Eastern Himalayan alpine shrub and meadows

July 5, 2012, 8:31 pm
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Kanchenjunga Conservation Area, Nepal Photograph by Chris Carpenter

The Eastern Himalayan Alpine Shrub and Meadows ecoregion supports one of the world's richest alpine floral displays that becomes vividly apparent during the spring and summer when the meadows explode into a riot of color from the contrasting blue, purple, yellow, pink, and red flowers of alpine herbs. Rhododendrons characterize the alpine scrub habitat closer to treeline. The tall, bright-yellow flower stalk of the noble rhubarb, Rheum nobile (Polygonaceae), stands above all the low herbs and shrubs like a beacon, visible from across the valleys of the high Himalayan slopes.

The plant richness in this ecoregion sitting at the top of the world is estimated at more than 7,000 species, a number that is three times what is estimated for the other alpine meadows in the Himalayas. In fact, from among the Indo-Pacific ecoregions, only the famous rain forests of Borneo are estimated to have a richer flora. Within the species-rich landscape are hotspots of endemism, created by the varied topography, which results in very localized climatic variations and high rainfall, enhancing the ability of specialized plant communities to evolve. Therefore, the ecoregion boasts the record for a plant growing at the highest elevation in the world: Arenaria bryophylla, a small, dense, tufted cushion-forming plant with small, stalkless flowers, was recorded at an astonishing 6,180 m by A. F. R. Wollaston.

Location and General Description

 

The Eastern Himalayan Alpine Shrub and Meadows represent the alpine scrub and meadow habitat along the Inner Himalayas to the east of the Kali Gandaki River in central Nepal. Within it are the tallest mountains in the world-Everest, Makalu, Dhaulagiri, and Jomalhari-which tower far above the Gangetic Plains. The alpine scrub and meadows in the eastern Himalayas are nested between the treeline at 4,000 meters (m) and the snowline at about 5,500 m and extend from the deep Kali Gandaki gorge through Bhutan and India's northeastern state of Arunachal Pradesh, to northern Myanmar.

In addition to being the world's tallest mountain range, the Himalayas are also one of the youngest. Their origin has been traced back to the collision between the northward-drifting Deccan Plateau and the northern Eurasian continent. During this collision the northern edge of the Deccan Plateau pushed beneath Eurasia and began to raise the northern continent from beneath the Tethys Sea to create what is now the Tibetan Plateau, 4,000 m above sea level. The Himalayan mountains were thrust upward during subsequent geologic uplifts and upheavals to form the highest mountain range in the world .

The eastern Himalayas are wetter than the western extents of the mountain range because of precipitation from the May-September southwest monsoon. The water it brings from the Bay of Bengal is first intercepted and expended here. But within this general trend, the complex topography creates rainshadows, resulting in very localized climatic variations. For instance, Pokhara, in the southern Annapurna Range, faces the brunt of the monsoonal rains and receives more than 3,500 millimeters (mm) of annual rainfall, but Jomsom, just 65 kilometers (km) north and in Pokhara's rainshadow, gets only 300 mm of rainfall. Aspect is another important criterion that determines local climatic variation. The north-facing slopes are less exposed to sunlight and are thus cooler and retain more moisture. Therefore, they are more likely to harbor a specialized Himalayan flora adapted to these moist, microclimatic conditions.

The scrub vegetation of this ecoregion is dominated by colorful Rhododendron species that exhibit high species turnover along the west-east gradient from eastern Nepal to northern Myanmar. For instance, some common species in the Nepal alpine scrublands, Rhododendron campanulatum, R. wallichi, R. campylocarpum, R. thomsonii, and R. wightii drop out of the assemblage in Bhutan, where R. bhutanense, R. aeruginosum, R. succothii, R. fragariiflorum, R. pumilum, R. baileyi, and R. pogonophyllum are added to the assemblage. And further east in northern Myanmar, the characteristic assemblage consisting of R. calciphila, R. crebriflorum, R. chryseum, R. riparium, R. sanguineum, and R. saluenense is entirely different.

caption Kanchenjunga Conservation Area, Nepal. (Photograph by Chris Carpenter)

The herbs that lend springtime color to the alpine meadows include hundreds of species from genera such as Alchemilla, Androsace, Primula, Diapensia, Impatiens, Draba, Anemone, Gentiana, Leontopodium, Meconopsis, Saxifraga, Sedum, Saussurea, Rhododendron, Potentilla, Pedicularis, and Viola. Several of these (e.g., Picrorhiza, Rheum, Aconitum, and Paris) are prized as medicinal herbs. The splendor and richness of these meadow communities in full bloom are difficult to describe.

The upper elevations of the ecoregion transition into rock screes, where shallow soils support grasses, cushion-forming plants, and rhododendron scrub among large boulders and craggy rock faces.

Biodiversity Features

The fauna of this ecoregion is surprisingly rich in large vertebrates. Important mammal species include the snow leopard (Uncia uncia), which roams the high-altitude meadows; blue sheep (Pseudois nayur); Himalayan tahr (Hemitragus jemlahicus); and the formidable takin (Budorcas taxicolor). Avian predators such as the lammergeier (Gypaetus barbatus), Himalayan griffon (Gyps himalayensis), black eagle (Ictinaetus malayensis), and northern goshawk (Accipiter gentilis) soar high among the peaks searching for colonial marmots (Marmota himalayana), which build extensive burrows in which they gain refuge.

