Guwahati: The vast floodplain grasslands that define Kaziranga and Manas, Assam’s two UNESCO World Heritage Sites, are disappearing at an alarming pace, raising fresh concerns among conservationists, forest officials and wildlife experts.
Adding to the concern, the Act Implementation Committee of the Assam Legislative Assembly has alleged that UNESCO has failed to respond despite being formally approached for technical support to restore the rapidly degrading grassland ecosystems.
“UNESCO is a white elephant. We submitted a report to them in 2024. But there is no response,” said Khumtai MLA and Committee chairman Mrinal Saikia.
In a letter addressed to the Director-General of UNESCO on December 5, 2024, the Committee said it had observed “with deep concern” the rapid degradation of the grassland ecosystems in Manas National Park and Tiger Reserve, warning that the decline poses a serious threat to biodiversity and the Outstanding Universal Value (OUV) of the World Heritage Site.
Following an official visit to Manas and discussions with the Forest Department, the Committee noted that nearly 60 per cent of the Manas Tiger Reserve was covered by grasslands during the 1980s. Today, only about 30 per cent remains functional grassland habitat, affecting large herbivores such as elephants, one-horned rhinos and swamp deer.
According to Saikia, the degradation is being driven largely by the spread of woody species such as Bombax ceiba and Dillenia pentagyna. The surviving grasslands are also under increasing pressure from invasive plants, including Mikania micrantha, Chromolaena odorata, Lantana camara and Leea species, which suppress native grasses and accelerate habitat loss.
“Despite commendable efforts by frontline staff, limited resources and technical capabilities are significantly hindering the execution of large-scale grassland revival programmes,” Saikia said.
The Committee warned that continued loss of grassland habitat could severely affect several endangered species, including the eastern swamp deer, pygmy hog, Bengal florican, one-horned rhinoceros, Asian elephant and Royal Bengal tiger, all of which contribute to the global conservation significance of Manas.
It sought UNESCO’s technical guidance for preparing a comprehensive grassland restoration and management strategy for the reserve. The Committee also requested support for satellite-based vegetation monitoring, invasive species mapping, access to international conservation funding and capacity-building programmes for frontline staff in grassland restoration, invasive species control and scientific fire management.
“Seven months have passed since submitting the letter, but there has been no response from UNESCO,” Saikia said.
The issue comes at a time when both Kaziranga and Manas continue to report encouraging populations of rhinos, tigers and elephants. However, the floodplain grasslands that sustain these flagship species continue to shrink year after year.
Field studies conducted over the past four decades indicate that Assam has lost nearly 70 per cent of its grasslands. Kaziranga, where wet alluvial grasslands cover nearly two-thirds of the park, is among the worst-affected landscapes.
The situation is even more serious in Manas. A World Heritage Committee report, prepared as part of the State of Conservation assessment ahead of UNESCO’s 48th session in Busan this month, states that nearly half of the park’s grassland ecosystem has now been overtaken by invasive plant species, threatening its long-term ecological health.
The report notes that this represents a sharp deterioration since a 2014-2018 assessment, which found only 20 per cent of the grasslands to be severely affected. In less than a decade, the extent of degradation has more than doubled.
According to a Landsat-based study by Kushwaha and Madhavan Unni (1986), grasslands covered about 52 per cent of Kaziranga, including 41 per cent tall grass and 11 per cent short grass. Open jungle accounted for 29 per cent, followed by water bodies (8 per cent), sand (6 per cent) and swamps (4 per cent).
Kaziranga National Park and Tiger Reserve has 19 grass species. The dominant tall grasses include Imperata cylindrica, Erianthus species, Phragmites karka, Saccharum spontaneum, Pennisetum purpureum (elephant grass) and Vetiveria zizanioides. Common shorter grasses include Paspalum, Echinochloa, Eragrostis, Themeda villosa and Oplismenus compositus.
A 2023 Gauhati University study, published through Krishi Jagran, used a Cellular Automata-Markov model to project that grasslands and agricultural land in the region will expand by 2050, while forest cover, water bodies and sandbars are likely to shrink.
A retired IFS officer said Assam has lost nearly 70 per cent of its grasslands over the past four decades. However, this is a state-level figure and does not apply specifically to Kaziranga.
