Guwahati, July 12 -- Over the past three decades, the spread of 14 invasive plant species has emerged as a key driver behind the loss of more than 43% of the grasslands in Assam's Manas Tiger Reserve, threatening vital habitat for the greater one-horned rhinoceros, pygmy hog, hispid hare and several other rare wildlife species.

Data from the Forest Department under the Bodoland Territorial Council (BTC) show that grassland cover in the 2,837.31 sq km Manas Tiger Reserve declined from 53.61% in 1990 to 30.24% in 2019. This represents a relative loss of 43.59% and an absolute reduction of 23.37% in grassland area over the period.

The reserve, which shares an international boundary with Bhutan's Royal Manas National Park, is one of India's...