Himalayan subtropical broadleaf forests

The ecoregion covers an area of 38,200 km² (14,700 sq mi) and is bisected by the Kali Gandaki River, which has gouged the world's deepest river valley through the Himalayan Range. It forms a critical link in the chain of interconnected Himalayan ecosystems, where altitudinal connectivity between the habitat types is important for ecosystem function. The soil is composed of alluvium deposited over the ages by the rivers that drain this young mountain range.[2]

At lower elevations, the ecoregion is flanked by the Terai-Duar savannas and grasslands. Above 1,000 m (3,300 ft), it yields to the Himalayan subtropical pine forests.

Rainfall varies from east to west, but annual rainfall can be as much as 2,000 mm (79 in). The Himalayas capture moisture from the monsoons that sweep in from the Bay of Bengal, and most of this rainfall is expended in the eastern Himalayas. Therefore, the western Himalayas are drier, a trend reflected in the timberline that declines from 4,000 m (13,000 ft) in the east to about 3,500 m (11,500 ft) in the west.[2]

The ecoregion hosts a broad range of plant communities, based on its complex topography, differing soils, and variations in rainfall from the drier west to the more humid east. Its location on the south slope of the Himalaya allows the intermingling of plants and animals from the Indomalayan and Palearctic biogeographic realms. The main forest types include Dodonaea scrub, subtropical dry evergreen forests of Olea cuspidata, northern dry mixed deciduous forests, dry Siwalik sal (Shorea robusta) forests, moist mixed deciduous forests, subtropical broadleaf wet hill forests, northern tropical semi-evergreen forests, and northern tropical wet evergreen forests.

Several mammals native to the ecoregion are threatened, including the Bengal tiger, Indian elephant, smooth-coated otter, clouded leopard, gaur, Sumatran serow, Irrawaddy squirrel, and particoloured flying squirrel. The endemic golden langur is distributed in a small range and limited to the broadleaf forest north of the Brahmaputra River. The bird fauna is very rich with more than 340 species. The chestnut-breasted partridge is endemic; the globally threatened white-winged wood duck and five hornbill species are found here.[2]

Eight protected areas extend into this ecoregion covering 2,710 km² (1,050 sq mi), which is about 7% of the ecoregion's area:[2]

• in India: Sohagi Barwa Sanctuary and Valmiki National Park;
• in Nepal: Bardia National Park, Chitwan National Park, Parsa National Park;
• in Bhutan: Royal Manas National Park, Khaling Wildlife Sanctuary and Phibsoo Wildlife Sanctuary.

Two high-priority tiger conservation units (TCU) extend across adjacent ecoregions:[3]

• Chitwan-Parsa-Valmiki TCU covers a 3,549 km² (1,370 sq mi) huge block of alluvial grasslands and subtropical moist deciduous forests;
• Bardia-Banke TCU covers 1,518 km² (586 sq mi).

• "Himalayan subtropical broadleaf forests". Terrestrial Ecoregions. World Wildlife Fund.