The ecoregion harbors about 100 mammal species, but because the small and mid-sized mammals are poorly studied in this inaccessible habitat, this number probably is only a conservative estimate. Only one species is considered near endemic to this ecoregion (table 1). The Vespertilionid bat is also found in the Karakoram-West Tibetan Plateau Alpine Steppe ecoregion, much further west, and probably inhabits several other ecoregions.

Table 1. Endemic and Near-Endemic Mammal Species.
Family Species
Vespertilionidae Eptesicus gobiensis
An asterisk signifies that the species' range is limited to this ecoregion.

There are several threatened species such as the endangered snow leopard, takin, and Himalayan goral (Naemorhedus baileyi), and the vulnerable serow (Capricornis sumatraensis) and Himalayan tahr (Hemitragus jemlahicus) (in eastern Nepal and Sikkim) in this ecoregion. A recent record of a single takin bull was reported from Sikkim, far from the nearest known takin population in Jigme Dorji National Park in Bhutan.

The 115 bird species known in this ecoregion include one near-endemic species (table 2). This partridge is limited to the eastern Himalayas and is also found in the adjacent Himalayan Subtropical Broadleaf Forests, Eastern Himalayan Broadleaf Forests, and Eastern Himalayan Sub-Alpine Conifer Forest.

Table 2. Endemic and Near-Endemic Bird Species.
Family Common Name Species
Phasianidae Chestnut-breasted partridge Arborophila mandellii
An asterisk signifies that the species' range is limited to this ecoregion.

There are several other high-elevation specialists, such as the Himalayan snowcock (Tetraogallus himalayensis), Tibetan partridge (Perdix hodgsoniae), snow partridge (Lerwa lerwa), Satyr tragopan (Tragopan satyra), lammergeier, and the Himalayan griffon, that also need conservation attention.

Current Status

The ecoregion has fourteen protected areas that cover more than 11,680 km2, including several-such as Annapurna, Makalu Barun, Sagarmatha, Jigme Dorgi, and Sakteng-that exceed 1,000 km2 (or, as in the case of Annapurna and Jigme Dorji, 2,500 km2) (table 3). Although the total area protected represents about 30 percent of the ecoregion's area, the reserves are inequitably distributed. Most of the protected areas are in Nepal and Bhutan, whereas the eastern section of the ecoregion, especially in Myanmar, receives little or no formal protection. Because of the high species turnover along the east-west axis, more equitable protection is necessary for better representation of the ecoregion's biodiversity. Moreover, about half of the areas that lie within the existing protected areas represent bare rock and areas covered with permanent ice, not very important habitat for biodiversity conservation.

Table 3. WCMC (1997) Protected Areas That Overlap with the Ecoregion.
Protected Area Area (km2) IUCN Category
Langtang National Park 790 II
Makalu-Barun National Park 1,500 II
Sagarmatha National Park 1,110 II
Makalu-Barun Conservation Area 450 II
Torsa 110 I
Jigme Dorji 2,510 II
Sakteng WS 1,050 IV
Black Mountain 70 II
Thrumsing La 530 II
Walong National Park/WS 180 ?
Dong Jiu 220 ?
Mo Tuo 120 ?
Dibang Valley 380 PRO
Annapurna Conservation Area 2,660  
Total 11,680  
Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.

Types and Severity of Threats

The assessment of the habitat based on satellite imagery indicates that there is very little habitat loss, but ground surveys indicate widespread habitat degradation. Overgrazing and trampling by large herds of livestock (especially yak) and the unregulated commercial harvest of medicinal plants are the main threats to biodiversity in this ecoregion. These threats extend to the protected areas, so these fragile ecosystems lack effective core protection.

Snow leopards are hunted for their pelts but are also killed by herders, who consider them to be livestock predators. Herders also claim that large herbivores compete with livestock for food.

Justification of Ecoregion Delineation

In a previous analysis of conservation units, MacKinnon divided the Himalayan Range into four subunits along the longitudinal axis: the Northwest Himalayas, West Nepal, Central Himalayas, and Eastern Himalayas. In doing so, he included all the habitat types, from subtropical broadleaf forests in the lowlands to the alpine habitats, within each subunit. In defining ecoregions, we strove to delineate distinct habitats of regional extent as separate ecoregions. Therefore, we distinguished between the bands of habitat types along the latitudinal axis of the Himalayan Range and placed them within individual ecoregions. We used the Kali Gandaki River, widely considered a biogeographic barrier that defines the eastern and western Himalayan biotas, as a boundary to separate the eastern Himalayan alpine meadows and shrublands from the western alpine meadows and scrublands. We used the digital map of the habitat types of the Himalayas from MacKinnon, aided by a DEM, to delineate the northern and southern boundaries of the alpine meadows and scrub, and placed them in the Eastern Himalayan Alpine Shrub and Meadows. All the Himalayan ecoregions are part of Udvardy's Himalayan highlands biogeographic province.

Additional information on this ecoregion

Disclaimer: This article is taken wholly from, or contains information that was originally published by, the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

 

Glossary

Citation

Fund, W. (2012). Eastern Himalayan alpine shrub and meadows. Retrieved from http://www.eoearth.org/view/article/151906

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