Introduction
Vegetation is the plant cover of a region, and its type and composition depend mainly on altitude, temperature, rainfall and soil. Because Nepal rises from about 60 m in the tropical Tarai to over 8,000 m in the high Himalaya within a very short horizontal distance, it packs an unusually wide range of vegetation types, from tropical Sal forest to alpine meadows, into one small country. Conserving this plant (and associated animal) diversity is done through two complementary strategies, in-situ and ex-situ conservation.
Vegetation types of Nepal
Nepal's forests are classified into five broad altitudinal vegetation zones:
1. Tropical forest (below 1,000 m)
Found in the Tarai and lower Siwalik hills, where temperature and rainfall are highest.
- Sal forest: the most extensive and economically important tropical forest type, dominated by Shorea robusta (Sal), a valuable timber tree.
- Tropical deciduous riverine forest: grows along rivers and streams on alluvial soil, with species such as Toona ciliata.
- Tropical evergreen forest: found on humid, north-facing slopes, with species such as Michelia champaca.
2. Subtropical forest (1,000 to 2,000 m)
- Schima-Castanopsis forest: the dominant subtropical forest type between about 1,000 and 1,700 m, named for its two characteristic trees, Schima wallichii and Castanopsis indica.
- Pine forest: dominated by Pinus roxburghii (Chir pine), often on drier, south-facing slopes.
- Alder forest: dominated by Alnus nepalensis, typically colonising landslide and riverbank sites, extending up to about 2,700 m.