CHENNAI: A study conducted by researchers from Anna University indicates that climate change could trigger an alarming shift in the Western Ghats' ecosystem in Tamil Nadu by 2050, with more than 720 sq km of evergreen and deciduous forests projected to disappear and be replaced by thorn vegetation.
The study, carried out by the Centre for Climate Change and Disaster Management (CCCDM) at Anna University and published in the journal Scientific Reports, warns that rising temperatures, erratic rainfall patterns and increasing climate variability are projected to alter the ecological character of large stretches of the Western Ghats, one of the world's most important biodiversity hotspots.
Using advanced ecological niche modelling and climate projections under the SSP2-4.5 greenhouse gas emission scenario, researchers assessed the future distribution of major forest types across the Tamil Nadu portion of the mountain range between 2021 and 2050. The findings indicate that tropical evergreen forests could lose around 248.72 sq km of suitable habitat, while deciduous forests may shrink by 720.21 sq km. In contrast, xerophytic thorn forests are expected to expand by nearly 968.93 sq km.
The study was undertaken by scientists Andimuthu Ramachandran, Mithilasri Manickavasagam and Kurian Joseph, who conducted extensive field surveys across 929 reserve forests located in the Tamil Nadu segment of the Western Ghats. The survey covered elevations ranging from 180 metres to 2,637 metres above mean sea level.
According to the researchers, rising annual temperatures and increasing rainfall variability are disrupting the environmental conditions these species require to survive in their traditional habitats. Changing climatic conditions are expected to drive shifts in forest ecosystems, with vegetation migrating, contracting, or expanding into new areas.
Coimbatore district is projected to lose more than 50 sq km of evergreen forest habitat and about 24 sq km of deciduous forest area. At the same time, thorn vegetation could increase by more than 74 sq km. The study identifies the ecologically important Anaimalai landscape as one of the regions vulnerable to a major shift in vegetation composition.
Erode district is expected to witness one of the largest transformations, with nearly 183 sq km of deciduous forests becoming unsuitable in future and much of this area could be replaced by thorn vegetation, resulting in a net increase of around 184 sq km of dry forest cover.
Similar trends were observed in Dindigul, Dharmapuri, Tiruppur and Tirunelveli districts. In Dindigul, evergreen and deciduous forests are projected to decline significantly, while thorn vegetation could expand by nearly 88 sq km. Tirunelveli may lose more than 120 sq km of wetter forest ecosystems. Even the Nilgiris, known for its high altitude forests and biodiversity, could experience a decline in the evergreen forest ecosystem.
The Western Ghats, recognised as a UNESCO World Heritage Site and home to numerous endemic species found nowhere else in the world, play a crucial role in regulating climate and water resources across southern India. The mountain chain intercepts monsoon winds and serves as the catchment area for several major rivers, including the Bhavani, Vaigai and Thamirabarani.
Highlighting that the expansion of thorn forests indicates ecosystem degradation, researchers noted that the implications extend far beyond changes in vegetation cover. Compared to evergreen forests, thorn ecosystems support fewer specialised plant and animal species.
Speaking to DT Next, activist Osai Kalidasan said that environmental changes have significantly affected the ecological system. As evidence of this shift, he pointed out that elephants were recently spotted at Doddabetta Peak, a phenomenon that had never been recorded before. He also noted that peacocks were traditionally not found above 1,000 metres, but are now being observed at elevations exceeding 2,000 metres, indicating that ecological changes are occurring before our eyes.
Pointing out that evergreen forests are the primary source of many South Indian rivers, Kalidasan said any degradation of these forests would have a direct impact on water resources and the livelihoods of people across the southern states. He urged both the state and union governments to implement the Madhav Gadgil Report.
Officially submitted by the Western Ghats Ecology Expert Panel (WGEEP) in 2011, the report is a landmark environmental study that recommends measures for the conservation and sustainable management of the Western Ghats. Kalidasan stressed that the report's recommendations should be implemented to protect the fragile ecosystem of the Western Ghats.