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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.

However, overexploitation of this species and habitat degradation has restricted the species in some protected or virgin forest patches only. There has been a notable reduction of about 50 to 70% of the population in the last 300 years. Due to rampant population decline, it has been driven to the edge of extinction and IUCN (International Union for Conservation of Nature) listed it as Endangered species on The IUCN Red List of Threatened Species. This species was also declared as the State Tree by Assam and Arunachal Pradesh Governments to revive the threatened species and protect their natural habitats.

In the context of Assam, some protected areas like Dehing Patkai Wildlife Sanctuary, Hollongpar Gibbon Wildlife Sanctuary are one of the natural habitats of the Hollong tree. However, these regions are under threat of opencast mining of coal (particularly in Dehing Patkai), illegal felling, and extension of monoculture agricultural practices that may lead to the disappearance of the species in near future. In addition to this important species being threatened by anthropogenic activities, N. Senthilkumar and N. Barthakur (2009) reported nine species of insect pests from Assam that arouses mortality of seedling of Hollong. Also, reduction or shifting of temperature and rainfall patterns can alter the normal phenological cycle of this species which could exacerbate the problem to their survivability in the future.

Hollongapar Gibbon Wildlife Sanctuary, Assam with Hollong trees

Photo: Udayan Borthakur

Thus, there is a need for scientific evaluation of the distribution of possible habitats of this species. It is also necessary to assess the socio-perspective of local communities who are residing in respective forest areas. Government, non-government agencies, institutions, etc. should promote awareness among common people and introduce community-based conservation action plans which include grass-root activities that bring local community, Governmental departments, and other organizations to work together in a common platform towards achieving conservation of Hollong.


The author is thankful to Dr. Arun Jyoti Nath, Department of Ecology and Environmental Science, Assam University Silchar, for his valuable suggestions and help.

About the Author:

Animekh Hazarika is a Researcher at Department of Ecology and Environmental Science, Assam University, Silchar.

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