Brahmaputra Valley semi-evergreen forests

Brahmaputra Valley semi-evergreen forests

Ecology
Biome	Tropical moist broadleaf forest
Bird species	370^[1]
Mammal species	122^[1]
Geography
Area	56,700 km² (21,900 sq mi)
Countries	Bhutan and India
Conservation
Protected	5%^[1]

The Brahmaputra Valley semi-evergreen forests is a tropical moist broadleaf forest ecoregion of eastern India and southern Bhutan.

Location and description

The ecoregion covers 56,700 square kilometers (21,900 sq mi) and encompasses the alluvial plain of the upper Brahmaputra River as it moves westward through India's Assam state (with small parts of the ecoregion in the states of Arunachal Pradesh and Nagaland and also south Bhutan). The valley lies between the Himalayas to the north and the Lushai hills to the south and when the river floods during the June to September monsoon it brings up to 300 cm of water onto the plain carrying rich soils to create a fertile environment which has been extensively farmed for thousands of years. Other rivers that water the plains as well as the Brahamaputra include the Manas and the Subansiri.^[1]

Flora

The extensive farming has meant that the original semi-evergreen forest now exists only in patches. Typical canopy trees include the evergreen Syzygium, Cinnamomum and Magnoliaceae along with deciduous Terminalia myriocarpa, Terminalia citrina, Terminalia tomentosa, Tetrameles species. Understory trees and shrubs include the laurels Phoebe, Machilus, and Actinodaphne, Polyalthias, Aphanamixis, and cultivated Mesua ferrea and species of mahogany, cashews, nutmegs and magnolias, with bamboos such as Bambusa arundinaria and Melocanna bambusoides.

Fauna

Despite the centuries of human clearance and exploitation, the forests and grasslands along the river remain a habitat for a variety of wildlife including tiger (Panthera tigris), clouded leopard (Pardofelis nebulosa), capped langur, (Semnopithecus pileatus), gaur (Bos gaurus), barasingha deer (Cervus duvaucelii), sloth bear (Melursus ursinus), wild water buffalo (Bubalus arnee), India's largest population of Asian elephants (Elephas maximus) and the world's largest population of Indian rhinoceros, while Asian black bears live in the higher slopes of the valley sides. Most of these mammals are threatened or endangered species. The Brahmaputra is a natural barrier to the migration of much wildlife and many species, such as the pygmy hog, hispid hare, or the Malayan sun bear, pig-tailed macaque, golden langur, stump-tailed macaque, western hoolock gibbon live on one side of the river only. The area is a meeting point of species of Indian and Malayan origin. The endemic mammals of the valley are the pygmy hog and the hispid hare, both of which inhabit the grasslands of the riverbanks.

The valley is home to rich bird life with 370 species of which two are endemic, the Manipur bush quail (Perdicula manipurensis) and the marsh babbler (Pellorneum palustre) and one, the Bengal florican is very rare. Woodland birds like kalij pheasant, great hornbill, rufous necked hornbill, brown hornbill, Oriental pied hornbill, grey hornbill, peacock pheasant and tragopan are quite common.

Threats and preservation

This area has been densely populated for centuries and most of the valley has been and still are used for agriculture but some blocks of natural habitat do remain, mainly in national parks the largest of which are Manas, Dibru-Saikhowa and Kaziranga National Parks in India. In Bhutan, these areas are part of Royal Manas National Park.

Protected areas

In 1997, the World Wildlife Fund identified twelve protected areas in the ecoregion, with a combined area of approximately 2,560 km², that include 5% of the ecoregion's area.^[2]

Mehao Wildlife Sanctuary, Arunachal Pradesh (190 km², also includes portions of the Eastern Himalayan broadleaf forests and Himalayan subtropical pine forests)
Manas National Park, Assam (560 km²)
Bornadi Wildlife Sanctuary, Assam (90 km²)
Kaziranga National Park, Assam (320 km²)
Orang National Park, Assam (110 km²)
Laokhowa Wildlife Sanctuary, Assam (170 km²)
Pobitora Wildlife Sanctuary, Assam (80 km²)
Sonai Rupai Wildlife Sanctuary, Assam (160 km²)
Nameri National Park, Assam (90 km²)
Dibru-Saikhowa National Park, Assam (490 km²)
D'Ering Memorial Wildlife Sanctuary, Arunachal Pradesh (190 km²)
Pabha Wildlife Sanctuary, Assam (110 km²)

References

1 2 3 4 "Brahmaputra Valley semi-evergreen forests". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 2011-11-26.
↑ Wikramanayake, Eric; Eric Dinerstein; Colby J. Loucks; et al. (2002). Terrestrial Ecoregions of the Indo-Pacific: a Conservation Assessment. Island Press; Washington, DC. pp. 298-301

Ecoregions of India
Tropical and subtropical moist broadleaf forests	Andaman Islands rain forests Brahmaputra Valley semi-evergreen forests Chin Hills-Arakan Yoma montane forests Eastern highlands moist deciduous forests Himalayan subtropical broadleaf forests Lower Gangetic Plains moist deciduous forests Malabar Coast moist forests Maldives-Lakshadweep-Chagos Archipelago tropical moist forests Meghalaya subtropical forests Mizoram-Manipur-Kachin rain forests Nicobar Islands rain forests North Western Ghats moist deciduous forests North Western Ghats montane rain forests Orissa semi-evergreen forests South Western Ghats moist deciduous forests South Western Ghats montane rain forests Sundarbans freshwater swamp forests Upper Gangetic Plains moist deciduous forests
Tropical and subtropical dry broadleaf forests	Central Deccan Plateau dry deciduous forests Chota-Nagpur dry deciduous forests East Deccan dry evergreen forests Kathiarbar-Gir dry deciduous forests Narmada Valley dry deciduous forests Northern dry deciduous forests South Deccan Plateau dry deciduous forests
Tropical and subtropical coniferous forests	Himalayan subtropical pine forests Northeast India-Myanmar pine forests
Temperate broadleaf and mixed forests	Eastern Himalayan broadleaf forests Western Himalayan broadleaf forests
Temperate coniferous forests	Eastern Himalayan subalpine conifer forests Western Himalayan subalpine conifer forests
Tropical and subtropical grasslands, savannas, and shrublands	Terai-Duar savanna and grasslands
Montane grasslands and shrublands	Eastern Himalayan alpine shrub and meadows Karakoram-West Tibetan Plateau alpine steppe Northwestern Himalayan alpine shrub and meadows Western Himalayan alpine shrub and meadows
Flooded grasslands and savannas	Rann of Kutch seasonal salt marsh
Deserts and xeric shrublands	Deccan thorn scrub forests Indus Valley desert Northwestern thorn scrub forests Thar desert
Mangrove	Godavari-Krishna mangroves Indus River Delta-Arabian Sea mangroves Myanmar coast mangroves Sundarbans mangroves
Ecoregions of India

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