Biogeographical Classification of India PDF

## Biogeographical Classification of India The biological area of India has been divided into 9 biogeographical regions on the basis of ecosystem diversity. ### Biodiversity of any region reflects the climatic diversity of that region The Indian subcontinent, which is situated between 8°4" and 37...

## Biogeographical Classification of India The biological area of India has been divided into 9 biogeographical regions on the basis of ecosystem diversity. ### Biodiversity of any region reflects the climatic diversity of that region The Indian subcontinent, which is situated between 8°4" and 37º6" N latitude and between 68° 7" and 97° 25" E longitude, provides diversified habitat conditions for vast biodiversity resources. For this reason, India is considered as a biodiversity rich nation. For botanical and geographical purposes, the Indian sub-continent can be divided into many regions. It was **Hooker (1955)** who for the first time started phytogeographical studies in India through his book *Flora indica*. Many other scientists and geographers attempted to work in this direction. These contributions of **Clark (1898), Hooker (1906), Razi (1955), Jain (1983) and Mehar-Homji (1984)** are appreciable. Different scientists and geographers have divided India into 8 to 21 floristic regions. The Wild Life Institute of India has divided India into 10 biogeographical regions. However, the classification given by **Chatterjee (1962)** is widely used. Based on the geographical features, Chatterjee divided India into nine floristic regions: 1. **The Western Himalayas** 2. **The Eastern Himalayas** 3. **The Western Desert** 4. **The Gangetic Plains** 5. **Central India** 6. **West Coast** 7. **Deccan Plateau** 8. **Assam** 9. **Andaman and Nicobar Islands** **1. The Western Himalayas** It extends from the central region of Kumaon to northwest region of Kashmir. There are three zones of vegetation corresponding to three climatic belts: * **Basal or submontane zone**: It extends from about 1,000 to 5,000 feet above sea level in regions of Siwaliks and adjacent areas. Important dominant trees of this region include *Dalbergia sissoo, Shorea robusta, Cedrela toona, Ficus glomerata etc*. * **Temperate or montane zone**: It extends from 5,000 to 11,675 feet above sea level. The average temperature is lower. Dominant trees of this region are *Pinus excelsa, Cedrus deodar, Betula, Salix, Cupressus torulosa, Taxus baccata etc*. * **Alpine zone**: It is the limit of tree growth at about 12,000 feet known as timber line or tree line, where the plant height considerably reduced. *Betulla utilis, Primula, Juniper, Rhododendron* etc. are the dominant plant species of this zone. **2. Eastern Himalayas** It consists of regions of Sikkim and extends upto highlands of Assam. This area is warmer and receives higher rainfall in comparison to the western Himalayas. This region is again divided into three vegetational zones: * **Tropical submontane zone**: It extends from the plain of the hill upto 6,000 feet. The dominant trees in this area are *Shorea robusta, Dalbergia sissoo, Acacia catechu, Anthocephalus cadamba etc.* * **Temperate zone**: It extends from 6,000 to 12,000 feet altitude above sea level. The dominant trees are *Quercus lamellosa, Michelia, Cedrella, Eugenia etc*. * **Alpine zone**: It is above 12,000 feet where vegetation is devoid of trees. In grassy areas shrubby growth of *Juniper and Rhododendron* is found. **3. Western Deserts** This region consists of parts of Rajasthan, Kutchh, Delhi and Gujarat. Rainfall is less than 70 cm. Due to high temperature and less rainfall xerophytic plants are common. Species of *Acacia nelotica, Prosopis spicigera, Prosopis juliflora, Capparis aphylla and Calotropis* are common. **4. Gangetic plains** This region comprises parts of Uttar Pradesh, Bihar and Bengal. This region is highly fertile. The climatic conditions like temperature and rainfall and the presence of alluvial soil provide favourable condition for plant growth. In Western margins, rainfall is less than 70 cm whereas it is more than 150 cm in eastern regions. Therefore, this region contains forests of dry deciduous to tropical moist types. In plains *Dalbergia sissoo, Shorea robusta etc* are common. In Vindhyan region deciduous species such as *Butea monosperma (Dhak), Diospyros melanoxylon (Bidi), Madhuca indica (Mahua), Terminalia arjuna (Arjun) Ficus religiosa (Peepal), Ficus bengalensis (Bargad) etc* are common. In the delta of Ganga and Brahmaputra Mangrove forests are found. **5. Central India** This biogeographical region comprises of those parts of M.P., Orissa and Northern Gujarat which are situated between the plains of Ganges and southern plateau. This area receives heavy rainfall (between 150-200 cm). The dominant tree species are *Shorea robusta (Sal), Tectona grandis (Sagwan), Diospyros melanoxylon (Bidi), Madhuca indica (Mahua), Mangifera indica (Mango), Cassia fistula (Amaltas), etc*. Important species among thorn forests include *Carissa spinarum, Ziziphus, Acacia catechu etc*. **6. Western Coast** This region is also known as Malabar. It extends from South Gujarat in North to Kanyakumari in South. Average rainfall is high. Four different types of forests are found: * **Tropical moist evergreen forests**: The height of trees is around 200 feet. Dominant trees are *Dipterocarpus indicus, Sterculia alata, Tectona grandis etc*. * **Mixed deciduous forests**: These are found in hilly regions of ghats upto a height of 5000 feet. The dominant tree species are *Terminalia, Lagerstroemia, Tectona grandis etc.* * **Temperate evergreen forests**: These forests are found on Nilgiris. The dominant tree species are *Michelia nilgrica, Eurya japonica, Gordonia obtusa etc.* * **Mangrove forests**: These include forests of coastal regions of Mumbai and Kerala. *Rhizophora, Avicennia etc.* are the dominant species. **7. Deccan Plateau** This region is dry and rocky. It includes parts of Andhra Pradesh, Tamil Nadu and Karnataka. It extends to the entire southern peninsula except the moist part of the western coast in the southern Godavari river. Dominant species are *Boswellia serrata, Tectona grandis, Hardwickia pinnata etc*. Eastern dry coromandal coast contains *Santalum album, Cedrela toona, Capparis and many other*. **8. Assam** This region receives the heaviest rainfall and hence dense tropical evergreen forests are common. Cherrapunji in this area receives rainfall more than 1000 cm. In the valley of Surma and Brahmaputra, *Dipterocarpus macrocarpus, Michelia champaca, Shorea robusta, Dendrocalamus etc* are important tree species. In hilly regions *Magnolia, Acer, Prunus, Pyrus, Rhododendron etc* are common. **9. Andaman and Nicobar Islands** It has a wide range of forests from coastal vegetation such as mangroves, beech forests to evergreen forests in the interior. There are some pockets of dry area also. Some of the areas have been cleared for cultivation. *Dipterocarpus, Mimusops, Calophyllum, Lagerstroemia, Terminalia* are important plant species of the region. *The image shows a map of India with the different biogeographical regions highlighted.*