India possesses significant tropical rainforest cover, hosting some of the most biologically diverse ecosystems on the planet. These forests are broadly classified as Tropical Evergreen Forests, characterized by dense, multi-layered canopies that remain green all year. Their existence is linked to India’s unique geography and the dynamics of the monsoon. These ecosystems play a significant part in maintaining biodiversity and regulating regional climate patterns.
What Qualifies as a Rainforest in India
The ecological criteria for a true rainforest in India, formally known as a Tropical Wet Evergreen Forest, include a specific climate profile. These regions must receive high annual rainfall, typically exceeding 2,000 millimeters, with a consistently warm temperature range between 25°C and 30°C. The defining characteristic is the absence of a prolonged dry season, allowing vegetation to thrive continuously throughout the year.
Tropical Semi-Evergreen Forests also exist and are often grouped under the general term “rainforest.” These transitional forests receive slightly less rainfall, usually between 1,500 and 2,000 millimeters, and experience a short, discernible dry period. While less dense than their wet evergreen counterparts, they share the trait of having many species that do not shed all their leaves simultaneously. Both types represent a high-rainfall, high-humidity ecosystem.
Geographic Distribution of Indian Rainforests
India’s rainforests are primarily concentrated in three distinct geographical areas, shaped by unique climatic and topographical factors. The Western Ghats mountain range, running parallel to the western coast of the Indian peninsula, is one of the most prominent regions. This area intercepts the southwest monsoon winds, causing heavy orographic rainfall along the western slopes and supporting extensive wet evergreen forests.
The Western Ghats are recognized as a biodiversity hotspot, where rainforests exist as a fragmented but dense cover across states like Kerala, Karnataka, and Maharashtra. Annual precipitation in the southern parts of the range often exceeds 2,800 millimeters. These forests vary with elevation, including montane rain forests in the higher reaches, such as the Nilgiri hills.
The second major area is the Northeastern Region, encompassing states like Assam, Arunachal Pradesh, Meghalaya, and Mizoram. Rainfall here is high, often surpassing 2,300 millimeters annually, contributing to a lush and dense forest cover. The region serves as a geographical gateway for much of India’s flora and fauna, resulting in a high diversity of forest types, including both evergreen and semi-evergreen.
The Andaman and Nicobar Islands host a unique type of tropical wet evergreen forest, shaped by their isolated island ecosystem. The archipelago’s location ensures consistent rainfall and high humidity, supporting tall, dense evergreen forests and specialized littoral and swamp forest types. The isolation of these islands has led to the evolution of species found nowhere else.
Endemic Flora and Fauna
The Indian rainforests are known for their biological wealth and high level of endemism—species native and restricted to these regions. The Western Ghats alone harbor approximately 1,500 endemic plant species. The Neelakurinji flower, which blankets the hillsides of the Western Ghats once every twelve years, is a famous floral example.
Among the fauna, the Purple Frog (or Pig-nosed Frog) is a striking example of amphibian endemism. This burrowing species spends most of its life underground, surfacing only briefly for mating during the monsoon. The Lion-tailed Macaque, a primate with a distinctive silver mane, is another threatened mammal endemic to the southern Western Ghats.
The Andaman and Nicobar Islands also demonstrate unique endemism, exemplified by the Nicobar pigeon, a bird found only within the archipelago. The Namdapha flying squirrel is an endemic mammal from the Northeastern rainforests of Arunachal Pradesh. This biological uniqueness underscores the importance of India’s rainforests as genetic reservoirs.