The Himalayan region stretches over a distance of about 2500 km from West to East. Its average width along the entire longitudinal extension ranges from 100 - 400 km. The vast area covered by the mountain range, along with some fantastic altitude gradients; resulting in tremendous bio-diversity of the Himalayan region. Vegetation and wildlife both change according to the varying altitude and the resulting differences in climatic conditions.
The forests of Himachal Pradesh are known for their grandeur and majesty and are like a green pearl in the Himalayan crown. The forests of the State can be broadly classified into coniferous forests and broad-leaved. Distribution of various species follows fairly regular altitudinal stratification. The vegetation varies from dry scrub forests at lower altitudes to alpine pastures at higher altitudes. In between these two extremes, distinct vegetation zones of mixed deciduous forests, bamboo, chil, oaks, deodar, kail, fir and spruce, are found. The richness and diversity of our flora can be estimated from the fact that, out of a total of 45,000 species found in the country, as many as 3,295 species (7.32%) are reported in the State. More than 95% of the species are endemic to Himachal Pradesh, and characteristic of western Himalayan flora, while about 5% (150 species) are exotic, introduced over the last 150 years.