Severe ecological disruption hits Sri Lanka’s UNESCO-listed biodiversity hotspot as experts assess long-term habitat loss and invasive spread after the 28 November storm.
Cyclone Ditwah takes heavy toll on Sri Lanka’s biodiversity
Cyclone Ditwah struck Sri Lanka on 28 November 2025, bringing torrential rains that triggered widespread floods and landslides. The Central Highlands bore the heaviest ecological toll. The National Building Research Organisation recorded 1,991 landslides nationwide, with 1,223 occurring in this region. These events uprooted forests, buried vegetation, and choked streams in biodiversity-rich zones.
The Disaster Management Centre reported at least 640 deaths and 221 people missing, with the highest casualties in the Central Highlands. Relief efforts prioritised human safety, but preliminary field observations reveal extensive environmental damage in remote areas.
Knuckles Mountain Range Cyclone Devastation
The Knuckles Mountain Range, a UNESCO World Heritage site, suffered major landslides. One earthslip in Yahangala reached depths of extreme severity and widths nearing 152 metres, according to assessments by Rainforest Protectors of Sri Lanka.
Jayantha Wijesingha, convener of Rainforest Protectors of Sri Lanka, said: “The depth of the landslide path is extremely deep, and in some places the width is nearly 500 feet. It will take some time to study and assess the scale of destruction.”
Canopy trees were uprooted. Understory vegetation was buried. Streams filled with sediment. These changes disrupted habitats for endemic plants, amphibians, and mammals unique to the area.
Sri Lanka Highlands Biodiversity Damage
The Central Highlands host Sri Lanka’s highest levels of endemism. Cyclone Ditwah exposed vulnerable slopes through topsoil loss and habitat fragmentation.
Suranjan Fernando, independent field biologist, stated: “Unlike infrastructure and housing, ecosystems are not built into our disaster valuation frameworks. The mountain regions are highly sensitive ecosystems. They need clear zoning, ecological assessments and legally enforced land use rules.”
Unplanned development on unstable slopes worsened impacts. Illegal constructions within river reservations collapsed under floodwaters.
Cyclone Ditwah Biodiversity Threats from Invasives
Floodwaters spread seeds of invasive species. Dense Himalayan knotweed growth contributed to slope failures under saturated conditions.
Rajika Gamage, environmental researcher, noted: “In several areas where landslides occurred, dense growth of Himalayan knotweed failed under the weight of rain-soaked vegetation. Floodwaters will spread their seeds over large areas. The hill country could soon experience an influx of invasive species.”
Cyclone Ditwah Environmental Impact on Recovery
A 2022 Asian Development Bank report warned of elevated landslide risks in the Central Highlands due to changing rainfall patterns. Those risks have now materialised.
Pradeep Samarawickrama, independent researcher, said: “Access roads to the remote areas are still blocked, so we have yet to conduct a full assessment of the situation. But the devastation is evident.”
Siril Wijesundara, research professor at the National Institute of Fundamental Studies, emphasised: “The hill country is a unique ecosystem and its restoration, too, has to be done with extreme care. Plants can help restore damaged ecosystems, but the species must be carefully selected.”
Conservationists call for science-led biodiversity assessments and climate-resilient planning. They urge reclamation of critical hotspots for nature and monitored restoration using native species.
The Cyclone Ditwah Central Highlands event highlights vulnerabilities across South Asia, where extreme weather increasingly threatens fragile mountain ecosystems and endemic biodiversity. Coordinated, evidence-based recovery will determine the long-term resilience of these vital regions.
Background
Sri Lanka faces frequent extreme weather. A pattern intensified by climate change. Past events exposed similar risks in highlands, but comprehensive post-disaster ecological mechanisms remain absent.
What’s Next
Experts advocate immediate drone and field surveys once access improves. They push for legally enforced land use rules and international support for restoration. The crisis offers scope to shift tourism towards low-impact trekking in sensitive habitats.
Published in SouthAsianDesk, December 16th, 2025
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