Location and General Description
The ecoregion represents the dry deciduous forests on the Chhota-Nagpur Plateau and lies between the moist deciduous forests of the Eastern Ghats and Satpura Range and of the lower reaches of the Gangetic Plains. It extends across the eastern Indian states of Bihar, Madhya Pradesh, and West Bengal.
The Gondwana substrates attest to the plateau's ancient origin. It is part of the Deccan Plate, which broke free from the southern continent during the Cretaceous to embark on a 50-million-year journey that was violently interrupted by the northern Eurasian continent. The northeastern part of the Deccan Plateau, where this ecoregion sits, was the first area of contact with Eurasia.
The plateau receives less rainfall than the adjacent ecoregions that support moist deciduous forests. Therefore, the vegetation is drier than in the adjacent ecoregions. The dry deciduous forests typically are composed of three stories, with an upper canopy reaching 15-25 m, a high understory at 10-15 m, and an undergrowth at about 3-5 m. The vegetation is characterized by Shorea robusta, usually in association with Anogeissus latifolia, Terminalia alata, Lagerstroemia parviflora, Pterocarpus marsupium, Aegle marmelos, Syzygium operculatum, Symplocus racemosa, and Croton oblongifolius (Puri et al. 1989; Davis et al. 1995). Lianas are common in denser forests.
A dry deciduous scrub that grows to about 3-6 m in height is a common habitat type in this ecoregion. This scrub includes bamboo and shrubs such as Holarrhena and Dodonaea (Puri et al. 1989). At higher altitudes, there are shola-type forests characterized by Phoenix robusta, Pterospermum acerifolium, and Clematis nutans (WWF and IUCN 1995). The ecoregion also includes patches of moist deciduous forests and swampy areas, with several interesting plant species (Syzygium cumini, Manilkara hexandra, Ficus spp., Mallotus philippinensus) that are typical of moist deciduous forests.
Although Aglaia haselettiana, Carum villosum, and Pycnocyclea glauca are endemic, endangered plant species in this ecoregion, Diospyros melanoxylon, Madhuca longifolia, Butea monosperma, and Shleichera oleosa, are more economically useful species.
The ecoregion's fauna is neither exceptionally species-rich nor distinctive. The ecoregion's mammal fauna includes seventy-seven species, but none are endemic to it. Nevertheless, several of India's large charismatic vertebrates, including several that are threatened such as the tiger, Asian elephant, wild dog (Cuon alpinus), sloth bear (Melursus ursinus), chousingha (Tetracerus quadricornis), blackbuck (Antilope cervicapra), and chinkara (Gazella bennettii) (IUCN 2000), are found here. Importantly, unlike in many other ecoregions in this bioregion, there still are large areas of habitat capable of supporting viable populations of these species. These habitat blocks are included in two Level I TCUs (Dinerstein et al. 1997) that extend into the ecoregion.
There are almost 280 bird species, but none are endemic to the ecoregion. However, it harbors several species that are of conservation importance, including the globally threatened lesser florican (Eupodotis indica). Some of the hornbills, notably the Indian grey hornbill (Ocyceros birostris) and Oriental pied-hornbill (Anthracoceros albirostris), which need mature trees for nesting, should be focal species for conservation management.
More than half of the natural forests in this ecoregion have been cleared; however, extensive areas of intact forest remain in the northern areas. The thirteen protected areas in the ecoregion cover more than 6,700 km2, representing about 6 percent of the ecoregion (table 1). The average size of a protected area exceeds 500 km2, and two-Sanjay and Palamau-are larger than 1,000 km2. These large protected areas provide the essential core areas for the large vertebrates in this ecoregion. However, these reserves must be included in larger conservation landscapes for more effective long-term conservation of these species (Wikramanayake et al. 1999).
Table 1. WCMC (1997) Protected Areas That Overlap with the Ecoregion.
Protected Area Area (km2) IUCN Category
Sanjay [IM0207] 1,020 II
Lawalang 410 IV
Koderma 180 IV
Hazaribagh 450 IV
Palamau 1,330 II
Topchanchi 40 IV
Ramnabagan 150 IV
Dalma 630 IV
North Simlipal 420 II
Bhimbandh 910 IV
Gautam Budha [IM0120] 110 IV
Tamor Pingla 600 IV
Semarsot 470 IV
Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.
Types and Severity of Threats
Like many of the other ecoregions in this bioregion, livestock grazing has greatly affected the vegetation (Puri et al. 1989). However, extensive areas that are being mined for iron ore and open-pit coal mines pose very significant threats to the habitat, especially to critical migration paths of elephants and dispersal routes for tigers.
Justification of Ecoregion Delineation
In a previous analysis of conservation units, Rodgers and Panwar (1988), and subsequently MacKinnon (1997), divided the Deccan Peninsula into five biotic provinces and sub-biounits, respectively. But each of these units contains several vegetation types that extend over large areas. In this analysis, we represent these large ecosystems in separate ecoregions (in keeping with our definition of an ecoregion as an ecosystem of regional extent). Therefore, we modified the boundaries of Rodgers and Panwar's biotic province 6D (which is the same as MacKinnon's sub-biounit 16b) to include only the large expanse of dry deciduous forest in the Chhota-Nagpur Dry Deciduous Forests [IM0203]. We used MacKinnon's (1997) digital map of the original vegetation to define the boundaries of this ecoregion.
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