BharatNotes What is Tropical Evergreen Forests?
Tropical evergreen forests (also called tropical rainforests) are dense, lush forests of warm and humid tropical regions that stay green all year. Because rainfall and warmth are abundant and continuous, the trees have no fixed period for shedding leaves, flowering or fruiting — so different trees lose and renew their foliage at different times, and the forest never appears bare. In the Champion and Seth (1968) classification, the wettest variant — tropical wet evergreen forest — sits within Major Group I, the Moist Tropical Forests.
Climatic Conditions
These forests develop in areas with:
| Factor | Typical value |
|---|---|
| Annual rainfall | Above 200 cm (often 250 cm or more) |
| Mean annual temperature | Above 22°C |
| Relative humidity | Consistently high, above ~70% |
| Dry season | Very short or virtually absent |
The combination of heavy, well-distributed rain and uniform high temperature means there is no resting season for plant growth.
Key Features
- Multi-layered (stratified) structure — a tall top canopy with emergent trees, beneath which lie middle and lower tree layers, then shrubs and ground creepers, all competing for light.
- Great tree height — trees commonly rise to 30–45 m, and the tallest can reach 60 m or more.
- Dense, closed canopy — the interlocking crowns keep the forest floor shaded and damp, with limited undergrowth in the deepest shade.
- Hardwood timber species — rosewood, mahogany, ebony and ironwood, along with bamboos and canes.
Distribution in India
Tropical evergreen forests in India occur mainly on:
- the western (windward) slopes of the Western Ghats across Kerala, Karnataka, Tamil Nadu and Maharashtra;
- the hills of the north-eastern region (the Assam–Meghalaya belt); and
- the Andaman and Nicobar Islands, where maritime influence brings heavy rain with almost no dry spell.
Small isolated evergreen patches also survive in parts of Odisha.
Significance and UPSC Angle
These forests are biodiversity treasure-houses, sheltering species such as the lion-tailed macaque, Malabar civet, elephants, and hornbills (great Indian hornbill, Malabar grey hornbill). The Western Ghats evergreen belt is part of a globally recognised biodiversity hotspot, making these forests central to conservation debates.
For UPSC, the most-tested points are the rainfall threshold (above 200 cm), the evergreen-because-no-fixed-leaf-fall logic, the exact regions of occurrence, and the place of these forests within the Champion and Seth six-group framework. A frequent confusion to avoid: do not mix up tropical evergreen forests with tropical deciduous (monsoon) forests, which occur in the 70–200 cm rainfall belt and do shed leaves seasonally. Note also the distinction between wet evergreen and semi-evergreen forests — the latter form a transition zone between evergreen and deciduous types.
Data note: rainfall and temperature thresholds reflect standard NCERT and Champion & Seth (1968) classifications, which are structural definitions and not year-specific statistics.
