The Himalayan subtropical broadleaf forests is an

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of ...

that extends from the middle hills of central

Nepal Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne, सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is ma ...

through

Darjeeling Darjeeling (, , ) is a town and municipality in the northernmost region of the Indian state of West Bengal. Located in the Eastern Himalayas, it has an average elevation of . To the west of Darjeeling lies the easternmost province of Nep ...

into

Bhutan Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountainou ...

and also into the

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...

n States of

Uttar Pradesh Uttar Pradesh (; , 'Northern Province') is a state in northern India. With over 200 million inhabitants, it is the most populated state in India as well as the most populous country subdivision in the world. It was established in 195 ...

and

Bihar Bihar (; ) is a state in eastern India. It is the 2nd largest state by population in 2019, 12th largest by area of , and 14th largest by GDP in 2021. Bihar borders Uttar Pradesh to its west, Nepal to the north, the northern part of West ...

. It represents the east-west-directed band of subtropical broadleaf forest at an altitude of between along the Outer Himalayan Range, and includes several forest types traversing an east to west moisture gradient.Rawat, G. S., Wikramanayake, E. D. (2002
''Himalayan subtropical broadleaf forests''
In: Wikramanayake, E. D. (ed.) ''Terrestrial ecoregions of the Indo-Pacific: a conservation assessment''. Island Press

Geography

The ecoregion covers an area of and is bisected by the

Kali Gandaki River The Gandaki River, also known as the Narayani and the Gandak, is one of the major rivers in Nepal and a left bank tributary of the Ganges in India. Its total catchment area amounts to , most of it in Nepal. In the Nepal Himalayas, it is not ...

, which has gouged the world's deepest river valley through the

Himalaya The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 10 ...

n 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 Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. ...

deposited over the ages by the rivers that drain this young mountain range. At lower elevations, the ecoregion is flanked by the Terai-Duar savannas and grasslands. Above , it yields to the Himalayan subtropical pine forests.

Climate

Rainfall varies from east to west, but annual rainfall can be as much as . The Himalayas capture moisture from the

monsoon A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscil ...

s that sweep in from the

Bay of Bengal The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands of India. Its southern limit is a line bet ...

, 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 in the east to about in the west.

Flora

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

Indomalaya The Indomalayan realm is one of the eight biogeographic realms. It extends across most of South and Southeast Asia and into the southern parts of East Asia. Also called the Oriental realm by biogeographers, Indomalaya spreads all over the Indi ...

n and

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sib ...

biogeographic realm A biogeographic realm or ecozone is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into bioregions, which are further subdivided into ecoregions. ...

s. The main forest types include '' Dodonaea'' scrub, subtropical dry evergreen forests of ''

Olea cuspidata ''Olea europaea'' subsp. ''cuspidata'' is a subspecies of the well-known olive tree (''Olea europaea''), which until recently was considered a separate species (''Olea africana'') and is still mentioned as such in many sources. Native to northeas ...

'', northern dry mixed deciduous forests, dry

Siwalik The Sivalik Hills, also known as the Shivalik Hills and Churia Hills, are a mountain range of the outer Himalayas that stretches over about from the Indus River eastwards close to the Brahmaputra River, spanning the northern parts of the Indian ...

sal Sal, SAL, or S.A.L. may refer to: Personal name * Sal (name), a list of people and fictional characters with the given name or nickname Places * Sal, Cape Verde, an island and municipality * Sal, Iran, a village in East Azerbaijan Province * Ca ...

(''Shorea robusta'') forests, moist mixed deciduous forests, subtropical broadleaf wet hill forests, northern tropical semi-evergreen forests, and northern tropical wet evergreen forests.

Fauna

Several mammals native to the ecoregion are

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of '' critical depe ...

, including the

Bengal tiger The Bengal tiger is a population of the '' Panthera tigris tigris'' subspecies. It ranks among the biggest wild cats alive today. It is considered to belong to the world's charismatic megafauna. The tiger is estimated to have been present i ...

Indian elephant The Indian elephant (''Elephas maximus indicus'') is one of four extant recognised subspecies of the Asian elephant and native to mainland Asia. Since 1986, the Asian elephant has been listed as Endangered on the IUCN Red List as the wild pop ...

smooth-coated otter The smooth-coated otter (''Lutrogale perspicillata'') is an otter species occurring in most of the Indian subcontinent and Southeast Asia, with a disjunct population in Iraq. It is listed as Vulnerable on the IUCN Red List since 1996 and is threa ...

clouded leopard The clouded leopard (''Neofelis nebulosa''), also called the mainland clouded leopard, is a wild cat inhabiting dense forests from the foothills of the Himalayas through mainland Southeast Asia into South China. In the early 19th century, a ...

gaur The gaur (''Bos gaurus''; ), also known as the Indian bison, is a bovine native to South Asia and Southeast Asia, and has been listed as Vulnerable on the IUCN Red List since 1986. The global population was estimated at a maximum of 21,000 m ...

