Nepal is a tiny but diverse country not only in culture, language, and religion alone but also in flora and faunas.
The elevation of Nepal ranges from the lowland of the Terai (southern part of Nepal) to the highest peak in the world—the Mt. Everest. There are the most magnificent sceneries in Nepal and the great variety of flora and fauna. Its rich feature of diversity is incomparable elsewhere in the world. Between Nepal's geographical extremes, one may find every type of vegetation, from the treeless steppes of the Trans-Himalayan region, the birch, silver fir, larch and hemlock of the higher valleys to the oak, pine and rhododendron of the intermediate altitudes and the great Sal and Sissau forests of the south.
Nepal's flora and fauna can be divided into four regions:
1. Tropical Zone (up to 1000m)
This region includes the Terai (lowland) and the large valleys or Duns found between successive hill ranges. The main tree species of this area are Sal, Semal, Asia and many more and Pinus Rosburghi occurring on the higher ridges of the Churia hills, which reaches an altitude of 1800m. Two-meter high elephant grass originally covered much of the Dun valleys but now it has been largely replaced by agricultural settlements. This tropical zone is the richest area of Nepal for wildlife such as gaurs, buffaloes, leopards, four species of deer, tigers and some other animals like rhinoceros, swamp deer, and hot deer. Not only these, one can find two species of crocodile and the Gangetic dolphin in the rivers. The major birds are the peacock, jungle fowl, and black partridge, while migrated duck and geese swarm in the ponds and lakes in Terai.
2. Subtropical Zone (1100m-2400m)
This region includes the Mahabharat Lekh, which rises to the height of about 2400m and involves the outer wall of the Himalayan range. Great rivers such as the Karnali, Narayani, and Sapta Koshi flow through this area into the broad plains of the Terai. The trees one can find in this region are Acer oblongum, various species of oak and rhododendron which cover the higher slopes where deforestation has not yet taken place. Orchids clothe the stems of trees and gigantic climbers smother their heads. The variety and abundance of the flora and fauna increase progressively with decreasing altitude and increasing luxuriance of the vegetation.
This zone is generally poor in wildlife. The only mammals, which are at all widely distributed, are wild boar, barking deer, Crow, Ghoral, and bears. Different varieties of birds are also found in this zone and different varieties of birds are also found in this zone.
3. Temperate Zone (2500m- 4000m)
Northward, on the lower slopes and spurs of the great Himalayas, oaks and pines are the dominant species up to an altitude of about 2400m above which are found dense conifer forests including Picea, Tusga, Larix, and Abies-spp. The latter is usually confined to higher elevations with Betula typically marking the upper limit of the tree line. At about 3600 to 3900m, rhododendron, bamboo, and maples are commonly associated with the coniferous zone.
The composition of the forest varies considerably with coniferous predominating in the west and ericaceous in the east. The wildlife of this region includes the Himalayan bear, serow, ghoral, barking deer and wild-boar, with Himalayan thar sometimes being seen on steep rocky faces above 2400m. The red panda is among the more interesting of the mammals found in this zone; it appears to be fairly distributed in suitable areas of the forest above 1800m. The rich and varied avifauna of this region includes several spectacular and beautiful pheasants, including the Danfe pheasant, Nepal's national bird.
4. Sub alpine and Alpine Zone (More than 4000m)
Above the tree line, rhododendron, juniper scrub, and other woody vegetation may extend to about 4200m. This continues up to the lower limit of perpetual snow and ice at about 5100m. The mammalian faun is sparse and unlikely to include any species other than Himalayan marmots, mouse hare, that, musk deer, snow leopard and occasionally blue sheep. In former times, the wild Yak and great Tibetan sheep could also be seen in this region and there is possibility that some of them may still be survived in the areas like Dolpa and Humla, and birds like lammergeyer, snowcock, snow partridge, and bunting, with redstarts and dippers often seen along the streams and rivulets. Yaks are the only livestock, which thrives at high altitude. They serve both back and draught animals