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South Western Ghats montane rain forests

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South Western Ghats montane rain forests
Ecoregion territory (in purple)
Ecology
RealmIndomalayan
BiomeTropical and subtropical moist broadleaf forests
Borders
Geography
Area22,545 km2 (8,705 sq mi)
CountryIndia
States
Conservation
Conservation statuscritical/endangered[1]
Protected5,998 km²%[2]

The South Western Ghats montane rain forests is an ecoregion in South India, covering the southern portion of the Western Ghats in Kerala and Tamil Nadu at elevations from 1,000 to 2,695 m (3,281 to 8,842 ft). Annual rainfall in this ecoregion exceeds 2,800 mm (110 in).[3]

Setting

The ecoregion is the most species rich in peninsular India, and is home to numerous endemic species. It covers an area of 22,600 square kilometers (8,700 sq mi). It is estimated that two-thirds of the original forests have been cleared, and only 3,200 square kilometers, or 15% of the intact area, is protected.

The southern portion of the Western Ghats contains the highest peaks in the range, notably Anamudi in Kerala, at 2695 meters elevation. The Ghats intercept the moisture-laden monsoon winds off the Arabian Sea, and the average annual precipitation exceeds 2,800 mm. The northeast monsoon from October to November supplements the June to September southwest monsoon. The South Western Ghats are the wettest portion of peninsular India, and are surrounded by drier ecoregions to the east and north.[3]

Protected areas

In 1997, this ecoregion encompassed 13 protected areas with an area of 3,250 km2 (1,250 sq mi).[3] As of 2017, the total size of protected areas within this biome amounted to 5,998 km2 (2,316 sq mi), equivalent to 27% of the biome's extent. Another 62% is forested but outside protected areas.[2] Several of the protected areas in the northern portion are included within the Nilgiri Biosphere Reserve, and the Agasthyamala Biosphere Reserve covers the southern portion.

Flora

Satyrium nepalense in Silent Valley National Park

The cool and moist climate, high rainfall, and variety of microclimates brought about by differences in elevation and exposure supports lush and diverse forests; 35% of the plant species are endemic to the ecoregion. Moist evergreen montane forests are the predominant habitat type. The montane evergreen forests support a great diversity of species ( Animals and plants ). The trees generally form a canopy at 15 to 20 m, and the forests are multistoried and rich in epiphytes, especially orchids. Characteristic canopy trees are Cullenia exarillata, Mesua ferrea, Palaquium ellipticum, Gluta travancorica, and Nageia wallichiana. Nageia is a podocarp conifer with origins in the ancient supercontinent of Gondwana, of which India was formerly part, and a number of other plants in the ecoregion have Gondwana origins. Other evergreen tree species of the montane forest include Calophyllum austroindicum, Garcinia rubro-echinata, Garcinia travancorica, Diospyros barberi, Memecylon subramanii, Memecylon gracile, Goniothalamus rhynchantherus, and Vernonia travancorica.[3]

The other major habitat type in the ecoregion is the shola-grassland complex, found at elevations of 1,900 to 2,220 m. Shola is a stunted forest, with an upper story of small trees, generally Pygeum gardneri, Schefflera racemosa, Linociera ramiflora, Syzygium spp., Rhododendron nilgiricum, Mahonia napaulensis, Elaeocarpus recurvatus, Ilex denticulata, Michelia nilagirica, Actinodaphne bourdillonii, and Litsea wightiana. Below the upper story is a low understory and a dense shrub layer. These shola forests are interspersed with montane grasslands, characterized by frost- and fire-resistant grass species like Chrysopogon zeylanicus, Cymbopogon flexuosus, Arundinella ciliata, Arundinella mesophylla, Arundinella tuberculata, Themeda tremula, and Sehima nervosum.[3]

Fauna

The ecoregion supports India's largest elephant population, along with populations of threatened tiger (Panthera tigris), leopard (Panthera pardus), sloth bear (Melursus ursinus), gaur (Bos gaurus), and dhole or Indian wild dog (Cuon alpinus). The rare and endemic Nilgiri tahr (Nilgiritragus hylocrius) is limited to a 400 km band of shola-grassland mosaic, from the Nilgiri Hills in the north to the Agasthyamalai (Ashambu) Hills in the south. The lion-tailed macaque (Macaca silenus) and Nilgiri langur (Semnopithecus johnii) are endangered endemic primate species.[3]

90 of India's 484 reptile species are endemic to the ecoregion, with eight endemic genera (Brachyophidium, Dravidogecko, Melanophidium, Plectrurus, Ristella, Salea, Teretrurus, and Xylophis). Almost 50% of India's 206 amphibian species are endemic to the ecoregion, with six endemic genera (Indotyphlus, Melanobatrachus, Nannobatrachus, Nyctibatrachus, Ranixalus, and Uraeotyphlus).[3]

References

  1. ^ "South Western Ghats montane rain forests". Terrestrial Ecoregions. World Wildlife Fund.
  2. ^ a b Dinerstein, E.; Olson, D.; Joshi, A.; Vynne, C.; Burgess, N.D.; Wikramanayake, E.; Hahn, N.; Palminteri, S.; Hedao, P.; Noss, R. & al. (2017). "An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm". BioScience. 67 (6): 534–545. doi:10.1093/biosci/bix014.
  3. ^ a b c d e f g Wikramanayake, E.; Dinerstein, E. & Loucks, C.J. (2002). "South Western Ghats montane rain forests". Terrestrial Ecoregions of the Indo-Pacific: a Conservation Assessment. Washington, DC: Island Press. p. 284–287. ISBN 978-1559-639-23-1.