Once the tree-line is reached, only shrublets and small grasses, sedges and alpine plants survive within the alpine meadows and pasturelands. Here, once again, there is amazing diversity. Above the alpine meadow region, however, the alpine zone extends to the permanent summer snow-line which
harbours its own limited range of species that are hardy and adaptable to extremes of temperature, especially cold; and also extreme desiccation during the periods of permanent snow cover, which could range from two or three to almost ten months a year and even throughout the year, but here plants would not be able to survive.

Precipitation plays an equally important role in governing the diversity of floral species and composition in the Himalaya. Most of the precipitation is received during the late summer months and the early winter. The late summer period of rainfall, known as the monsoon, primarily reaches the Himalaya through the South-west Monsoon via the Bay of Bengal and to a lesser extent from the Arabian Sea. The monsoon rains usually reach our portion of the Western Himalaya in early to middle July and recede only in early September.

The effect of the monsoon rains depends on an area's location. The Himalaya act as a barrier and prevent the monsoon from having any effect on trans-Himalayan regions to the north, such as Tibet. Less protected regions such as Garhwal and Kumaon receive abundant rains during the monsoon months, but the effect decreases as one moves north through north-western Himachal Pradesh and towards Kashmir, the latter being protected by the Pir Panjal range which lies directly in the course of the South-west monsoon arriving from the Bay of Bengal.

This difference in the receipt of monsoonal rains can also be a local phenomenon created by geographical barriers. An example of this would be the high receipt of annual rainfall in the Tons valley of Garhwal. Parts of Himachal Pradesh, only slightly to the north of the Tons valley, such as Sangla and Baspa, experience only a third of the annual rainfall received in the Tons watershed. This may be attributed to the presence of several high mountain ranges, such as those of Swargarohini and Banderpunch, all exceeding 6000 m in altitude that lie at the head of the Tons valley and block the advancement of monsoon clouds to the regions in the north that thus experience a local rainshadow effect.

However, the monsoons are not the only major source of precipitation in the Himalaya, unlike in the plains of India where they play a vital role in the renewal of water reservoirs and in the refilling of groundwater reserves. In the Himalaya, a major portion of the annual precipitation is received in the form of winter rain in the lower regions and snowfall in the higher reaches.

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