Dibru-Saikhowa National Park
Grassland invaders stifle Assam’s island-like national park
Context: A new study published in Earth journal has identified two native species — Bombax ceiba (Simalu) and Lagerstroemia speciosa (Ajar) — as “grassland invaders” in Dibru-Saikhowa National Park (DSNP), Assam.
About Dibru-Saikhowa National Park
Dibru-Saikhowa National Park (DSNP), located in the eastern part of Assam, is a unique protected area renowned for its rich biodiversity, distinctive riverine landscape, and as the only habitat of feral horses in India. Spread across 425 sq. km, it lies primarily in the Dibrugarh and Tinsukia districts and was declared a wildlife sanctuary in 1995, upgraded to a national park in 1999, and is also a UNESCO-designated Biosphere Reserve (1997).
- Geographical Landscape/Topography: DSNP lies at an elevation ranging from 110 to 126 meters above sea level. The Brahmaputra and Lohit Rivers define its boundaries to the north, the Dibru River to the south, the Dehing River to the east, and tea gardens and human settlements to the west. The park experiences a tropical monsoon climate, receiving heavy annual rainfall between 2,300–3,800 mm, which, along with frequent floods, plays a key role in shaping its unique floodplain ecosystem.
- Vegetation: The region features a mosaic of grasslands, wetlands, swamps, semi-evergreen forests, and riverine islands. However, recurring floods and increasing human pressures have accelerated ecological degradation in recent years.
- Rivers: Include the Brahmaputra in the north, the Dibru in the south, and the Lohit and Dehing in the east; together, they shape the park’s dynamic floodplain ecology and sustain its rich aquatic biodiversity.
- Flora includes trees like Bombax ceiba, Lagerstroemia parviflora, Dillenia indica, Mesua ferrea, grasses such as Imperata cylindrica, Phragmites karka, Saccharum ravennae, and diverse orchids (35 epiphytic, 8 terrestrial).
- Fauna comprises Bengal tiger, leopards, capped langur, Hoolock gibbon, Gangetic dolphin, wild buffalo, hog deer, and over 350 bird species including the Bengal florican, alongside 43 reptiles, 104 fish species, and 12 Schedule I mammals under the Wildlife Protection Act, 1972.
Feral Horse
Feral horses are free-roaming horses descended from domesticated stock. Though often called “wild,” they are not truly wild but have adapted to natural conditions over generations. Origin Theories:
- World War II Link: The most accepted theory is that they are descendants of horses used by Allied forces (British and American) against the Japanese, left behind after the war.
- Earthquake Factor (1950): The great Assam earthquake changed river courses, trapping many horses in Dibru-Saikhowa, where they adapted to chapori (sandbar) habitats.
