The alpine zone (zone which lies between timber line and snow zone) includes in the descending order, a sub-snow zone immediately below the snow zone a meadow zone in the centre and a shrub zone which gradually merges into the timber zone.
According to Mani (1957) snow zone of Himalayas lies over 5100 m above mean sea level and alpine zone exists at a height of 3600 m. From an ecological view point, the zone above the limits of tree growth (timber line) exhibits extreme environmental conditions which greatly influence the biota of this region.
The characteristic features of high altitude environment are following—a low air density, low oxygen and carbon dioxide contents and water vapor, high ozone content, high atmospheric transparency affording greater penetration of light, cold, snow cover, increased rate of desiccation, high wind velocity, insulation of high intensity during the day and rapid radiation during the night, the high glare from the sky and snow, high intensity of ionizing radiation and the exclusion of trees.
Alpine zone of Himalayas is characterized by a sparseness of animal groups, the scarcity being relatively important as far as tropical Indian, South Chinese, Indo-Chinese and Malayan derivatives are concerned. Important constituents of the fauna of this zone are cold-adapted palaearctic forms (Mani, 1968).
Many invertebrates of alpine zone are predatory and occur in lakes, streams and ponds. Among vertebrates fishes and amphibians are totally lacking and reptilian fauna is greatly impoverished.
However, pelobatid frog, Aleurophryne mammata is found to occur at 4500 meters of height in Himalayas and viviparous Mabtiya varia has been reported to live at 4000 metres of height in Mount Kilimanjaro. Some of the representative vertebrates of Himalayan alpine zone are—crow Corvus corax; snow partridge Lerwa nivi-cola ; snow leopard Felis unica and Felis lynx ; European leech marten Mustek foina; the vole Lagomys; Tibetan yak Bos grunnius; Tibetan sheep Ovis hodgsoni; pamir sheep Ovis poli; ibex Capra sibricia; markhor Capra falconeri; and Persian wild goat Capra aegagrus.
A large number of insects and arachnids remain best adapted to Himalayan alpine zone and at 6900 meters height. The torrential streams which are the products of melting snow contain many mayflies, stoneflies and caddis flies.
Some of common insects of this zone are—stonefly Rhabdiopteryx lunata ; grasshoppers like Bryo- dema and Gomphomastax ; apterous species Conophyma ; Dicrano- phyma ; Sphingonotus ; tettigonid Hypsinomus fasciata ; earwigs like Anechura ; bugs like Dolmacoris, Tibetocoris, and Nysius ericae ; aquatic beetle Amphizoa ; carabids like Bembidion, Carabus, Calo- soma, Harpalus, Trechus, Calathus, Bradytus, Broscus, and Dyschi- rius ; staphylinids like Atheta, Aleochara, Geodromicus, Oxypoda, Philonthus and Tachinus; tenebrionids like Bioramix and Chianalus; ants like Formica picea ; bumble bees like Lapidariobombus sepa- randus ; butterflies like Colias, Argynnis and Parnassius ; the fly Deuterophelebia ; collembolans like Entomobrya, Isotoma, Prois- toma, Hypogastruca, Isotomurus, Tomocerus and Onychiurus; and numerous simulids, blepharocerids, syrphids, anthomyids, tachinids, and sarcophagids.