Sumatran serow The Sumatran serow (''Capricornis sumatraensis sumatraensis''), also known as the southern serow, is a subspecies of the mainland serow native to mountain forests in the Thai-Malay Peninsula and on the Indonesian island of Sumatra. It was previo ...

Irrawaddy squirrel The Irrawaddy squirrel (''Callosciurus pygerythrus'') or hoary-bellied Himalayan squirrel is a species of rodent in the family Sciuridae. Description Irrawaddy squirrels vary in fur color, some squirrels being greyish-brown and reddish-brown, ...

, and particoloured flying squirrel. The

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

golden langur Gee's golden langur (''Trachypithecus geei''), also known as simply the golden langur, is an Old World monkey found in a small region of Western Assam, India and in the neighboring foothills of the Black Mountains of Bhutan. Long considered sac ...

is distributed in a small range and limited to the broadleaf forest north of the

Brahmaputra River The Brahmaputra is a trans-boundary river which flows through Tibet, northeast India, and Bangladesh. It is also known as the Yarlung Tsangpo in Tibetan, the Siang/Dihang River in Arunachali, Luit in Assamese, and Jamuna River in Bangla. I ...

. The bird fauna is very rich with more than 340 species. The

chestnut-breasted partridge The chestnut-breasted partridge (''Arborophila mandellii'') is a partridge species endemic to the eastern Himalayas north of the Brahmaputra, and occurs in Bhutan, Darjeeling, Sikkim, Arunachal Pradesh and south-eastern Tibet at elevations from . ...

; the globally threatened

white-winged wood duck The white-winged duck or white-winged wood duck (''Asarcornis scutulata'') is a large species of duck, formerly placed in the genus ''Cairina'' with the Muscovy duck (''Cairina moschata'') and allied with the dabbling ducks. However, mtDNA cyto ...

and five

hornbill Hornbills (Bucerotidae) are a family of bird found in tropical and subtropical Africa, Asia and Melanesia. They are characterized by a long, down-curved bill which is frequently brightly coloured and sometimes has a casque on the upper mandibl ...

species are found here.

Protected areas

Eight protected areas extend into this ecoregion covering , which is about 7% of the ecoregion's area: *in India:

Sohagi Barwa Sanctuary Sohagi Barwa Wildlife Sanctuary is in the Maharajganj district in Uttar Pradesh state of India. It covers 428.2 km², located on the west Bank of the Gandaki River, near the border with Nepal. Sohagi Barwa is one of the tiger habitats of ...

and

Valmiki National Park Valmiki National Park is a Tiger Reserve in the West Champaran District of Bihar, India. It is the only national park in Bihar. Valmiki Tiger Reserve covers , which is 17.4% of the total geographical area of the district. As of 2018, there wer ...

; *in Nepal: Bardia National Park,

Chitwan National Park , iucn_category = II , location = Central Terai of Nepal , established = 1973 , nearest_city = Bharatpur , map = Nepal Bagmati Province#Nepal#India#South Asia , relief = 1 , label = Chitwan National Park , label_position = top , coordina ...

, Parsa National Park; *in Bhutan:

Royal Manas National Park Royal Manas National Park is Bhutan's oldest national park, and the Royal government considers it the "conservation showpiece of the Kingdom" and a "genetic depository" for valuable plants. It has an area of and covers eastern Sarpang District ...

Khaling Wildlife Sanctuary Jomotsangkha Wildlife Sanctuary (formerly ''Khaling Wildlife Sanctuary'') is the smallest protected area of Bhutan covering in Samdrup Jongkhar District along the southern border with Assam. Its elevations range between and . Khaling Wildlife ...

and Phibsoo Wildlife Sanctuary. Two high-priority

tiger The tiger (''Panthera tigris'') is the largest living Felidae, cat species and a member of the genus ''Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily pr ...

conservation units (TCU) extend across adjacent ecoregions:Wikramanayake, E.D., Dinerstein, E., Robinson, J.G., Karanth, K.U., Rabinowitz, A., Olson, D., Mathew, T., Hedao, P., Connor, M., Hemley, G., Bolze, D. (1999
''Where can tigers live in the future? A framework for identifying high-priority areas for the conservation of tigers in the wild''
. In: Seidensticker, J., Christie, S., Jackson, P. (eds.) ''Riding the Tiger. Tiger Conservation in human-dominated landscapes.'' Cambridge University Press, Cambridge. hardback , paperback *Chitwan-Parsa-Valmiki TCU covers a huge block of alluvial grasslands and subtropical moist deciduous forests; *Bardia-Banke TCU covers .

External links

References

{{Uttarakhand Ecoregions of Asia Ecoregions of Bhutan Ecoregions of the Himalayas Ecoregions of India Ecoregions of Nepal * * * Forests of India Himalayan forests Indomalayan ecoregions Tropical and subtropical moist broadleaf forests Forests of Nepal