Pastures and grasslands are products of dry semi-deserts but they have often resulted from degradation and destruction of forests into savannas. True pastures are found only in the sub-alpine and alpine areas in the higher altitudes of the Himalayas.
The grass cover in India is of three distinct types: the tropical, which is found in the plains, and the sub-tropical and the temperate which are found mainly in the Himalaya Mountains. These grasslands though not equivalent to steppe, pampas or savannah are generally divided into 3 types.
(i) Hilly or Upland Grasses:
They are found in Himalayas at a height above 1000 m while in the Western Ghats in Karnataka they are found where forests have been cleared up. In Nilgiris and other south Indian hills they are found in Shola forests.
(ii) Lowland Grasses:
These grasses are found in places where the rainfall varies from 31 cms. To 200 cms. With high summer temperatures and milder winters, such as in plains of Punjab, Haryana, Uttar Pradesh, Bihar and north-western parts of Assam. These grasses grow on a variety of soils and the species are both perennial and annual generally associated with well known breeds of cattle.
(iii) Riverine Grasses:
They are found in northern India such as Bhabar pastures occurring on alluvial sandy loam soil. These pastures are important grazing grounds for cattie and buffaloes.
The Western Himalayan region extends from Kashmir to Kumaon. Its temperate zone is rich in forests of chir, pine, other conifers and broad-leaved temperate trees. Higher up, forests of deodar, blue pine, spruce and silver fir occur.
The alpine zone extends from the upper limit of the temperate zone of about 4,750 metres or even higher. The characteristic trees of this zone are high-level silver fir, silver birch and junipers. The eastern Himalayan region extends from Sikkim eastwards and embraces Darjiling, Kurseong and the adjacent tract.
The temperate zone has forests of oaks, laurels, maples, rhododendrons, alder and birch. Many conifers, junipers and dwarft willows also occur here. The Assam region comprises the Brahmaputra and the Surma valleys with evergreen forests, occasional thick clumps of bamboos and tall grasses. The Indus plain region comprises the plains of Punjab, western Rajasthan and northern Gujarat.
It is dry and hot and supports natural vegetation. The Ganga plain region covers the area which is alluvial plain and is under cultivation for wheat, sugarcane and rice. Only small areas support forests of widely differing types. The Deccan region comprises the entire table land of the Indian Peninsula and support vegetation of various kinds from scrub jungles to mixed deciduous forests.
The Malabar region covers the excessively humid belt of mountain country parallel to the west coast of the Peninsula. Besides being rich in forest vegetation, this region produces important commercial crops, such as coconut, betelnut, pepper, coffee and tea, rubber and cashewnut. The Andaman region abounds in evergreen, mangrove, beach and diluvial forests.
The Himalayan region extending from Kashmir to Arunachal Pradesh through Nepal, Sikkim, Bhutan, Meghalaya and Nagaland and the Deccan Peninsula is rich in endemic flora with a large number of plants which are not found elsewhere.
India is rich in flora. Available data place India in the tenth position in the world and fourth in Asia in plant diversity. From about 70 per cent geographical area surveyed so far, 47,000 species of plants have been described by the Botanical Survey of India (BSI), Kolkata. The vascular flora, which forms the conspicuous vegetation cover, comprises 15,000 species.
Of these, more than 35 per cent is endemic and has so far not been reported anywhere in the world. The flora of the country is being studied by the BSI and its nine circle/field offices located throughout the country along with certain universities and research institutions.
Ethno-botanical study deals with the utilisation of plants and plant products by ethnic races. A scientific study of such plants has been made by BSI. A number of detailed ethno-botanical explorations have been conducted in different tribal areas of the country. More than 800 plant species of ethno-botanical interest have been collected and identified at different centres.
Owing to destruction of forests for agricultural, industrial and urban development, several Indian plants are facing extinction. About 1,336 plant species are considered vulnerable and endangered. About 20 species of higher plants are categorised as possibly extinct as these have not been sighted during the last 6-10 decades. BSI brings out an inventory of endangered plants in the form of a publication titled Red Data Book.