It's because part of himalayan range, much of it the mountain is covered with Himalayan subalpine conifer forests.
The Western Himalayan Sub-Alpine Conifer Forests represent the frontline of the forested ecoregions in the western Himalayan region, standing against the treeless alpine meadows to the north. This ecoregion plays a critical ecological role as part of the Himalayan ecosystem, with interconnected processes that extend from the Terai and Duar grasslands along the foothills to the high alpine meadows and boulder-strewn scree that lie above the treeline. Several Himalayan birds and mammals exhibit seasonal migrations up and down the steep mountain slopes and depend on contiguous habitat for these movements. If any of the habitat layers are lost or degraded, these movements can be disrupted. Therefore, conservation of this ecoregion is critical to maintain the biodiversity-species and processes-of this youngest and tallest mountain range on Earth.
(Source : World Wildlife Fund) ...