Western Himalayan Alpine shrub and meadows

• Category: Grassland, Tundra, and Human Biomes.
• Geographic Location: Asia.
• Summary: This mountain ecosystem is threatened by both climate change and grazing practices.

The Himalayan Alpine Shrub and Meadows biome, western section, is a Palearctic bioregion in the high Himalayas of Nepal, Tibet, and India. The biome lies between the tree line and the snowline, and roughly corresponds to 9,843–16,404 feet (3,000–5,000 meters) in elevation; the location of the snowline depends on moisture availability and may change from year to year. It occupies an area of more than 27,027 square miles (70,000 square kilometers). The Western Himalayan Alpine Shrub and Meadows is a montane ecozone with conifer forests immediately below it and snow or permanent ice above.

There is a strong moisture gradient from east to west in the biome, and precipitation generally is derived from the summer Asian monsoon season. Overall, the bioregion is moister than central Tibet, but less moist than the adjacent Eastern Himalayan Alpine Shrub and Meadows biome. The Kali Gandeki river valley is a major break in the Himalayan range; it acts as the eastern boundary between these two Himalayan biomes. Moving west, the biome includes western Nepal, and the Uttarakhand and Himachal Pradesh states in India, ending at the Himalayan divide created by the Sutlej River.

The Himalayan region has a variety of ecosystems and habitats that vary from tropical rainforest to tundra. Uplift of the Himalayas and the Tibetan Plateau not only generates the Asian monsoon, but also creates refuges and barriers for various species. The high altitude of ridges, combined with long deep valleys, has acted as a filtering point for species. More mobile species such as birds are able to penetrate farther from their source populations in India or China, so distribution is often a function of dispersal ability. Grasslands cover more than one-third of the Himalayan region; this particular biome is the midpoint between forest and ice.

The climate is mild, with cool summers and cold winters characterized by numerous microclimates. High summer solar radiation and relatively high precipitation from the Asian monsoon mean that these areas are fertile even with a relatively short growing season. Snow covers the ground in winter, and melts in April and May. This spring snowmelt swells the rivers downstream and provides additional moisture for plants. Unfortunately, the spring melt has begun occurring earlier each year—an effect of global warming—which disturbs many species that depend on the moist conditions that have occurred before the day length has increased sufficiently for growth.

Many days, especially during the rainy summer, are cloudy and have thick, long-lasting fogs. As is common in the Northern Hemisphere, the northern slopes are moister and cooler in temperature, and thus more closely resemble the neighboring biome to the east. Strong incoming solar radiation means that this area can have extreme diurnal temperature fluctuations, depending on cloudiness.

Vegetation

The lower elevation vegetation of this biome is dominated by low, shrubby rhododendrons (Rhododendron spp.) and birch (Betula utilis), with willow (Salix spp.) common along the shallow waterways. Many of the small rhododendrons are extremely colorful during their flowering season. Less-common species associated with the dwarf rhododendrons include Hippophae rhamnoides and Cotoneaster microphyllus, with Ephedra gerardiana and juniper (Juniperus spp.) occurring at higher elevations. These species often have medicinal or other value.

Scattered shrubs give way to rich alpine meadows at the higher elevations. During the spring and summer, these shrubs bloom with colorful flowers. The alpine pastures are known locally as bugyal. Shrubland areas typically host mixed communities with the genera Anemone, Aster, Delphinium, Doronicum, Gentiana, Meconopsis, Mertensia, Pedicularis, Polygonum, and Primula represented, among others. A large proportion of species in the meadows are endemic, or found in no other place on Earth; many are endangered.

