Climate change destabilising Western Ghats’ forest ecosystems in Nilgiri Biosphere Reserve, warn researchers
Researchers have flagged that climate change is destabilising forest ecosystems within the Nilgiri Biosphere Reserve (NBR) in the Western Ghats.
Warming temperatures combined with more erratic rainfall (a rise in extreme rainfall events alongside a decline in moderate rainfall events) are disrupting the ecological balance of the reserve's montane forest-grassland mosaic.
The changes are altering the equilibrium between shola forest patches and adjoining grasslands, with implications for endemic species dependent on this specialised habitat.
The findings add to a growing body of long-term monitoring research (including forest phenology studies spanning two decades) tracking how the Western Ghats' biodiversity hotspot is responding to a changing climate.
Biosphere Reserve — UNESCO Man and Biosphere (MAB) Programme
A Biosphere Reserve is an internationally recognised land/coastal area, designated under UNESCO's Man and Biosphere (MAB) Programme (launched 1971), that reconciles biodiversity conservation with sustainable use. It follows a three-zone structure: a strictly protected core zone, a buffer zone permitting regulated activity (research, education, tourism), and a transition zone where local communities practise sustainable resource use. This distinguishes it from a National Park (no human activity permitted) or Wildlife Sanctuary (limited, regulated human activity permitted), which are legal categories under the Wildlife Protection Act, 1972, whereas a Biosphere Reserve is a broader UNESCO/administrative designation that can encompass multiple protected areas plus inhabited land.
Key Details
- MAB Programme launched by UNESCO in 1971; India notifies Biosphere Reserves domestically, and they are separately nominated for inclusion in UNESCO's World Network of Biosphere Reserves (WNBR).
- Core-buffer-transition zonation is the defining structural feature distinguishing Biosphere Reserves from National Parks/Wildlife Sanctuaries.
- India currently has 18 Biosphere Reserves notified; a subset of these are internationally recognised under the WNBR.
The Nilgiri Biosphere Reserve is the specific site where the climate-driven ecological disruption was observed, making the Biosphere Reserve framework (and its multi-use zonation) directly relevant to understanding why both conservation and community land use are affected.
Nilgiri Biosphere Reserve (NBR) — India's First Biosphere Reserve
The NBR was constituted by the Government of India in September 1986, making it India's first Biosphere Reserve, and was subsequently included in UNESCO's World Network of Biosphere Reserves in 2000. It spans roughly 5,520 sq km across the tri-junction of Tamil Nadu, Karnataka, and Kerala in the Western Ghats' Nilgiri Hills, encompassing protected areas such as Mudumalai, Bandipur, Nagarhole, Wayanad, and Silent Valley.
Key Details
- Established: September 1986 (first Biosphere Reserve in India); added to UNESCO's World Network of Biosphere Reserves in 2000.
- Spans three states: Tamil Nadu, Karnataka, and Kerala.
- Notable endemic and threatened fauna: Nilgiri Tahr (state animal of Tamil Nadu; endangered, endemic to the Western Ghats' high-elevation grasslands) and the Lion-Tailed Macaque (endangered, endemic to the Western Ghats' rainforest canopy).
As India's oldest and one of its most ecologically significant Biosphere Reserves, the NBR is a key long-term monitoring site — making it a natural focus for research tracking climate change impacts on Western Ghats ecosystems over multi-decade timescales.
Shola Forest-Grassland Mosaic — A Unique Montane Ecosystem
Sholas are compact, closed-canopy, stunted evergreen forest patches confined to sheltered folds of hills above roughly 1,800 metres in the Western Ghats and adjoining Nilgiri, Anamalai, and Palani hill ranges, interspersed with rolling montane grasslands. This forest-grassland mosaic is unlike typical tropical forest formations elsewhere in India and plays an outsized role in regulating the hydrology of lowland rivers originating in the Western Ghats.
Key Details
- Confined to elevations above approximately 1,800 m; found only in the southern Western Ghats' high hill ranges (Nilgiris, Anamalais, Palanis).
- Climate change is projected to shift the equilibrium between forest and grassland components of this mosaic, with warming and altered rainfall favouring forest encroachment into grasslands in some models, while invasive plantations (e.g., eucalyptus, wattle) independently reduce grassland extent.
- Grasslands within this mosaic support the endangered, endemic Nilgiri Tahr; degradation of shola-grassland habitat is a direct threat to this species' survival.
The reported destabilisation directly concerns this shola-grassland equilibrium — the specific ecological structure the Nilgiri Biosphere Reserve was designated to protect.
Western Ghats — UNESCO World Heritage Site and Biodiversity Hotspot
The Western Ghats were inscribed as a UNESCO World Heritage Site in 2012 as a serial site of 39 component parts (national parks, wildlife sanctuaries, and reserve forests) spread across Kerala, Tamil Nadu, Karnataka, and Maharashtra. It is recognised as one of the world's eight "hottest hotspots" of biological diversity, and its conservation-versus-development tension has been the subject of two major expert panels.
Key Details
- UNESCO World Heritage Site inscription: 2012; 39 serial component sites across four states.
- Western Ghats Ecology Expert Panel (Gadgil Committee, 2011) recommended declaring roughly 64% of the Western Ghats as Ecologically Sensitive Area (ESA) under a graded (zone-based) regime.
- The Kasturirangan Committee (High-Level Working Group, 2013) scaled this back, recommending ESA status for about 37% of the Western Ghats, focused on remaining natural/forested landscape rather than the entire region.
- The Nilgiri Biosphere Reserve lies within this larger Western Ghats landscape and overlaps with several of the 39 UNESCO-inscribed component sites.
The research on Nilgiri Biosphere Reserve destabilisation is a case study within the wider, UPSC-relevant debate on Western Ghats conservation, ESA delineation, and the trade-off between ecological protection and development pressure across this biodiversity hotspot.
- Nilgiri Biosphere Reserve established: September 1986 (first Biosphere Reserve in India); area approximately 5,520 sq km across Tamil Nadu, Karnataka, and Kerala.
- Included in UNESCO World Network of Biosphere Reserves: 2000.
- Western Ghats inscribed as UNESCO World Heritage Site: 2012, comprising 39 serial component sites across 4 states.
- Gadgil Committee (2011): recommended ~64% of Western Ghats as Ecologically Sensitive Area.
- Kasturirangan Committee (2013): recommended ~37% of Western Ghats as Ecologically Sensitive Area.
- Shola forests occur above approximately 1,800 m elevation, confined to the southern Western Ghats' high hill ranges.
- Key endemic/threatened species linked to the shola-grassland ecosystem: Nilgiri Tahr and Lion-Tailed Macaque (both endangered).