Nepal has topographic variation from about 150 meters above sea level at the southern border to the highest mountain in the world (Everest at 8 848 m) in the north. Nepal has a tropical climate in the south and temperate and alpine climates in the north. Forest types also vary accordingly.

Forest types according to Altitudes (Source: http://www.forestrynepal.org/)


Forest Types
Altitude
Vegetation
Tropical Forests (in Terai, Bhavar regions)
Upto 1000masl from lowlands
Sal (Shorea robusta), Khair (Acacia catechu), Sissoo (Dalbergia sissoo), Characteristic grass species are Saccharum spontaneum, Phragmites karka, Arundo donax and Eulaliopsis binata in the grasslands, The forests are evergreen with trees suitable for high temperature and more rainfall.
Sub-Tropical Forests (in Siwalik hills, Southern part of Mahabharat Range)
1000 masl -2000 masl in the west
1000 masl -1700 masl in the east
Chir Pine (Pinus roxburghii), Schima wallichii, Castanopsis indica, Utis (Alnus nepalensis),  
Lower Temperate Forests (in Mahabharat Range , Middle mountainous region of Nepal)
2000 masl -2700 masl in the west
1700 masl -2400 masl in the east
Oak (Quercus species), Blue Pine (Pinus wallichiana),
Upper Temperate Forests 
2700 masl -3100 masl in the west and centre
 2400 masl -2800 masl in the east
Khasru (Quercus semecarpifolia), Rhododendron arboreum, Blue Pine (Pinus wallichiana), Juniperus indica, Cedrus deodara, Fir (Abies pindrow)
Plants of medicinal value are found abundantly.
Sub-Alpine Forests
3000 masl to 4200 masl in the west
around 3000 masl in the east
Fir (Abies spectabilis), Khasru (Quercus semecarpifolia), Rhododendron spp, Birch (Betula utilis), Juniperus indica
There is no tree in alpine zone, but shrubby rhododendrons and junipers and some other shrubby species (Hippophae rhamniodes, Cotoneaster microphyllus) are found at lower elevations, up to 4500 m.  Above 4500 m there is permanent snow cover.