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Himalayan subtropical pine forests

The Himalayan Subtropical Pine Forests [IM0301] are the largest in the Indo-Pacific region. They stretch throughout most of the 3,000-km length of this the world's youngest and highest mountain range. Some scientists believe that climate change and human disturbance are causing the lower-elevation oak forests to be gradually degraded and invaded by the drought-resistant Chir pine (Pinus roxburghii), the dominant species in these subtropical pine forests. Biologically, the ecoregion does not harbor exceptionally high levels of species richness or endemism, but it is a distinct facet of the region's biodiversity that should be represented in a comprehensive conservation portfolio.

  • Scientific Code
    (IM0301)
  • Ecoregion Category
    Indo-Malayan
  • Size
    29,400 square miles
  • Status
    Vulnerable
  • Habitats


 Description
Location and General Description
The subtropical pine forests represented by this ecoregion extend as a long, disjunct strip from Pakistan in the west, through the states of Jammu and Kashmir, Himachal Pradesh, and Uttar Pradesh in northern India, into Nepal and Bhutan. Although Champion and Seth (1968) indicate the presence of large areas of Chir pine in Arunachal Pradesh, the easternmost extent of large areas of Chir pine is in Bhutan.

The world's deepest river valley, the Kali Gandaki, bisects the ecoregion in Nepal, dividing it into a drier, western conifer forest and a wetter and richer eastern conifer forest. However, the species assemblages, community structure, and ecosystem dynamics are not sufficiently different to separate this pine forest into eastern and western ecoregions, as was done for the broadleaf forest ecoregions.

The Himalayan Mountain Range was formed about 50 million years ago, when the northward drifting Deccan Plateau collided with the northern Eurasian continent.

The mountain range is now made up of three east-west-directed parallel zones, with the southernmost Outer Himalayas, also known as the Siwaliks, lying adjacent to the Indo-Gangetic Plain. The next is the Middle Himalayas, representing a series of ridges and valleys that rise to about 5,000 m, and the third is the Inner Himalayas with imposing high peaks such as Everest, Makalu, and Dhaulagiri.

Most of the rainfall is brought by the southwestern monsoon from the Bay of Bengal. The monsoon rains are intercepted and expended in the eastern Himalayas, which are closer to the Bay of Bengal; therefore, the western region receives less precipitation. The climatic gradient influences the vegetation in the Himalayas. For instance, the treeline in the western Himalayas is more than 500 m lower than in the east (Kendrick 1989).

The dominant species in this belt of subtropical pine forest is Chir pine. Because of frequent fires, pine forests do not have a well-developed understory. However, frequently burnt slopes support a rich growth of grasses including Arundinella setosa, Imperata cylindrica, Themeda anathera, and Cymbopogon distans and a number of shrubs such as species of Berberis, Rubus, and other thorny bushes (Shrestha and Joshi 1997).

In Himachal Pradesh, extensive patches of Chir pine grow on the lower parts of Kangra and Una Districts, but toward the eastern parts of Himachal Pradesh and in the lower areas of the Uttar Pradesh hills, Chir pine grows in scattered patches commonly in association with Shorea robusta, Anogeissus latifolia, and Cordia vestita (Rawat and Mukherjee 1999). Extensive Chir pine plantations are present in Himachal Pradesh and in northwestern Uttar Pradesh.

In western Nepal, Chir pine forests predominate on all aspects of the slope, in contrast to areas further west, where they develop mainly on the southern slopes. In central and eastern Nepal, this ecoregion covers parts of the Siwalik and Mahabharat ranges on the south-facing slopes between 1,000 and 2,000 m (Shrestha and Joshi 1997).

Biodiversity Features
Compared with the adjacent broadleaf forests, this ecoregion is neither exceptionally rich in species nor high in endemic species. However, it does provide habitat to several endemic bird species that are found in adjacent ecoregions.

The ecoregion's mammal fauna consists of about 120 species. Most of the mammals are not specialized or limited to this ecosystem. Because of the lack of undergrowth and browse, the ecoregion does not support a significant herbivore community. Therefore, the carnivore community that is dependent on the herbivore (i.e., prey) density is also depressed. Some of the characteristic mammals that can be used as focal species in this ecoregion include goral (Nemorhaedus goral), barking deer (Muntiacus muntjak), and yellow-throated marten (Martes flavigula).

