Native Plants Alter Assam’s Dibru-Saikhowa Ecosystem
The riverine ecosystem of Dibru-Saikhowa National Park (DSNP) in eastern Assam is undergoing changes. A recent study reveals that native plants, along with invasive species, are transforming the park’s grassland landscape. DSNP is India’s only habitat for feral horses and a vital biodiversity hotspot. These changes threaten many endemic and endangered species.
Dibru-Saikhowa National Park
DSNP was formed by merging Dibru and Saikhowa Reserve Forests. It became a wildlife sanctuary in 1995 and a national park in 1999. The area covers about 425 square kilometres and lies between the Brahmaputra and Dibru rivers. UNESCO declared it a Biosphere Reserve in 1997. The park features grasslands, semi-evergreen forests, and wetlands, providing habitat for unique flora and fauna.
Key Findings on Vegetation Changes
The study analysed land use and land cover (LULC) changes from 1999 to 2024 using remote sensing and GIS technology. Grasslands covered 28.78% of the park in 2000 but declined sharply over two decades. Shrublands and degraded forests expanded, replacing grasslands and semi-evergreen forests. By 2024, degraded forests covered 23.47% of the area, rising from 10.87 sq km in 2013. This shift indicates a loss of open habitats vital for many species.
Role of Native and Invasive Plant Species
Native trees Bombax ceiba (Simalu) and Lagerstroemia speciosa (Ajar) are spreading into grasslands. These grassland invaders alter the ecosystem similarly to invasive species like Chromolaena odorata, Ageratum conyzoides, Parthenium hysterophorus, and Mikania micrantha. Both native and invasive plants reduce grassland area and change vegetation structure. This affects species dependent on open habitats.
Impact on Wildlife and Biodiversity
Grassland loss threatens species such as the Bengal florican, hog deer, and swamp grass babbler. These animals rely on open grasslands for survival and breeding. The park also houses about 200 feral horses, descendants of World War II military horses. Habitat changes may endanger their population and other native fauna. Forest degradation reduces biodiversity and carbon storage, potentially worsening climate change.
Anthropogenic Pressures and Flooding
Human activities from forest villages inside the park add pressure to the ecosystem. Recurring floods from the Brahmaputra River also influence landscape changes. These factors combined accelerate habitat degradation and complicate conservation efforts.
Recommendations for Conservation
The study suggests a targeted grassland recovery project. It includes controlling invasive species, enhancing park surveillance, increasing staff, and relocating forest villages to reduce human impact. Community-based conservation efforts are encouraged. Managing land use based on scientific data can protect habitat patches and improve survival chances for native species.
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