Andaman and Nicobar Islands rainforest ecoregion

Andaman and Nicobar Islands rainforest ecoregion
Name	Andaman and Nicobar Islands rainforest ecoregion
Biogeographic realm	Indomalayan realm
Biome	Tropical and subtropical moist broadleaf forests
Area km2	8300
Countries	India
States	Andaman Islands, Nicobar Islands
Conservation	Vulnerable

Andaman and Nicobar Islands rainforest ecoregion

The Andaman and Nicobar Islands rainforest ecoregion occupies the arc of islands in the Bay of Bengal and Andaman Sea between the Indian Ocean and the Malay Archipelago, forming a floristically rich and faunistically unique zone of the Indomalayan realm. Influenced by the Indian monsoon, the Bay of Bengal cyclone belt, and proximity to Sumatra and Myanmar, the ecoregion supports humid evergreen and seasonal forests that harbor numerous endemics and species shared with Southeast Asian rainforests. Its insular geography has made the islands a focus of biogeographic research linking the Wallace Line debate to Indian and Southeast Asian conservation agendas.

Geography and Climate

The ecoregion comprises the major island groups of the Andaman Islands and the Nicobar Islands, including principal islands such as North Andaman Island, Middle Andaman Island, South Andaman Island, Little Andaman, Great Nicobar, Car Nicobar, and Little Nicobar. Geologically, the islands are part of the Arakan Yoma uplift and associated with the Indian Plate–Burma Plate boundary; seismicity from the 2004 Indian Ocean earthquake and tsunami profoundly reshaped coastal habitats. Ocean currents influenced by the Equatorial Counter Current and seasonal shifts in the Southwest Monsoon and Northeast Monsoon produce annual rainfall gradients from 2,000 mm to over 3,000 mm, with humid tropical temperatures moderated by maritime winds near Port Blair and Campbell Bay. Elevations on islands such as Saddle Peak create orographic rainfall and microclimates that support montane fringe forests.

Flora and Vegetation Types

Vegetation ranges from coastal mangroves and littoral forest to lowland evergreen rainforest, semi-evergreen woodland, and montane stunted forest. Coastal zones feature species complexes including Rhizophora mangroves adjacent to casuarina-dominated stands introduced near Havelock Island. Lowland evergreen assemblages include canopy trees related to Dipterocarpaceae lineages, alongside genera such as Terminalia, Pterocarpus, Hopea, and Artocarpus. Understorey layers support palms like Caryota and climbers akin to those in the Sundaland region. Littoral and freshwater wetlands harbor Nypa fruticans and salt-tolerant flora that echo associations on Andaman Sea coasts. Vegetation mosaics on Great Nicobar show transitional affinities with Malay Peninsula floras and retain relic taxa documented in historical surveys by naturalists visiting the Bay of Bengal islands.

Fauna and Endemic Species

Faunal assemblages include endemic mammals, birds, reptiles, amphibians, and invertebrates shaped by island isolation. Notable mammals are the endemic Nicobar treeshrew and populations of Andaman wild pig and Long-tailed macaque that interact with human-modified habitats near Port Blair. Avifauna features endemics and near-endemics such as the Andaman woodpecker, Andaman scops owl, and Nicobar pigeon; migratory and resident species include links to Gulf of Mannar flyways. Herpetofauna includes endemic frogs and geckos with affinities to Sumatra and Myanmar clades described in museum collections of institutions like the Zoological Survey of India. Marine-adjacent fauna comprise coral reef assemblages connected to Andaman Sea biodiversity hotspots and support species exploited by fisheries around Little Andaman and Car Nicobar. Invertebrate endemism is high among mollusks, insects, and land snails recorded by collectors working with the Indian Museum and international partners.

Human Inhabitants and Indigenous Cultures

Human presence includes indigenous communities and later settlers; indigenous groups such as the Great Andamanese peoples, Onge, Jarawa, Sentinelese, and Nicobarese maintain distinct languages, material cultures, and subsistence patterns centered on foraging, fishing, and horticulture. Colonial encounters involving the British Empire and later administration by the Indian Government altered settlement distribution, introducing plantations, port infrastructure at Port Blair, and mission influences documented in colonial archives. Cultural landscapes feature traditional ecological knowledge about canoe construction, shellfish gathering, and uses of timber and non-timber forest products that inform contemporary ethnobiology research by scholars from institutions like Jawaharlal Nehru University and University of Cambridge.

Conservation Status and Threats

The ecoregion faces threats from deforestation for agriculture and plantations, coastal development near Neil Island and Havelock Island, invasive species, illegal logging, and the legacy impacts of the 2004 Indian Ocean earthquake and tsunami. Infrastructure expansion tied to strategic installations and ports has led to habitat fragmentation documented in environmental impact assessments for projects in Swaraj Dweep and Campbell Bay National Park buffer zones. Climate change and sea-level rise threaten low-lying atolls and estuarine mangroves, while unsustainable fisheries and coral bleaching events linked to warming have reduced reef resilience. Social tensions over land rights between indigenous communities and settler populations complicate conservation, prompting legal interventions under frameworks administered by the Ministry of Environment, Forest and Climate Change.

Protected Areas and Management Strategies

Protected areas include Rani Jhansi Marine National Park, Saddle Peak National Park, Campbell Bay National Park, and Great Nicobar Biosphere Reserve, managed under national legislation and collaborative programs with NGOs and research institutions. Management strategies emphasize integrated conservation and development, community-based forest management with indigenous participation, invasive species control, and marine protected area zoning around coral reefs. Post-tsunami restoration initiatives involved partnerships with the United Nations Development Programme and national agencies to restore mangroves and livelihood systems, while monitoring programs engage researchers from the Wildlife Institute of India and international conservationists. Effective conservation relies on reconciling infrastructure needs with protection of endemic species, strengthening legal recognition of tribal territories, and enhancing transboundary collaboration with Indonesia and Myanmar for regional biodiversity corridors.

Category:Ecoregions of India