Assam Environment and Forest Minister Jayanta Malla Baruah acknowledged the problem, saying the ecological balance between woodland and grassland has steadily shifted over the decades.
“The ideal ecological balance is an equal ratio of woodland and grassland. In 1970, woodland covered around 370 sq km, while grassland covered 440 sq km. Over the decades, woodland has expanded and grassland has steadily declined. Today, grassland has fallen to below 30 per cent,” the minister said.
Baruah said restoring the ecological balance of Manas National Park remains one of the Forest Department’s top priorities.
He attributed the decline to multiple factors, including infrastructure development in neighbouring Bhutan, construction of embankments, past civil unrest in the region and the spread of invasive plant species.
The minister said the department has initiated several restoration measures.
“Between 2022 and 2025, around 609 hectares of degraded grassland were restored under the APFPC French-funded project. Similar restoration efforts have also been undertaken through the Pygmy Hog Conservation Programme and other initiatives,” he said.
Saikia cautioned that shrinking grasslands ultimately reduce grazing areas, leading to declining herbivore populations and increasing pressure on predators. He said the impact is already visible in species such as the critically endangered Bengal florican, whose global population has dropped below 1,000, with Manas and Kaziranga remaining among its last strongholds.
Senior IFS officer and Manas Field Director Sonali Ghosh said Assam’s grasslands are ecologically unique.
“Grasslands are vital ecosystems and even more relevant for Assam, which has unique sub-Himalayan alluvial grasslands in Manas and floodplain grass assemblages in Kaziranga. They support unique faunal elements found nowhere else now,” she said.
She noted that nearly one-third of Manas’s 500 sq km core area was open grassland four decades ago, but by 2019 nearly half of that habitat had been lost to expanding woodland and invasive weeds.
“A 50 per cent reduction in grasslands is very worrying and without restoration, sustaining current wildlife populations will become difficult,” she said.
Conservation scientist Alolika Sinha stressed that grasslands are as critical as forests for biodiversity and human well-being.
“Grasslands are vital ecosystems that support lives and livelihoods. However, their spatial decline and degradation in high conservation value landscapes such as Manas threaten grassland-obligate species and undermine the well-being of people. The need of the hour is a comprehensive, science-based conservation strategy that integrates habitat restoration, invasive species management and long-term ecological monitoring,” she said.
She added that ecosystem restoration is often associated with planting trees, while grasslands receive far less attention.
“Restoring native grasses is just as important for biodiversity conservation, strengthening climate resilience and ensuring people’s well-being. We need strong, dedicated policies and sustained investment of resources to secure our grasslands,” Sinha said.
Kaziranga Field Director C. Ramesh has also highlighted the growing threat from invasive herbs and weeds, including several aquatic species that are steadily replacing native fodder grasses.
Hydrological changes linked to Bhutan have added another challenge. Manas lies downstream of the Kurichu dam, while rivers such as the Beki and Manas frequently bring flash floods into the park during the monsoon, inundating large areas and breaching embankments near Panchmile under the Bansbari Range.
Although annual floods naturally rejuvenate the Brahmaputra floodplain grasslands, sudden releases of water from across the border have repeatedly caused extensive damage to roads, bridges and grassland habitats.
Encroachment remains another major concern. The Assam government has intensified eviction drives in reserve forests surrounding both Kaziranga and Manas.
Chief Minister Himanta Biswa Sarma, while welcoming the Supreme Court’s order in February upholding the state’s eviction mechanism, said 1,25,326 hectares of forest land had already been cleared of encroachment. He added that the court had permitted the state to proceed against another 3,62,082 hectares, saying the order would help protect Kaziranga, Manas, Pobitora and other forest areas.
UNESCO, in its State of Conservation assessment, noted that there had been no fresh agricultural encroachment inside the core World Heritage property of Manas. However, it observed that older encroachments remain unresolved because of the social and political sensitivities surrounding indigenous communities living in the area.
The grasslands form the ecological foundation of both parks. One-horned rhinos, wild water buffaloes, swamp deer, hog deer and the pygmy hog all depend on a mosaic of short and tall grasses for food, shelter and breeding habitat, making the health of these ecosystems critical to the survival of Assam’s iconic wildlife.