very scanty due to low rainfall and overgrazing. Tropical Thorn Forests Tropical thorn forests occur in the areas which receive rainfall less than cm. These consist of a variety of grasses and shrubs. It includes semi-arid areas of south west Punjab, Haryana, Rajasthan, Gujarat, Madhya Pradesh and Uttar Pradesh.
In these forests, plants remain leafless for most part of the year and give an expression of scrub vegetation. Important species found are babool, ber , and wild date palm, khair, neem, khejri, palas , etc. Tussocky grass grows upto a height of m as the under growth. Montane Forests In mountainous areas, the decrease in temperature with increasing altitude leads to a corresponding change in natural vegetation.
Mountain forests can be classified into two types, the northern mountain forests and the southern mountain forests. Figure . : Deciduous Forests Figure . : Tropical Thorn Forests The Himalayan ranges show a succession of vegetation from the tropical to the tundra, which change in with the altitude.
Deciduous forests are found in the foothills of the Himalayas. It is succeeded by the wet temperate type of forests between an altitude of , - , m. In the higher hill ranges of northeastern India, hilly areas of West Bengal and Uttaranchal, evergreen broad leaf trees such as oak and chestnut are predominant. Between , - , m, pine forests are also well-developed in this zone, with Chir Pine as a very useful commercial tree.
Deodar, a highly valued endemic species grows mainly in the western part of the Himalayan range. Deodar is a durable wood mainly used in construction activity. Similarly, the chinar and the walnut, which sustain the famous Kashmir handicrafts, belong to this zone. Blue pine and spruce appear at altitudes of , - , m.
At many places in this zone, temperate grasslands are also found. But in the higher reaches there is a transition to Alpine forests and pastures. Silver firs, junipers, pines, birch and rhododendrons, etc. occur between , - , m.
However, these pastures are used extensively for transhumance by tribes like the Gujjars, the Bakarwals, the Bhotiyas and the Gaddis. The