Hollong: The Forgotten Tree

by Animekh Hazarika

"Hey, my name is Hollong

My whole family sustained tropical biodiversity since time immemorial

Still I am facing rampant degradation from human greed

Please save me to promote human wellbeing and nature conservancy"

Dipterocarpus retusus Blume popularly known as Hollong belongs to family Dipterocarpaceae, is one of the important tree species of tropical rain forests. The species is distributed in northeast India including Cambodia, China, Indonesia, Laos, Malaysia Myanmar, Thailand, and Vietnam. In northeast, it is distributed in the alluvial deposits of Brahmaputra valley in the states of Assam (Upper Assam), Arunachal Pradesh, and Nagaland.

A Hollong tree

Photo: Udayan Borthakur

Hollong can be found at elevations from 100 - 1,300 meters. It grows best in areas where annual temperatures ranges between 22 - 30°C and with a mean annual rainfall of 3000 mm. This large tree species can grow up to 45 m tall and trunk can extend up to 3.5 – 6 m in diameter at breast height (DBH). The bark is brown. The straight, cylindrical bole can be free of branches for 15 - 20 m with a small spherical crown when mature. Leaves ovate to elliptic or oblong, glabrous above, glabrous or fasciculate pubescent on the venation beneath; lateral nerves numerous, parallel, prominent beneath. Flowers are usually solitary and fruits ovoid-shaped with enlarged wing-like calyx lobes.

Worldwide tropical forests are the sink of nearly 40% of terrestrial organic carbon storage and play a fundamental role in the global carbon cycle. Studies suggest the Dipterocarpus dominated forests have immense potential in storing terrestrial carbon besides its domestic uses and other economic benefits. The valuable medium hardwood is used in the construction of houses, internal construction work, and is the most suitable species for the plywood industry. The indigenous community in northeast India uses the Hollong for fuelwood, insect repellent, and extracting oleoresins which can be used as a lubricant. It is also considered as a sacred tree by the different indigenous communities.