Fauna

The best known of the fauna here is the snow leopard (Panthera uncia). This iconic feline species feeds on the numerous large ungulates that are supported by the alpine meadows, such as Sumatran serow (Capricornis sumatraensis), Himalayan tahr (Hemitragus jemlahicus), Himalayan musk deer (Moschus chrysogaster), and Himalayan blue sheep (Pseudois nayur). The biome potentially is also the edge of the range for brown bear (Ursus arctos) and Tibetan wolf (Canis lupus). Wild yak (Bos grunniens mutus) were once plentiful, but have been listed as endangered, with some sources even suspecting their extinction. The predominant fauna consists of small mammals that live in the underbrush, such as the Himalayan weasel (Mustela sibrica), the pale weasel (Amphipyra tragopoginis), the Himalayan palm civet (Paguma larvata), pikas (Ochotona himalayana), the mountain voles (Microtus montanus), and the silver mountain voles (Alticola argentatus).

Avian fauna consists of more than 130 species, including the golden eagle (Aquila chrysaetos) and Himalayan griffon (Gyps himalayensis). The bird fauna are much richer than the mammal fauna, because the species are able to move in and out of the biome more easily and thus avoid deleterious effects of the harsh winters.

Environmental Threats

A major threat to wildlife here is climate change, with its attendant shifting of temperature zones generally in an upslope direction and shifting of spring snowmelt runoff earlier in the season when downstream habitats cannot fully absorb the benefits. Researchers have noted that the temperature in the Himalayas has increased, especially in the winter and fall. The rising temperature has caused the treeline, the trees growing at the highest elevation, to move even higher. This can cause the meadows to shrink. Higher temperatures will make habitats unsuitable for some species. A study by the Zoological Survey of India has predicted the loss of 73 percent of the Himalayan brown bear habitat by 2050.

Other threats include fragmentation of habitat by overgrazing of sheep, yaks, and cattle. Nomadic herders use these meadows from May to October, and spend the winter at lower elevations. Poaching and hunting are additional threats.

Secondary negative human effects include firewood gathering in the shrublands by herders, as well as traders who move through the mountains from one country to another on long, centuries-old trade routes; and harvesting of plants for traditional medicines in all three countries. Numerous surveys have shown that the majority of people living in this biome extract at least some medicinal plants for personal use or for sale.

Studies have shown that in the future, changes in soil moisture from climate change will have a bigger effect on vegetation than current grazing patterns and human stressors. Getting a clear picture regarding climate change is difficult, however, as the extremely complex terrain has not been well modeled.

Grassland degradation results in changes in species composition; loss of species diversity; and loss of the dense sod layer, which provides nutrients and protects the vegetation growing in this area. When the sod layer is lost, only bare rock and mineral soils remain, and both these substances are unfertile and unable to store moisture effectively for vegetative growth. These systems cannot recover during human time scales, because of the severe environmental conditions, even if all disturbances were removed. As anthropogenic disturbances continue to grow, these problems will only grow worse.

Threats also include increases in tourism in these fragile areas. Equilibrium in grazing can be reached by local users. When visiting yaks carrying supplies for tourists enter the equation, however, there is little incentive for these interlopers to conserve resources, and increasing degradation can occur.

Conservation Efforts

There is a long history of biological protection in the area, from local resource preservation over the centuries to new national protected areas (PAs). The social customs and mythology in the Himalayan region are based on plants, animals, and the environment, which are often worshiped as minor deities. This has led to a cultural reverence for the natural world and restrained resource use in past centuries.

Grazing has long been the major use of this area, but customary relationships limited its effects. Growing populations and new market opportunities have led to a major increase in grazing, however. Overgrazing leads to a decline in palatable species for livestock and in loss of total biomass. Also, forbs are more prevalent than grasses in heavily grazed areas. Plant litter, which protects the soil from erosion and protects plant roots, is significantly lower in areas of high grazing. Generally, the drier the land, the more vulnerable it is to damage from overgrazing.

Significant PAs here include the Nanda Devi Biosphere Reserve in India and the Annapurna Conservation Area in Nepal. Although this biome has numerous PAs, the majority of them are mainly rock and ice, so there is less actual protected biome than the figures indicate. A study published in 2024 recognized the imbalance of protected areas, revealing a disconnect between biodiversity hotspots and areas that are listed as protected. The researchers indicated the need for PAs to be more biodiverse and populated by flora and fauna in order for conservation efforts to have the necessary effect.

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