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Biotic resources refer to the plant and animal resources. India’s wide range in climate has led to rich and varied vegetation and an equally rich diversity of animal life.
According to the palaeo-botanists, most of our Himalayan and peninsular areas are covered with indigenous or endemic flora, while the Indo- Gangetic plain and the Thar Desert have plant species that have come generally from outside, that is, they are exotic.
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Nearly 40 per cent of our plant species are exotic. They have migrated from the trans-Himalayan areas. This natural vegetation is classified as boreal. In the context of vegetation, the word ‘boreal’ is generally used to denote coniferous forests.
The Indian plants whose origin is in the tropical region are called palaeo-tropical plants. The vegetation in the arid and semi-arid regions is influenced by the plants which came from North African regions. Those immigrating from Indo- Malaysia have influenced the vegetal cover of the hilly regions.
Diversity of Forest Resources:
A great variety of vegetation types exists from south to north and west to east. There is also great regional diversity in the foliage cover. Thus, one hectare of forest cover in the desert areas of Rajasthan may not be comparable to one hectare of forest cover in the hilly areas of Kashmir, Assam or Kerala.
The western slopes of the Western Ghats, which get more rain, have evergreen forests. These have also suffered over-utilisation. Kerala and Assam have tropically wet evergreen forests. In the drier parts of central India, Gujarat and Rajasthan, the vegetal cover ranges from tropical deciduous trees to thorny bushes. There is altitudinal change in vegetation in the Himalayas.
While the valley bottom has broad-leaved deciduous trees, the conifers extend towards the higher slopes. Generally, thick forest cover is either confined to inaccessible areas or in the areas of low density of population in the country. The monsoon forests, comprising tropical deciduous vegetation, extend between the rainfall zones of 100 cm and 200 cm.
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They have some of the economically valuable tree species. The North Indian Plains, extending from Punjab to West Bengal, are devoid of forest cover due to higher pressure of population and extension of cultivated land. The higher altitudes in Uttarakhand, Himachal Pradesh and Jammu and Kashmir are the main regions growing conifers, particularly deodar, pines and firs.
Broad-leaved sal and teak trees provide valuable timber. These trees occur in the terais of the Himalayas. Karnataka has sandalwood forests. The mangrove forests are found along the coasts abounding in delta areas. Sundarbans is known for Sundari trees.
Grasslands are found on the uplands where forest has been cleared—as in parts of Kashmir, Himachal Pradesh and Uttarakhand hills. In lowlands, the grasslands are found in the Indo- Gangetic plains and in Assam. There are certain riverine grasses like bhabhar grass in Terai area and elephant grass in Punjab. Grasslands are generally associated with good varieties of cattle like Gir, Hissar and Sahiwal, and buffaloes like Murrah and Mehsana.
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Major Indian Vegetation Types and their Specific Trees:
Forest 1. Tropical Evergreen Forest | Region Areas having 200-300 cm or more annual rainfall such as windward side of Western Ghats, North-eastern hills of India, Andaman and Nicobar Islands. | Important trees Rosewood, shisham, ebony, gurjan, toon, ironwood, etc. |
2. Tropical Deciduous Forests or Monsoon Forests | Areas having annual rainfall between 100-200 cm (in Orissa, Madhya Pradesh, Chhattisgarh, Jharkhand, Tamil Nadu and Karnataka) | Sal, teak, sandalwood, myrooalan, bamboo, rosewood, ebony, shisham, etc. |
3. Tidal or Littoral Forests | Areas of West Bengal, Orissa and Andhra Pradesh having annual rainfall above 200 cm (deltaic regions) | Sundari |
4. Mountain Forests | Eastern and Western Himalayas and Nilgiri regions of Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Kerala and Tamil Nadu | The type of trees depends on the height of mountain: sal (lower Shiwalik range); chir and ahil (higher range); and pine, cedar, fir, spruce (1,600-3,300 m). |
5. Thorn Forests | Areas of Rajasthan, Punjab and Gujarat having annual rainfall between 25 and 80 cm | Khajuri, khair, kikar and babul |
As for fauna or animal resources, according to the Zoological Survey of India, India has over 89,000 species of which protista number 2,577, mollusca 5,070, anthropoda 68,390, amphibia 209, mammalia 390, reptilia 456, members of protochordata 119, pisces 2,546, aves 1,232 and other invertebrates 8,329.
Among the mammals are the elephant, the gaur or Indian bison (the largest of existing bovines), the great Indian rhinoceros, the gigantic wild sheep of the Himalayas, the swamp deer, the thamin spotted deer, nilgai, the four-horned antelope, and the Indian antelope or black-buck— the only representatives of these genera.
Among the cats, the tiger and lion are the most striking of all; then there are the clouded leopard, the snow leopard and the marbled cat. Several birds, like pheasants, geese, ducks, myanahs, parakeets, pigeons, cranes, hornbills and sunbirds inhabit forests and wetlands.
Rivers and lakes are home to crocodiles and gharials, the latter being the only representative of this crocodilian order in the world. The salt water crocodile is found along the eastern coast and in the Andaman and Nicobar Islands.
The great Himalayan range is home to the wild sheep and goats, markhor, ibex, shrew and tapir. The panda and the snow leopard are found in the upper reaches of the mountains.