East Deccan dry evergreen forests
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The East Deccan dry evergreen forests are an ecoregion of southeastern India. The ecoregion includes the coastal region behind the Coromandel Coast on the Bay of Bengal, between the Eastern Ghats and the sea. It covers eastern Tamil Nadu state and southeastern Andhra Pradesh state.
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[edit] Setting
The East Deccan dry evergreen forests cover lie in the rain shadow of the Western Ghats and Eastern Ghats, which block the rain-bearing summer southwest monsoon. Rainfall averages 800 mm/year, and mostly falls during the highly variable northeast monsoon between October and December.
The ecoregion covers an area of 25,500 square kilometers (9,800 square miles), extending from Ramanathapuram District of Tamil Nadu to Nellore District of Andhra Pradesh. Much of the ecoregion is densely settled, and has been substantially altered by human activity, including agriculture, grazing, and forestry, over the centuries. The ecoregion is home to the metropolis of Chennai (Madras), and a number of other cities, including Pondicherry, Thanjavur, Kanchipuram and Nellore. It is estimated that 95% of the original forest cover has been cleared, and the species composition of the remaining forests have been altered by intensive human use.
Unlike most of the world's tropical and subtropical dry broadleaf forests, whose trees tend to lose their leaves during the dry season to conserve moisture, the East Deccan dry evergreen forests retain their leaves year round. Only two other ecoregions exhibit a similar pattern, the Sri Lanka dry-zone dry evergreen forests and the Southeastern Indochina dry evergreen forests.
The ecoregion is home to two important wetlands, Kaliveli Lake north of Pondicherry in Viluppuram District of Tamil Nadu, and Pulicat Lake north of Chennai. Kaliveli lake is the one of the largest wetlands in peninsular India, and is deemed a wetland of national and international importance by the IUCN. It is a seasonal wetland, with a gradient from freshwater to brackish water, and is an important feeding and breeding ground on migratory bird flyway. It is currently threatened by encroachment by agricultural fields, wildlife poaching, loss of the surrounding forests, and increases in commercial prawn farming.
[edit] Flora
The original vegetation of the ecoregion consisted of forests with an understory of evergreen trees and an emergent canopy of taller deciduous trees, including Sal (Shorea robusta), Albizia amara and Chloroxylon spp. Intensive human use of the forests over the centuries has mostly eliminated the deciduous canopy species, and the ecoregion's remaining forests are now characterized by areas of leathery-leaved evergreen forest, with a relatively low (10-meter) closed canopy. Predominant species are Manilkara hexandra, Mimusops elengi, ebony (Diospyros ebenum), Strychnine tree (Strychnos nux-vomica), Eugenia spp., Drypetes sepiaria, and Flacourtia indica. A few small enclaves of deciduous Sal forest exist, but are under intensive human pressure.
Only five percent of the ecoregion remains in forest, which is found in isolated pockets. Most of the ecoregion's forests have been degraded into tropical dry evergreen scrublands, characterized by thorny species such as Ziziphus glabarrima, Dicrostachys cinerea, Randia dumetorum, and Carissa spinarum.
[edit] Protected areas
Less than one percent of the ecoregion lies in reserves or protected areas. The Marakanam Reserve Forest, a sacred grove near Marakkanam, northwest of Pondicherry in Tamil Nadu, preserves a section of evergreen closed canopy forest. Several other temple groves in the surrounding area, including Puthupet, Pillaichavadi, Mudaliarchavadi, and Kottakarai, preserve small enclaves of forest. The Point Calimere Wildlife and Bird Sanctuary protects a 17.26 km². enclave of dry evergreen forest, as well as tidal wetlands and mangroves. Other preserves in the region include Vettangudi Bird Sanctuary (30 km²) in Sivaganga District of Tamil Nadu, and Nelapattu Bird Sanctuary (160 km²) on Pulicat Lake in Nellore District of Andhra Pradesh.
[edit] References
- Ramanujam, M.P. and Kadamban, D. Plant biodiversity of two tropical dry evergreen forests in the Pondicherry region of South India and the role of belief systems in their conservation. Biodiversity and Conservation, 10 (7): 1203-1217, July 2001
- Ramanujam M.P. and Praveen Kumar, Cyril K. Woody species diversity of four sacred groves in the Pondicherry region of South India. Biodiversity and Conservation, February 2003, vol. 12 no. 2, pp. 289-299(11)
- Blasco, F. and Legris, P. Dry Evergreen Forest of Calimere and Marakanam. Journal of the Bombay Natural History Society, Vol. 70 (2), August 1973, p. 278.
