern tropical region and is always occur in association with true evergreen forests. This type forms closed high forests consisting big dimension trees. In such forests, many of the emergent trees are deciduous whereas the canopy and understorey are composed of evergreen species. Buttressed stems are quite frequent and occur in both evergreen and deciduous species. Bark of 2 trees tends to be rougher and cauliflory rarer. Presence of Xylia xylocarpa is evident in these forests. The general canopy and undergrowth as well is copious but less dense than evergreen forests; climbers tend to be very heavy and epiphytes are abundant including ferns and orchids. (Plate 5-3). In Koyna WLS, semi-evergreen forests are dominant and forms large contiguous patches along hill slopes throughout the sanctuary. This type of forest is well represented in the areas like Ozarde, Navja, Takvali, Shirshingi, Dicholi, Karanjwade, Maldev and Metindavali. Top canopy layer in these forests comprises of species like Dimocarpus longan, Memecylon umbellatum, Terminalia bellerica, Garcinia talbotii, Garcinia indica, Carallia brachiata, Prunus ceylanica, Ficus nervosa, Chionanthus mala- elengi, Syzygium cumini, Mangifera indica, Olea dioica, Sageraea laurifolia, Litsea josephii, Xylia xylocarpa, Sterculia guttata, Chukrasia tabularis, Elaeocarpus serratus, Diospyros sylvatica, etc. The second storey in this type is dominated by Actinodaphne gullavara, Cinnamomum spp., Litsea josephii, Nothopodytes nimmoniana, Euonymus indicus, Glochidion ellipticum, etc. The shrub species in undergrowth consists of Allophylus cobbe, Crotalaria retusa, Canthium angustifolium, Maytenus rothiana, Premna coriacea, Mallotus resinosus, Pavetta siphonantha, Symplocos racemosa. Herbaceous species typical to this type are Strobilanthes heyneana, Ophiorrhiza rugosa var. prostrata, Gymnostachyum glabrum, Rubia cordifolia, Justicia terminalis, Piper trichostachyon. A grass species Cyrtococcum oxyphyllum and ground orchids such as Cheirostylis parvifolia and Peristylus aristatus are evident and typical to the type in the sanctuary. Dominant woody climbers are Eleagnus conferta, Moullava spicata, Oxyceros rugulosus, Embelia ribes, Caesalpinia cucullata, Mucuna monosperma, Combretum albidum, etc. An epiphytic flora of these forests includes orchids such as Oberonia recurva, Oberonia brunoniana, Smithsonia viridiflora, Aerides maculosa, Dendrobium macrostachyum, Dendrobium microbulbon, etc. 3 Type 2B/E4 (Group 2 – Tropical Semi-evergreen Forests, Sub-group B – Northern Tropical Semi-evergreen Forests, Edaphic type – Lateritic Semi- evergreen Forests) An edaphic sub type of tropical semi-evergreen forests associated with lateritic soils in Peninsular India is found typically distributed along the margins of lateritic plateaux in the sanctuary. These forests exhibit a few common features as they consists some of the species that are evident in subtype 2A. However, these forests differ in overall formation that of the high semi-evergreen type by smaller size of trees and a presence of few characteristic species. Tree species associated with this type includes Memecylon umbellatum, Syzygium spp., Alseodaphne semecarpifolia, Hymenodictyon obovatum, Mallotus philippensis, Ficus racemosa, Ficus arnottiana, Celtis tetrandra, Atalantia racemosa, etc. Common shrub species includes Rauvolfia verticillata, Bridelia stipularis, Flueggea virosa, Ziziphus rugosa, Capparis moonii, Leea setuligera, Grewia spp., Woodfordia fruticosa, Gnidia glauca, etc. Climbers typical to these forests are Anodendron paniculatum, Carissa inermis, Arnicratea grahamii, Dioscorea spp., Combretum spp., etc. Epiphytes and parasites are much dominant in this type than that of the other. Some common epiphytic species are Dendrobium aqueum, Helixanthera hookeriana, Helicanthes elastica, Conchidium spp., Hoya wightii, etc. Type 3B/C2 (Group 3 – Tropical Moist Deciduous Forests, Sub-group B – South Indian Moist Deciduous Forests, Sub- type C2– Southern Moist Mixed Deciduous Forests) This type of forests is common and distributed throughout the country. Within Koyna sanctuary, these forests are confined in low altitude areas where rainfall is comparatively low. This type is well distributed in the northern parts of the sanctuary including Kusapur, Khirkhindi, Uchat, Arav, Akalpe, Shindi, Valvan, Pimpri and on the outskirts of Navja, Ghatmatha, Avasari, Pali, Deur and Vele in the southeast. (Plate 5-4). The common tree species associated to this type of forest are Terminalia paniculata, Terminalia chebula, Terminalia tomentosa, Syzygium spp., Macaranga peltata, Dillenia pentagyna, Bombax spp., Bridelia retusa, Careya arborea, Anogeissus latifolia, Xantolis tomentosa, Lagerstroemia microcarpa, etc. 4 Shrubs such as Catunaregum spinosa, Meyna laxiflora, Murraya koenigii, Glochidion ellipticum, Allophyllus cobbe, Scutia myrtina, Carissa congesta, Grewia spp. etc. Undergrowth in this forest type is dominated by thick mat of Strobilanthes callosa and open slopes are covered by Gnidia glauca, Holarrhena pubescens, Ixora brachiata, Woodfordia fruticosa, Scutia myrtina, etc. Climbers and stranglers such as Cissus spp., Smilax ovalifolium, Moullava spicata, Hemidesmus indicum, Calycopteris floribunda, Derris spp., Dalbergia spp., etc. 5.1.1.2 Lateritic Plateaus Lateritic plateaus are a distinct geographical feature of Northern Western Ghats of India (Lekhak & Yadav, 2012). Plateaus are specialized habitats that support a unique variety of ephemeral and annual herbaceous flora. Factors such as high extent of species diversity and richness, range of adaptations in species, high percentage of endemism have always been topics of interest for botanists and ecologists. However, rocky plateaus along northern Western Ghats were remained unexplored for long time. Chavan et al. (1973) have enumerated 128 species from Kas area including forests, slopes and cliffs around Kas ferricretes. Porembski et