The bird fauna consists of 480 species, including 11 species that are endemic to this ecoregion (table 1). However, none of these species are strict endemics (i.e., limited to this ecoregion), being shared with adjacent ecoregions.

Table 1. Endemic and Near-Endemic Bird Species.

Family Common Name Species
Phasianidae Chestnut-breasted partridge Arborophila mandellii
Phasianidae Cheer pheasant Catreus wallichi
Timaliidae Ludlow's fulvetta Alcippe ludlowi
Turdidae Rusty-bellied shortwing Brachypteryx hyperythra
Timaliidae Elliot's laughingthrush Garrulax elliotii
Timaliidae Immaculate wren-babbler Pnoepyga immaculata
Timaliidae Snowy-throated babbler Stachyris oglei
Timaliidae Hoary-throated barwing Actinodura nipalensis
Timaliidae Spiny babbler Turdoides nipalensis
Timaliidae Mishmi wren-babbler Spelaeornis badeigularis
Phasianidae Western tragopan Tragopan melanocephalus

An asterisk signifies that the species' range is limited to this ecoregion.

This ecoregion overlaps with two of BirdLife International's EBAs: Eastern Himalayas (128) and Western Himalayas (130) (Stattersfield et al. 1998).

Current Status
More than half of this ecoregion's natural habitat has been cleared or degraded. In central and eastern Nepal, terraced agriculture plots, especially between 1,000 and 2,000 m, have replaced nearly all the natural forest. Other than in the less populated western regions, little natural forest remains in Nepal. Similarly, habitat loss is widespread in Pakistan, Jammu and Kashmir, and Himachal Pradesh and Uttar Pradesh states in India. The few larger blocks of remaining habitat blocks are now found in Bhutan.

There are twenty-six protected areas in the ecoregion that cover a little over 3,000 km2, representing about 4 percent of its area (table 2). Most of these protected areas are small (average 119 km2). Four protected areas extend into adjacent ecoregions, but with the exception of Corbett National Park that exceeds 500 km2, these are also small reserves.

Table 2. WCMC (1997) Protected Areas That Overlap with the Ecoregion.

Protected Area Area (km2) IUCN Category
Ayubia 140 V
Margalla Hills 100 V
Kazinag GR 70 II
Moji WS 80  
Hirapora [IM0403] 70 IV
Mori Said Ali GR 50  
Killan GR 80  
Nargu [IM0403] 170 IV
Askot [IM0403] 80 IV
Shikari Devi 80 IV
Bandli 10 IV
Gobind Sagar 180 IV
Naina Devi 40 IV
Majathal 20 IV
Darlaghat 120 IV
Simla Water Catchment 40 Ia
Chail 130 IV
Shilli 2 IV
Talra 40 IV
Corbett [IM0166] 310 II
Fambong Lho 50 IV
Maenam 50 IV
Kane 50 IV
Pakhui 860 IV
Itanagar 190 IV
Sessa Orchid 100 IV
Total 3,112  

Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.

Types and Severity of Threats
Threats to the forests in this densely populated ecoregion include overgrazing, overexploitation for fuelwood and fodder, and shifting cultivation. Since 1975, extensive quarrying on the lower slopes of some areas has destroyed extensive areas of forest. As a result of loss of forest cover and undergrowth, erosion has become a serious problem. Especially in areas where road construction is taking place, there is overgrazing by livestock, and excessive fuelwood is collected. However, Chir pine forests are resilient and can tolerate considerable human pressure.

Justification of Ecoregion Delineation
Previous analyses of conservation units in the Indo-Malayan region by MacKinnon (1997) and for the Indian Himalaya by Rodgers and Panwar (1988) placed the Himalayan subtropical pine forests in conservation units that included the range of habitat types within the south-facing slopes of the Himalayas. In this analysis, we sought to represent the distinct ecosystems of regional extent in separate ecoregions. Therefore, we used MacKinnon's (1997) digital map of the distribution of original vegetation to delineate the boundaries of the subtropical pine forests that run the length of the Himalayan Mountain Range and place them in a separate ecoregion, the Himalayan Subtropical Pine Forests [IM0301]. All the Himalayan ecoregions are part of Udvardy's Himalayan highlands biogeographic province.

References
References for this ecoregion are currently consolidated in one document for the entire Indo-Pacific realm.
Indo-Pacific Reference List

Prepared by: Gopal S. Rawat and Eric D. Wikramanayake, with contributions from Pralad Yonzon
Reviewed by:

 

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