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Upper Gangetic Plains moist deciduous forests

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Tricarinate hill turtle (Melanochelys tricarinata), Uttar Pradesh, India (Photograph by © Persica/Abi Tamim)

Many years ago, the Upper Gangetic Plains Moist Deciduous Forests harbored impressive populations of tiger (Panthera tigris), greater-one horned rhinoceros (Rhinoceros unicornis), Asian elephants (Elephas maximus), gaur (Bos gaurus), and swamp deer (Cervus duvaucelli), to name but a few of the large vertebrates that used to roam here. Large hornbills made daily migrations from their feeding areas to mature groves, where they nested in cavities of tall trees and roosted for the night. Today, this natural biodiversity has been replaced by one of the densest human populations on Earth, and the fertile alluvial plains have been cleared and intensely cultivated.

caption Nawabganj Bird Sactuary, near Lucknow, Uttar Pradesh, India (Photograph by www.upportal.com)

There is so little natural forest left, it is difficult even to assign a particular vegetation type to it with any certainty. The small patches of forests that are left suggest that much of the upper Gangetic Plains may have supported a tropical moist deciduous forest with sal (Shorea robusta) as a climax species.

Location and General Description

This ecoregion lies along one of Asia's largest rivers, the Ganges. Originating in the western Himalayas, the river flows east along most of the length of the long mountain range to eventually join with the Brahmaputra River and head south to the Bay of Bengal. This ecoregion extends through the upper reaches of the Ganges River, across the northern Indian states of Uttar Pradesh, Haryana, and Bihar.

caption Source: WWF

The southwest monsoon originating in the Bay of Bengal provides the ecoregion's precipitation. Therefore, the eastern reaches receive more moisture, with a gradual trend towards drier conditions as one goes west. Annual rainfall averages less than 500 millimeters (mm). Topographically, the ecoregion has little relief except for floodplain scarps and ravines carved out by gully erosion. The substrate consists of deep alluvial soils deposited over the eons by the Ganges River.

The original moist deciduous habitat probably was dominated by Shorea robusta that formed a top canopy reaching 25-35 meters (m). Other associated species included Terminalia tomentosa, Terminalia belerica, Lagerstroemia parviflora, Adina cordifolia, Dillenia pentagyna, Stereospermum suaveolens, and Ficus spp. Patches of mesophilous grasslands, or savanna ecosystems, with Saccharum spontaneum, Saccharum narenga, Saccharum benghalense, and Vetiveria zizanioides intersperse the forest lands, representing early seral stages maintained by fire, flood, and grazing by domestic livestock.

Biodiversity Features

Several centuries ago, when the habitat was intact, this ecoregion harbored a rich wildlife community that included tiger, greater one-horned rhinoceros, Asian elephant, wild water buffalo, swamp deer, sloth bear (Melursus ursinus), and several hornbill species. Many of these space-dependent species are gone from much of the ecoregion, victims of the relentless wave of habitat destruction that has swept through most of the ecoregion.

caption Black-necked stork (Ephippiorhynchus asiaticus asiaticus), India (Photograph by Tony Coatsworth)

The seventy-nine known mammal species do not include any ecoregional endemic species. But there are some threatened mammals, including the tiger, Asian elephant, sloth bear, chousingha (Tetracerus quadricornis), and possibly small refuge populations of swamp deer in some habitat patches. With the exception of a few forested landscapes along the Himalayan foothills, habitat fragmentation is too far advanced throughout much of the ecoregion to support viable populations of the larger predators and herbivores such as tigers and Asian elephants that used to be common here. Nevertheless, the intact habitat landscapes and the protected areas within these forest fragments have been included in a high-priority (Level I) Tiger Conservation Units (TCU) that extends into the adjacent ecoregions to the north.

The bird fauna consists of about 290 species. There are no ecoregional endemic species, although the Indian bustard (Ardeotis nigriceps) and lesser florican (Eupodotis indica) are globally threatened species. The Indian grey hornbill (Ocyceros birostris) and Oriental pied-hornbill (Anthracoceros albirostris) need mature habitat for nesting and can be used as focal species for conservation management.

The Ganges River supports a population of freshwater dolphins (Platanista gangetica), and the associated wetlands support a rich and diverse waterfowl community that includes many migrant bird species as well as the mugger crocodile (Crocodylus palustris) and Gangetic gharial (Gavialis gangeticus).

Current Status

More than 95 percent of this vast ecoregion has been degraded or converted into agriculture and settlement areas by the dense human population that has settled here for thousands of years. Only one large block of habitat now remains, running along the Himalayan foothills in Uttar Pradesh and including Rajaji, Corbett, and Dudwa national parks.

The nine protected areas cover only 2,050 square kilometers (km2), amounting to less than 1 percent of the ecoregion area (Table 1). Among these, Rajaji and Corbett are important tiger reserves. Whereas Rajaji is the largest reserve completely within the ecoregion, Corbett (1,300 km2) is a larger reserve that also extends into the adjacent ecoregion. None of the other reserves are more than 300 km2 in extent, and the average size of the protected areas represented within this ecoregion is only 227 km2.

Table 1. WCMC (1997) Protected Areas That Overlap with the Ecoregion.

Protected Area

Area (km2)

IUCN Category

Corbett [IM0301]

260

II

National Chambal [IM0206]

130

PRO

Rajaji

790

II

Hastinapur

20

IV

Karera Great Indian Bustard

200

IV

Ranipur

230

IV

Ken Gharial

80

IV

Kishanpur

70

IV

Sohagabarwa [IM0115]

270

IV

Total

2,050

 

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

Nevertheless, the landscape that extends from Rajaji National Park to Corbett National Park is one of the most important conservation areas for tigers and elephants. This area is believed to have about 750 elephants and about 140 tigers. With the inclusion of Corbett National Park and Sonanadi Wildlife Sanctuary in Rajaji National Park, this potential conservation landscape can be as large as 2,500 km2.

Types and Severity of Threats

Impacts from human activities have devastated the natural habitat in this river plain for many years and continue to threaten the small patches of remaining forests and the biodiversity within them. Rodgers and Panwar, subsequently updated by Rodgers et al., have highlighted the conservation gaps in this region with specific proposals for additional protection.

But habitat fragmentation continues unabated, severing important habitat links that permit movements of large mammals such as elephants and tigers across the landscape and between protected areas. Road construction erodes the steep, fragile slopes and is invariably followed by human settlements because of the easier access. Grazing of cattle and other livestock is widespread. The threats to the Chila-Motichur corridor, critical for maintaining genetic exchange among elephants and tigers within their range in northwestern India, exemplifies the prevalent widespread threats. The habitat within this corridor has been degraded by settlements, overgrazing by domestic livestock, and invasions by exotic weeds.

Justification of Ecoregion Delineation

In a previous analysis, Rodgers and Panwar identified conservation units in India and placed the moist deciduous forests along the upper Gangetic valley in the Upper Gangetic Plains biotic province (7A). We retained this unit and represented it with the Upper Gangetic Plains Moist Deciduous Forests. The Upper Gangetic Plains Moist Deciduous Forests lie within Udvardy's Indus-Ganges monsoon forest 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. (2014). Upper Gangetic Plains moist deciduous forests. Retrieved from http://www.eoearth.org/view/article/51cbef217896bb431f69c937

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